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• WPF Prism's delegatecommand not refreshing

  - by gkar

  I am building wpf edit form, that has two buttons, BeginEdit and Save And the form is bound to ViewModel that inherits from Prism's NotificationObject. There is a property called IsReadOnly And there are two commands that are Prism's DelegateCommands BeginEdit command and save command The code is here private DelegateCommand _beginEdit; public DelegateCommand BeginEdit { get { return _beginEdit ?? (_beginEdit = new DelegateCommand(() => this.IsReadOnly = false , () => IsReadOnly)); } } private bool _isReadOnly; public bool IsReadOnly { get { return _isReadOnly; } set { _isReadOnly = value; RaisePropertyChanged("IsReadOnly"); } } private DelegateCommand _saveEdit; public DelegateCommand SaveEdit { get { return _saveEdit ?? (_saveEdit = new DelegateCommand(() => this.IsReadOnly = true , () => !IsReadOnly)); } } So, as you see, the command will set IsReadOnly property to true or false, and CanExecute should get its value from the same property as well. It works when I start the form. But after I press BeginEdit, the buttons stays as the same, and the canExecute is not reflecting the new value of IsReadOnly

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• Memory leak in WPF app due to DelegateCommand.

  - by Abdullah BaMusa

  I just finished desktop apps written in WPF and c# using MVVM pattern. In this app I used Delegate Command implementation to wrap the ICommands properties exposed in my ModelView. The problem is these DelegateCommands prevent my ModelView and View from being garbage collected after closing the view. So it stays larking until I terminate the whole application. I profile the application I find it’s all about delegatecommand that keeping the modelview in memory. How could I avoid this situation and is this in nature of mvvm pattern, or it’s about my implantation of the pattern?. Thanks

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• How can you unit test a DelegateCommand

  - by Damian

  I am trying to unit test my ViewModel and my SaveItem(save, CanSave) delegate command. I want to ensure that CanSave is called and returns the correct value given certain conditions. Basically, how can I invoke the delegate command from my unit test, actually it's more of an integration test. Obviously I could just test the return value of the CanSave method but I am trying to use BDD to the letter, ie. no code without a test first.

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• Silverlight Commands Hacks: Passing EventArgs as CommandParameter to DelegateCommand triggered by Ev

  - by brainbox

  Today I've tried to find a way how to pass EventArgs as CommandParameter to DelegateCommand triggered by EventTrigger. By reverse engineering of default InvokeCommandAction I find that blend team just ignores event args.To resolve this issue I have created my own action for triggering delegate commands.public sealed class InvokeDelegateCommandAction : TriggerAction<DependencyObject>{    /// <summary>    ///     /// </summary>    public static readonly DependencyProperty CommandParameterProperty =        DependencyProperty.Register("CommandParameter", typeof(object), typeof(InvokeDelegateCommandAction), null);    /// <summary>    ///     /// </summary>    public static readonly DependencyProperty CommandProperty = DependencyProperty.Register(        "Command", typeof(ICommand), typeof(InvokeDelegateCommandAction), null);    /// <summary>    ///     /// </summary>    public static readonly DependencyProperty InvokeParameterProperty = DependencyProperty.Register(        "InvokeParameter", typeof(object), typeof(InvokeDelegateCommandAction), null);    private string commandName;    /// <summary>    ///     /// </summary>    public object InvokeParameter    {        get        {            return this.GetValue(InvokeParameterProperty);        }        set        {            this.SetValue(InvokeParameterProperty, value);        }    }    /// <summary>    ///     /// </summary>    public ICommand Command    {        get        {            return (ICommand)this.GetValue(CommandProperty);        }        set        {            this.SetValue(CommandProperty, value);        }    }    /// <summary>    ///     /// </summary>    public string CommandName    {        get        {            return this.commandName;        }        set        {            if (this.CommandName != value)            {                this.commandName = value;            }        }    }    /// <summary>    ///     /// </summary>    public object CommandParameter    {        get        {            return this.GetValue(CommandParameterProperty);        }        set        {            this.SetValue(CommandParameterProperty, value);        }    }    /// <summary>    ///     /// </summary>    /// <param name="parameter"></param>    protected override void Invoke(object parameter)    {        this.InvokeParameter = parameter;                if (this.AssociatedObject != null)        {            ICommand command = this.ResolveCommand();            if ((command != null) && command.CanExecute(this.CommandParameter))            {                command.Execute(this.CommandParameter);            }        }    }    private ICommand ResolveCommand()    {        ICommand command = null;        if (this.Command != null)        {            return this.Command;        }        var frameworkElement = this.AssociatedObject as FrameworkElement;        if (frameworkElement != null)        {            object dataContext = frameworkElement.DataContext;            if (dataContext != null)            {                PropertyInfo commandPropertyInfo = dataContext                    .GetType()                    .GetProperties(BindingFlags.Public | BindingFlags.Instance)                    .FirstOrDefault(                        p =>                        typeof(ICommand).IsAssignableFrom(p.PropertyType) &&                        string.Equals(p.Name, this.CommandName, StringComparison.Ordinal)                    );                if (commandPropertyInfo != null)                {                    command = (ICommand)commandPropertyInfo.GetValue(dataContext, null);                }            }        }        return command;    }}Example:<ComboBox>    <ComboBoxItem Content="Foo option 1" />    <ComboBoxItem Content="Foo option 2" />    <ComboBoxItem Content="Foo option 3" />    <Interactivity:Interaction.Triggers>        <Interactivity:EventTrigger EventName="SelectionChanged" >            <Presentation:InvokeDelegateCommandAction                 Command="{Binding SubmitFormCommand}"                CommandParameter="{Binding RelativeSource={RelativeSource Self}, Path=InvokeParameter}" />        </Interactivity:EventTrigger>    </Interactivity:Interaction.Triggers>                </ComboBox>BTW: InvokeCommanAction CommandName property are trying to find command in properties of view. It very strange, because in MVVM pattern command should be in viewmodel supplied to datacontext.

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• Silverlight Recruiting Application Part 5 - Jobs Module / View

  Now we starting getting into a more code-heavy portion of this series, thankfully though this means the groundwork is all set for the most part and after adding the modules we will have a complete application that can be provided with full source. The Jobs module will have two concerns- adding and maintaining jobs that can then be broadcast out to the website. How they are displayed on the site will be handled by our admin system (which will just poll from this common database), so we aren't too concerned with that, but rather with getting the information into the system and allowing the backend administration/HR users to keep things up to date. Since there is a fair bit of information that we want to display, we're going to move editing to a separate view so we can get all that information in an easy-to-use spot. With all the files created for this module, the project looks something like this: And now... on to the code. XAML for the Job Posting View All we really need for the Job Posting View is a RadGridView and a few buttons. This will let us both show off records and perform operations on the records without much hassle. That XAML is going to look something like this: 01.<Grid x:Name="LayoutRoot" 02.Background="White"> 03.<Grid.RowDefinitions> 04.<RowDefinition Height="30" /> 05.<RowDefinition /> 06.</Grid.RowDefinitions> 07.<StackPanel Orientation="Horizontal"> 08.<Button x:Name="xAddRecordButton" 09.Content="Add Job" 10.Width="120" 11.cal:Click.Command="{Binding AddRecord}" 12.telerik:StyleManager.Theme="Windows7" /> 13.<Button x:Name="xEditRecordButton" 14.Content="Edit Job" 15.Width="120" 16.cal:Click.Command="{Binding EditRecord}" 17.telerik:StyleManager.Theme="Windows7" /> 18.</StackPanel> 19.<telerikGrid:RadGridView x:Name="xJobsGrid" 20.Grid.Row="1" 21.IsReadOnly="True" 22.AutoGenerateColumns="False" 23.ColumnWidth="*" 24.RowDetailsVisibilityMode="VisibleWhenSelected" 25.ItemsSource="{Binding MyJobs}" 26.SelectedItem="{Binding SelectedJob, Mode=TwoWay}" 27.command:SelectedItemChangedEventClass.Command="{Binding SelectedItemChanged}"> 28.<telerikGrid:RadGridView.Columns> 29.<telerikGrid:GridViewDataColumn Header="Job Title" 30.DataMemberBinding="{Binding JobTitle}" 31.UniqueName="JobTitle" /> 32.<telerikGrid:GridViewDataColumn Header="Location" 33.DataMemberBinding="{Binding Location}" 34.UniqueName="Location" /> 35.<telerikGrid:GridViewDataColumn Header="Resume Required" 36.DataMemberBinding="{Binding NeedsResume}" 37.UniqueName="NeedsResume" /> 38.<telerikGrid:GridViewDataColumn Header="CV Required" 39.DataMemberBinding="{Binding NeedsCV}" 40.UniqueName="NeedsCV" /> 41.<telerikGrid:GridViewDataColumn Header="Overview Required" 42.DataMemberBinding="{Binding NeedsOverview}" 43.UniqueName="NeedsOverview" /> 44.<telerikGrid:GridViewDataColumn Header="Active" 45.DataMemberBinding="{Binding IsActive}" 46.UniqueName="IsActive" /> 47.</telerikGrid:RadGridView.Columns> 48.</telerikGrid:RadGridView> 49.</Grid> I'll explain what's happening here by line numbers: Lines 11 and 16: Using the same type of click commands as we saw in the Menu module, we tie the button clicks to delegate commands in the viewmodel. Line 25: The source for the jobs will be a collection in the viewmodel. Line 26: We also bind the selected item to a public property from the viewmodel for use in code. Line 27: We've turned the event into a command so we can handle it via code in the viewmodel. So those first three probably make sense to you as far as Silverlight/WPF binding magic is concerned, but for line 27... This actually comes from something I read onDamien Schenkelman's blog back in the day for creating an attached behavior from any event. So, any time you see me using command:Whatever.Command, the backing for it is actually something like this: SelectedItemChangedEventBehavior.cs: 01.public class SelectedItemChangedEventBehavior : CommandBehaviorBase<Telerik.Windows.Controls.DataControl> 02.{ 03.public SelectedItemChangedEventBehavior(DataControl element) 04.: base(element) 05.{ 06.element.SelectionChanged += new EventHandler<SelectionChangeEventArgs>(element_SelectionChanged); 07.} 08.void element_SelectionChanged(object sender, SelectionChangeEventArgs e) 09.{ 10.// We'll only ever allow single selection, so will only need item index 0 11.base.CommandParameter = e.AddedItems[0]; 12.base.ExecuteCommand(); 13.} 14.} SelectedItemChangedEventClass.cs: 01.public class SelectedItemChangedEventClass 02.{ 03.#region The Command Stuff 04.public static ICommand GetCommand(DependencyObject obj) 05.{ 06.return (ICommand)obj.GetValue(CommandProperty); 07.} 08.public static void SetCommand(DependencyObject obj, ICommand value) 09.{ 10.obj.SetValue(CommandProperty, value); 11.} 12.public static readonly DependencyProperty CommandProperty = 13.DependencyProperty.RegisterAttached("Command", typeof(ICommand), 14.typeof(SelectedItemChangedEventClass), new PropertyMetadata(OnSetCommandCallback)); 15.public static void OnSetCommandCallback(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs e) 16.{ 17.DataControl element = dependencyObject as DataControl; 18.if (element != null) 19.{ 20.SelectedItemChangedEventBehavior behavior = GetOrCreateBehavior(element); 21.behavior.Command = e.NewValue as ICommand; 22.} 23.} 24.#endregion 25.public static SelectedItemChangedEventBehavior GetOrCreateBehavior(DataControl element) 26.{ 27.SelectedItemChangedEventBehavior behavior = element.GetValue(SelectedItemChangedEventBehaviorProperty) as SelectedItemChangedEventBehavior; 28.if (behavior == null) 29.{ 30.behavior = new SelectedItemChangedEventBehavior(element); 31.element.SetValue(SelectedItemChangedEventBehaviorProperty, behavior); 32.} 33.return behavior; 34.} 35.public static SelectedItemChangedEventBehavior GetSelectedItemChangedEventBehavior(DependencyObject obj) 36.{ 37.return (SelectedItemChangedEventBehavior)obj.GetValue(SelectedItemChangedEventBehaviorProperty); 38.} 39.public static void SetSelectedItemChangedEventBehavior(DependencyObject obj, SelectedItemChangedEventBehavior value) 40.{ 41.obj.SetValue(SelectedItemChangedEventBehaviorProperty, value); 42.} 43.public static readonly DependencyProperty SelectedItemChangedEventBehaviorProperty = 44.DependencyProperty.RegisterAttached("SelectedItemChangedEventBehavior", 45.typeof(SelectedItemChangedEventBehavior), typeof(SelectedItemChangedEventClass), null); 46.} These end up looking very similar from command to command, but in a nutshell you create a command based on any event, determine what the parameter for it will be, then execute. It attaches via XAML and ties to a DelegateCommand in the viewmodel, so you get the full event experience (since some controls get a bit event-rich for added functionality). Simple enough, right? Viewmodel for the Job Posting View The Viewmodel is going to need to handle all events going back and forth, maintaining interactions with the data we are using, and both publishing and subscribing to events. Rather than breaking this into tons of little pieces, I'll give you a nice view of the entire viewmodel and then hit up the important points line-by-line: 001.public class JobPostingViewModel : ViewModelBase 002.{ 003.private readonly IEventAggregator eventAggregator; 004.private readonly IRegionManager regionManager; 005.public DelegateCommand<object> AddRecord { get; set; } 006.public DelegateCommand<object> EditRecord { get; set; } 007.public DelegateCommand<object> SelectedItemChanged { get; set; } 008.public RecruitingContext context; 009.private QueryableCollectionView _myJobs; 010.public QueryableCollectionView MyJobs 011.{ 012.get { return _myJobs; } 013.} 014.private QueryableCollectionView _selectionJobActionHistory; 015.public QueryableCollectionView SelectedJobActionHistory 016.{ 017.get { return _selectionJobActionHistory; } 018.} 019.private JobPosting _selectedJob; 020.public JobPosting SelectedJob 021.{ 022.get { return _selectedJob; } 023.set 024.{ 025.if (value != _selectedJob) 026.{ 027._selectedJob = value; 028.NotifyChanged("SelectedJob"); 029.} 030.} 031.} 032.public SubscriptionToken editToken = new SubscriptionToken(); 033.public SubscriptionToken addToken = new SubscriptionToken(); 034.public JobPostingViewModel(IEventAggregator eventAgg, IRegionManager regionmanager) 035.{ 036.// set Unity items 037.this.eventAggregator = eventAgg; 038.this.regionManager = regionmanager; 039.// load our context 040.context = new RecruitingContext(); 041.this._myJobs = new QueryableCollectionView(context.JobPostings); 042.context.Load(context.GetJobPostingsQuery()); 043.// set command events 044.this.AddRecord = new DelegateCommand<object>(this.AddNewRecord); 045.this.EditRecord = new DelegateCommand<object>(this.EditExistingRecord); 046.this.SelectedItemChanged = new DelegateCommand<object>(this.SelectedRecordChanged); 047.SetSubscriptions(); 048.} 049.#region DelegateCommands from View 050.public void AddNewRecord(object obj) 051.{ 052.this.eventAggregator.GetEvent<AddJobEvent>().Publish(true); 053.} 054.public void EditExistingRecord(object obj) 055.{ 056.if (_selectedJob == null) 057.{ 058.this.eventAggregator.GetEvent<NotifyUserEvent>().Publish("No job selected."); 059.} 060.else 061.{ 062.this._myJobs.EditItem(this._selectedJob); 063.this.eventAggregator.GetEvent<EditJobEvent>().Publish(this._selectedJob); 064.} 065.} 066.public void SelectedRecordChanged(object obj) 067.{ 068.if (obj.GetType() == typeof(ActionHistory)) 069.{ 070.// event bubbles up so we don't catch items from the ActionHistory grid 071.} 072.else 073.{ 074.JobPosting job = obj as JobPosting; 075.GrabHistory(job.PostingID); 076.} 077.} 078.#endregion 079.#region Subscription Declaration and Events 080.public void SetSubscriptions() 081.{ 082.EditJobCompleteEvent editComplete = eventAggregator.GetEvent<EditJobCompleteEvent>(); 083.if (editToken != null) 084.editComplete.Unsubscribe(editToken); 085.editToken = editComplete.Subscribe(this.EditCompleteEventHandler); 086.AddJobCompleteEvent addComplete = eventAggregator.GetEvent<AddJobCompleteEvent>(); 087.if (addToken != null) 088.addComplete.Unsubscribe(addToken); 089.addToken = addComplete.Subscribe(this.AddCompleteEventHandler); 090.} 091.public void EditCompleteEventHandler(bool complete) 092.{ 093.if (complete) 094.{ 095.JobPosting thisJob = _myJobs.CurrentEditItem as JobPosting; 096.this._myJobs.CommitEdit(); 097.this.context.SubmitChanges((s) => 098.{ 099.ActionHistory myAction = new ActionHistory(); 100.myAction.PostingID = thisJob.PostingID; 101.myAction.Description = String.Format("Job '{0}' has been edited by {1}", thisJob.JobTitle, "default user"); 102.myAction.TimeStamp = DateTime.Now; 103.eventAggregator.GetEvent<AddActionEvent>().Publish(myAction); 104.} 105., null); 106.} 107.else 108.{ 109.this._myJobs.CancelEdit(); 110.} 111.this.MakeMeActive(this.regionManager, "MainRegion", "JobPostingsView"); 112.} 113.public void AddCompleteEventHandler(JobPosting job) 114.{ 115.if (job == null) 116.{ 117.// do nothing, new job add cancelled 118.} 119.else 120.{ 121.this.context.JobPostings.Add(job); 122.this.context.SubmitChanges((s) => 123.{ 124.ActionHistory myAction = new ActionHistory(); 125.myAction.PostingID = job.PostingID; 126.myAction.Description = String.Format("Job '{0}' has been added by {1}", job.JobTitle, "default user"); 127.myAction.TimeStamp = DateTime.Now; 128.eventAggregator.GetEvent<AddActionEvent>().Publish(myAction); 129.} 130., null); 131.} 132.this.MakeMeActive(this.regionManager, "MainRegion", "JobPostingsView"); 133.} 134.#endregion 135.public void GrabHistory(int postID) 136.{ 137.context.ActionHistories.Clear(); 138._selectionJobActionHistory = new QueryableCollectionView(context.ActionHistories); 139.context.Load(context.GetHistoryForJobQuery(postID)); 140.} Taking it from the top, we're injecting an Event Aggregator and Region Manager for use down the road and also have the public DelegateCommands (just like in the Menu module). We also grab a reference to our context, which we'll obviously need for data, then set up a few fields with public properties tied to them. We're also setting subscription tokens, which we have not yet seen but I will get into below. The AddNewRecord (50) and EditExistingRecord (54) methods should speak for themselves for functionality, the one thing of note is we're sending events off to the Event Aggregator which some module, somewhere will take care of. Since these aren't entirely relying on one another, the Jobs View doesn't care if anyone is listening, but it will publish AddJobEvent (52), NotifyUserEvent (58) and EditJobEvent (63)regardless. Don't mind the GrabHistory() method so much, that is just grabbing history items (visibly being created in the SubmitChanges callbacks), and adding them to the database. Every action will trigger a history event, so we'll know who modified what and when, just in case. ;) So where are we at? Well, if we click to Add a job, we publish an event, if we edit a job, we publish an event with the selected record (attained through the magic of binding). Where is this all going though? To the Viewmodel, of course! XAML for the AddEditJobView This is pretty straightforward except for one thing, noted below: 001.<Grid x:Name="LayoutRoot" 002.Background="White"> 003.<Grid x:Name="xEditGrid" 004.Margin="10" 005.validationHelper:ValidationScope.Errors="{Binding Errors}"> 006.<Grid.Background> 007.<LinearGradientBrush EndPoint="0.5,1" 008.StartPoint="0.5,0"> 009.<GradientStop Color="#FFC7C7C7" 010.Offset="0" /> 011.<GradientStop Color="#FFF6F3F3" 012.Offset="1" /> 013.</LinearGradientBrush> 014.</Grid.Background> 015.<Grid.RowDefinitions> 016.<RowDefinition Height="40" /> 017.<RowDefinition Height="40" /> 018.<RowDefinition Height="40" /> 019.<RowDefinition Height="100" /> 020.<RowDefinition Height="100" /> 021.<RowDefinition Height="100" /> 022.<RowDefinition Height="40" /> 023.<RowDefinition Height="40" /> 024.<RowDefinition Height="40" /> 025.</Grid.RowDefinitions> 026.<Grid.ColumnDefinitions> 027.<ColumnDefinition Width="150" /> 028.<ColumnDefinition Width="150" /> 029.<ColumnDefinition Width="300" /> 030.<ColumnDefinition Width="100" /> 031.</Grid.ColumnDefinitions> 032.<!-- Title --> 033.<TextBlock Margin="8" 034.Text="{Binding AddEditString}" 035.TextWrapping="Wrap" 036.Grid.Column="1" 037.Grid.ColumnSpan="2" 038.FontSize="16" /> 039.<!-- Data entry area--> 040. 041.<TextBlock Margin="8,0,0,0" 042.Style="{StaticResource LabelTxb}" 043.Grid.Row="1" 044.Text="Job Title" 045.VerticalAlignment="Center" /> 046.<TextBox x:Name="xJobTitleTB" 047.Margin="0,8" 048.Grid.Column="1" 049.Grid.Row="1" 050.Text="{Binding activeJob.JobTitle, Mode=TwoWay, NotifyOnValidationError=True, ValidatesOnExceptions=True}" 051.Grid.ColumnSpan="2" /> 052.<TextBlock Margin="8,0,0,0" 053.Grid.Row="2" 054.Text="Location" 055.d:LayoutOverrides="Height" 056.VerticalAlignment="Center" /> 057.<TextBox x:Name="xLocationTB" 058.Margin="0,8" 059.Grid.Column="1" 060.Grid.Row="2" 061.Text="{Binding activeJob.Location, Mode=TwoWay, NotifyOnValidationError=True, ValidatesOnExceptions=True}" 062.Grid.ColumnSpan="2" /> 063. 064.<TextBlock Margin="8,11,8,0" 065.Grid.Row="3" 066.Text="Description" 067.TextWrapping="Wrap" 068.VerticalAlignment="Top" /> 069. 070.<TextBox x:Name="xDescriptionTB" 071.Height="84" 072.TextWrapping="Wrap" 073.ScrollViewer.VerticalScrollBarVisibility="Auto" 074.Grid.Column="1" 075.Grid.Row="3" 076.Text="{Binding activeJob.Description, Mode=TwoWay, NotifyOnValidationError=True, ValidatesOnExceptions=True}" 077.Grid.ColumnSpan="2" /> 078.<TextBlock Margin="8,11,8,0" 079.Grid.Row="4" 080.Text="Requirements" 081.TextWrapping="Wrap" 082.VerticalAlignment="Top" /> 083. 084.<TextBox x:Name="xRequirementsTB" 085.Height="84" 086.TextWrapping="Wrap" 087.ScrollViewer.VerticalScrollBarVisibility="Auto" 088.Grid.Column="1" 089.Grid.Row="4" 090.Text="{Binding activeJob.Requirements, Mode=TwoWay, NotifyOnValidationError=True, ValidatesOnExceptions=True}" 091.Grid.ColumnSpan="2" /> 092.<TextBlock Margin="8,11,8,0" 093.Grid.Row="5" 094.Text="Qualifications" 095.TextWrapping="Wrap" 096.VerticalAlignment="Top" /> 097. 098.<TextBox x:Name="xQualificationsTB" 099.Height="84" 100.TextWrapping="Wrap" 101.ScrollViewer.VerticalScrollBarVisibility="Auto" 102.Grid.Column="1" 103.Grid.Row="5" 104.Text="{Binding activeJob.Qualifications, Mode=TwoWay, NotifyOnValidationError=True, ValidatesOnExceptions=True}" 105.Grid.ColumnSpan="2" /> 106.<!-- Requirements Checkboxes--> 107. 108.<CheckBox x:Name="xResumeRequiredCB" Margin="8,8,8,15" 109.Content="Resume Required" 110.Grid.Row="6" 111.Grid.ColumnSpan="2" 112.IsChecked="{Binding activeJob.NeedsResume, Mode=TwoWay, NotifyOnValidationError=True, ValidatesOnExceptions=True}"/> 113. 114.<CheckBox x:Name="xCoverletterRequiredCB" Margin="8,8,8,15" 115.Content="Cover Letter Required" 116.Grid.Column="2" 117.Grid.Row="6" 118.IsChecked="{Binding activeJob.NeedsCV, Mode=TwoWay, NotifyOnValidationError=True, ValidatesOnExceptions=True}"/> 119. 120.<CheckBox x:Name="xOverviewRequiredCB" Margin="8,8,8,15" 121.Content="Overview Required" 122.Grid.Row="7" 123.Grid.ColumnSpan="2" 124.IsChecked="{Binding activeJob.NeedsOverview, Mode=TwoWay, NotifyOnValidationError=True, ValidatesOnExceptions=True}"/> 125. 126.<CheckBox x:Name="xJobActiveCB" Margin="8,8,8,15" 127.Content="Job is Active" 128.Grid.Column="2" 129.Grid.Row="7" 130.IsChecked="{Binding activeJob.IsActive, Mode=TwoWay, NotifyOnValidationError=True, ValidatesOnExceptions=True}"/> 131. 132.<!-- Buttons --> 133. 134.<Button x:Name="xAddEditButton" Margin="8,8,0,10" 135.Content="{Binding AddEditButtonString}" 136.cal:Click.Command="{Binding AddEditCommand}" 137.Grid.Column="2" 138.Grid.Row="8" 139.HorizontalAlignment="Left" 140.Width="125" 141.telerik:StyleManager.Theme="Windows7" /> 142. 143.<Button x:Name="xCancelButton" HorizontalAlignment="Right" 144.Content="Cancel" 145.cal:Click.Command="{Binding CancelCommand}" 146.Margin="0,8,8,10" 147.Width="125" 148.Grid.Column="2" 149.Grid.Row="8" 150.telerik:StyleManager.Theme="Windows7" /> 151.</Grid> 152.</Grid> The 'validationHelper:ValidationScope' line may seem odd. This is a handy little trick for catching current and would-be validation errors when working in this whole setup. This all comes from an approach found on theJoy Of Code blog, although it looks like the story for this will be changing slightly with new advances in SL4/WCF RIA Services, so this section can definitely get an overhaul a little down the road. The code is the fun part of all this, so let us see what's happening under the hood. Viewmodel for the AddEditJobView We are going to see some of the same things happening here, so I'll skip over the repeat info and get right to the good stuff: 001.public class AddEditJobViewModel : ViewModelBase 002.{ 003.private readonly IEventAggregator eventAggregator; 004.private readonly IRegionManager regionManager; 005. 006.public RecruitingContext context; 007. 008.private JobPosting _activeJob; 009.public JobPosting activeJob 010.{ 011.get { return _activeJob; } 012.set 013.{ 014.if (_activeJob != value) 015.{ 016._activeJob = value; 017.NotifyChanged("activeJob"); 018.} 019.} 020.} 021. 022.public bool isNewJob; 023. 024.private string _addEditString; 025.public string AddEditString 026.{ 027.get { return _addEditString; } 028.set 029.{ 030.if (_addEditString != value) 031.{ 032._addEditString = value; 033.NotifyChanged("AddEditString"); 034.} 035.} 036.} 037. 038.private string _addEditButtonString; 039.public string AddEditButtonString 040.{ 041.get { return _addEditButtonString; } 042.set 043.{ 044.if (_addEditButtonString != value) 045.{ 046._addEditButtonString = value; 047.NotifyChanged("AddEditButtonString"); 048.} 049.} 050.} 051. 052.public SubscriptionToken addJobToken = new SubscriptionToken(); 053.public SubscriptionToken editJobToken = new SubscriptionToken(); 054. 055.public DelegateCommand<object> AddEditCommand { get; set; } 056.public DelegateCommand<object> CancelCommand { get; set; } 057. 058.private ObservableCollection<ValidationError> _errors = new ObservableCollection<ValidationError>(); 059.public ObservableCollection<ValidationError> Errors 060.{ 061.get { return _errors; } 062.} 063. 064.private ObservableCollection<ValidationResult> _valResults = new ObservableCollection<ValidationResult>(); 065.public ObservableCollection<ValidationResult> ValResults 066.{ 067.get { return this._valResults; } 068.} 069. 070.public AddEditJobViewModel(IEventAggregator eventAgg, IRegionManager regionmanager) 071.{ 072.// set Unity items 073.this.eventAggregator = eventAgg; 074.this.regionManager = regionmanager; 075. 076.context = new RecruitingContext(); 077. 078.AddEditCommand = new DelegateCommand<object>(this.AddEditJobCommand); 079.CancelCommand = new DelegateCommand<object>(this.CancelAddEditCommand); 080. 081.SetSubscriptions(); 082.} 083. 084.#region Subscription Declaration and Events 085. 086.public void SetSubscriptions() 087.{ 088.AddJobEvent addJob = this.eventAggregator.GetEvent<AddJobEvent>(); 089. 090.if (addJobToken != null) 091.addJob.Unsubscribe(addJobToken); 092. 093.addJobToken = addJob.Subscribe(this.AddJobEventHandler); 094. 095.EditJobEvent editJob = this.eventAggregator.GetEvent<EditJobEvent>(); 096. 097.if (editJobToken != null) 098.editJob.Unsubscribe(editJobToken); 099. 100.editJobToken = editJob.Subscribe(this.EditJobEventHandler); 101.} 102. 103.public void AddJobEventHandler(bool isNew) 104.{ 105.this.activeJob = null; 106.this.activeJob = new JobPosting(); 107.this.activeJob.IsActive = true; // We assume that we want a new job to go up immediately 108.this.isNewJob = true; 109.this.AddEditString = "Add New Job Posting"; 110.this.AddEditButtonString = "Add Job"; 111. 112.MakeMeActive(this.regionManager, "MainRegion", "AddEditJobView"); 113.} 114. 115.public void EditJobEventHandler(JobPosting editJob) 116.{ 117.this.activeJob = null; 118.this.activeJob = editJob; 119.this.isNewJob = false; 120.this.AddEditString = "Edit Job Posting"; 121.this.AddEditButtonString = "Edit Job"; 122. 123.MakeMeActive(this.regionManager, "MainRegion", "AddEditJobView"); 124.} 125. 126.#endregion 127. 128.#region DelegateCommands from View 129. 130.public void AddEditJobCommand(object obj) 131.{ 132.if (this.Errors.Count > 0) 133.{ 134.List<string> errorMessages = new List<string>(); 135. 136.foreach (var valR in this.Errors) 137.{ 138.errorMessages.Add(valR.Exception.Message); 139.} 140. 141.this.eventAggregator.GetEvent<DisplayValidationErrorsEvent>().Publish(errorMessages); 142. 143.} 144.else if (!Validator.TryValidateObject(this.activeJob, new ValidationContext(this.activeJob, null, null), _valResults, true)) 145.{ 146.List<string> errorMessages = new List<string>(); 147. 148.foreach (var valR in this._valResults) 149.{ 150.errorMessages.Add(valR.ErrorMessage); 151.} 152. 153.this._valResults.Clear(); 154. 155.this.eventAggregator.GetEvent<DisplayValidationErrorsEvent>().Publish(errorMessages); 156.} 157.else 158.{ 159.if (this.isNewJob) 160.{ 161.this.eventAggregator.GetEvent<AddJobCompleteEvent>().Publish(this.activeJob); 162.} 163.else 164.{ 165.this.eventAggregator.GetEvent<EditJobCompleteEvent>().Publish(true); 166.} 167.} 168.} 169. 170.public void CancelAddEditCommand(object obj) 171.{ 172.if (this.isNewJob) 173.{ 174.this.eventAggregator.GetEvent<AddJobCompleteEvent>().Publish(null); 175.} 176.else 177.{ 178.this.eventAggregator.GetEvent<EditJobCompleteEvent>().Publish(false); 179.} 180.} 181. 182.#endregion 183.} 184.} We start seeing something new on line 103- the AddJobEventHandler will create a new job and set that to the activeJob item on the ViewModel. When this is all set, the view calls that familiar MakeMeActive method to activate itself. I made a bit of a management call on making views self-activate like this, but I figured it works for one reason. As I create this application, views may not exist that I have in mind, so after a view receives its 'ping' from being subscribed to an event, it prepares whatever it needs to do and then goes active. This way if I don't have 'edit' hooked up, I can click as the day is long on the main view and won't get lost in an empty region. Total personal preference here. :) Everything else should again be pretty straightforward, although I do a bit of validation checking in the AddEditJobCommand, which can either fire off an event back to the main view/viewmodel if everything is a success or sent a list of errors to our notification module, which pops open a RadWindow with the alerts if any exist. As a bonus side note, here's what my WCF RIA Services metadata looks like for handling all of the validation: private JobPostingMetadata() { } [StringLength(2500, ErrorMessage = "Description should be more than one and less than 2500 characters.", MinimumLength = 1)] [Required(ErrorMessage = "Description is required.")] public string Description; [Required(ErrorMessage="Active Status is Required")] public bool IsActive; [StringLength(100, ErrorMessage = "Posting title must be more than 3 but less than 100 characters.", MinimumLength = 3)] [Required(ErrorMessage = "Job Title is required.")] public bool JobTitle; [Required] public string Location; public bool NeedsCV; public bool NeedsOverview; public bool NeedsResume; public int PostingID; [Required(ErrorMessage="Qualifications are required.")] [StringLength(2500, ErrorMessage="Qualifications should be more than one and less than 2500 characters.", MinimumLength=1)] public string Qualifications; [StringLength(2500, ErrorMessage = "Requirements should be more than one and less than 2500 characters.", MinimumLength = 1)] [Required(ErrorMessage="Requirements are required.")] public string Requirements;   The RecruitCB Alternative See all that Xaml I pasted above? Those are now two pieces sitting in the JobsView.xaml file now. The only real difference is that the xEditGrid now sits in the same place as xJobsGrid, with visibility swapping out between the two for a quick switch. I also took out all the cal: and command: command references and replaced Button events with clicks and the Grid selection command replaced with a SelectedItemChanged event. Also, at the bottom of the xEditGrid after the last button, I add a ValidationSummary (with Visibility=Collapsed) to catch any errors that are popping up. Simple as can be, and leads to this being the single code-behind file: 001.public partial class JobsView : UserControl 002.{ 003.public RecruitingContext context; 004.public JobPosting activeJob; 005.public bool isNew; 006.private ObservableCollection<ValidationResult> _valResults = new ObservableCollection<ValidationResult>(); 007.public ObservableCollection<ValidationResult> ValResults 008.{ 009.get { return this._valResults; } 010.} 011.public JobsView() 012.{ 013.InitializeComponent(); 014.this.Loaded += new RoutedEventHandler(JobsView_Loaded); 015.} 016.void JobsView_Loaded(object sender, RoutedEventArgs e) 017.{ 018.context = new RecruitingContext(); 019.xJobsGrid.ItemsSource = context.JobPostings; 020.context.Load(context.GetJobPostingsQuery()); 021.} 022.private void xAddRecordButton_Click(object sender, RoutedEventArgs e) 023.{ 024.activeJob = new JobPosting(); 025.isNew = true; 026.xAddEditTitle.Text = "Add a Job Posting"; 027.xAddEditButton.Content = "Add"; 028.xEditGrid.DataContext = activeJob; 029.HideJobsGrid(); 030.} 031.private void xEditRecordButton_Click(object sender, RoutedEventArgs e) 032.{ 033.activeJob = xJobsGrid.SelectedItem as JobPosting; 034.isNew = false; 035.xAddEditTitle.Text = "Edit a Job Posting"; 036.xAddEditButton.Content = "Edit"; 037.xEditGrid.DataContext = activeJob; 038.HideJobsGrid(); 039.} 040.private void xAddEditButton_Click(object sender, RoutedEventArgs e) 041.{ 042.if (!Validator.TryValidateObject(this.activeJob, new ValidationContext(this.activeJob, null, null), _valResults, true)) 043.{ 044.List<string> errorMessages = new List<string>(); 045.foreach (var valR in this._valResults) 046.{ 047.errorMessages.Add(valR.ErrorMessage); 048.} 049.this._valResults.Clear(); 050.ShowErrors(errorMessages); 051.} 052.else if (xSummary.Errors.Count > 0) 053.{ 054.List<string> errorMessages = new List<string>(); 055.foreach (var err in xSummary.Errors) 056.{ 057.errorMessages.Add(err.Message); 058.} 059.ShowErrors(errorMessages); 060.} 061.else 062.{ 063.if (this.isNew) 064.{ 065.context.JobPostings.Add(activeJob); 066.context.SubmitChanges((s) => 067.{ 068.ActionHistory thisAction = new ActionHistory(); 069.thisAction.PostingID = activeJob.PostingID; 070.thisAction.Description = String.Format("Job '{0}' has been edited by {1}", activeJob.JobTitle, "default user"); 071.thisAction.TimeStamp = DateTime.Now; 072.context.ActionHistories.Add(thisAction); 073.context.SubmitChanges(); 074.}, null); 075.} 076.else 077.{ 078.context.SubmitChanges((s) => 079.{ 080.ActionHistory thisAction = new ActionHistory(); 081.thisAction.PostingID = activeJob.PostingID; 082.thisAction.Description = String.Format("Job '{0}' has been added by {1}", activeJob.JobTitle, "default user"); 083.thisAction.TimeStamp = DateTime.Now; 084.context.ActionHistories.Add(thisAction); 085.context.SubmitChanges(); 086.}, null); 087.} 088.ShowJobsGrid(); 089.} 090.} 091.private void xCancelButton_Click(object sender, RoutedEventArgs e) 092.{ 093.ShowJobsGrid(); 094.} 095.private void ShowJobsGrid() 096.{ 097.xAddEditRecordButtonPanel.Visibility = Visibility.Visible; 098.xEditGrid.Visibility = Visibility.Collapsed; 099.xJobsGrid.Visibility = Visibility.Visible; 100.} 101.private void HideJobsGrid() 102.{ 103.xAddEditRecordButtonPanel.Visibility = Visibility.Collapsed; 104.xJobsGrid.Visibility = Visibility.Collapsed; 105.xEditGrid.Visibility = Visibility.Visible; 106.} 107.private void ShowErrors(List<string> errorList) 108.{ 109.string nm = "Errors received: \n"; 110.foreach (string anerror in errorList) 111.nm += anerror + "\n"; 112.RadWindow.Alert(nm); 113.} 114.} The first 39 lines should be pretty familiar, not doing anything too unorthodox to get this up and running. Once we hit the xAddEditButton_Click on line 40, we're still doing pretty much the same things except instead of checking the ValidationHelper errors, we both run a check on the current activeJob object as well as check the ValidationSummary errors list. Once that is set, we again use the callback of context.SubmitChanges (lines 68 and 78) to create an ActionHistory which we will use to track these items down the line. That's all? Essentially... yes. If you look back through this post, most of the code and adventures we have taken were just to get things working in the MVVM/Prism setup. Since I have the whole 'module' self-contained in a single JobView+code-behind setup, I don't have to worry about things like sending events off into space for someone to pick up, communicating through an Infrastructure project, or even re-inventing events to be used with attached behaviors. Everything just kinda works, and again with much less code. Here's a picture of the MVVM and Code-behind versions on the Jobs and AddEdit views, but since the functionality is the same in both apps you still cannot tell them apart (for two-strike): Looking ahead, the Applicants module is effectively the same thing as the Jobs module, so most of the code is being cut-and-pasted back and forth with minor tweaks here and there. So that one is being taken care of by me behind the scenes. Next time, we get into a new world of fun- the interview scheduling module, which will pull from available jobs and applicants for each interview being scheduled, tying everything together with RadScheduler to the rescue. Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• I know I'm doing something wrong with RaiseCanExecuteChanged and CanExecute

  - by Cowman

  Well after fiddling with MVVM light to get my button to enable and disable when I want it to... I sort of mashed things together until it worked. However, I just know I'm doing something wrong here. I have RaiseCanExecuteChanged and CanExecute in the same area being called. Surely this is not how it's done? Here's my xaml <Button Margin="10, 25, 10, 25" VerticalAlignment="Center" HorizontalAlignment="Center" Width="50" Height="50" Grid.Column="1" Grid.Row="3" Content="Host"> <i:Interaction.Triggers> <i:EventTrigger EventName="Click"> <mvvmLight:EventToCommand Command="{Binding HostChat}" MustToggleIsEnabled="True" /> </i:EventTrigger> </i:Interaction.Triggers> </Button> And here's my code public override void InitializeViewAndViewModel() { view = UnityContainer.Resolve<LoginPromptView>(); viewModel = UnityContainer.Resolve<LoginPromptViewModel>(); view.DataContext = viewModel; InjectViewIntoRegion(RegionNames.PopUpRegion, view, true); viewModel.HostChat = new DelegateCommand(ExecuteHostChat, CanHostChat); viewModel.PropertyChanged += new System.ComponentModel.PropertyChangedEventHandler(ViewModelPropertyChanged); } void ViewModelPropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e) { if (e.PropertyName == "Name" || e.PropertyName == "Port" || e.PropertyName == "Address") { (viewModel.HostChat as DelegateCommand).RaiseCanExecuteChanged(); (viewModel.HostChat as DelegateCommand).CanExecute(); } } public void ExecuteHostChat() { } public bool CanHostChat() { if (String.IsNullOrEmpty(viewModel.Address) || String.IsNullOrEmpty(viewModel.Port) || String.IsNullOrEmpty(viewModel.Name)) { return false; } else return true; } See how these two are together? Surely that can't be right. I mean... it WORKS for me... but something seems wrong about it. Shouldn't RaiseCanExecuteChanged call CanExecute? It doesn't... and so if I don't have that CanExecute in there, my control never toggles its IsEnabled like I need it to. (viewModel.HostChat as DelegateCommand).RaiseCanExecuteChanged(); (viewModel.HostChat as DelegateCommand).CanExecute();

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• MVVM Light Toolkit - RelayCommands, DelegateCommands, and ObservableObjects

  - by DanM

  I just started experimenting with Laurent Bugnion's MVVM Light Toolkit. I think I'm going to really like it, but I have a couple questions. Before I get to them, I need to explain where I'm coming from. I currently use a combination of Josh Smith's MVVM Foundation and another project on Codeplex called MVVM Toolkit. I use ObservableObject and Messenger from MVVM Foundation and DelegateCommand and CommandReference from MVVM Toolkit. The only real overlap between MVVM Foundation and MVVM Tookit is that they both have an implementation for ICommand: MVVM Foundation has a RelayCommand and MVVM Tookit has a DelegateCommand. Of these two, DelegateCommand appears to be more sophisticated. It employs a CommandManagerHelper that uses weak references to avoid memory leaks. With that said, a couple questions: Why does MVVM Light Toolkit use RelayCommand rather than DelegateCommand? Is the use of weak references in an ICommand unnecessary or not recommended for some reason? Why is there no ObservableObject in MVVM Light? ObservableObject is basically just the part of ViewModelBase that implements INotifyPropertyChanged, but it's very convenient to have as a separate class because view-models are not the only objects that need to implement INotifyPropertyChanged. For example, let's say you have DataGrid that binds to a list of Person objects. If any of the properties in Person can change while the user is viewing the DataGrid, Person would need to implement INotifyPropertyChanged. (I realize that if Person is auto-generated using something like LinqToSql, it will probably already implement INotifyPropertyChanged, but there are cases where I need to make a view-specific version of entity model objects, say, because I need to include a command to support a button column in a DataGrid.) Thanks.

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• mvvm - prismv2 - INotifyPropertyChanged

  - by depictureboy

  Since this is so long and prolapsed and really doesnt ask a coherent question: 1: what is the proper way to implement subproperties of a primary object in a viewmodel? 2: Has anyone found a way to fix the delegatecommand.RaiseCanExecuteChanged issue? or do I need to fix it myself until MS does? For the rest of the story...continue on. In my viewmodel i have a doctor object property that is tied to my Model.Doctor, which is an EF POCO object. I have onPropertyChanged("Doctor") in the setter as such: Private Property Doctor() As Model.Doctor Get Return _objDoctor End Get Set(ByVal Value As Model.Doctor) _objDoctor = Value OnPropertyChanged("Doctor") End Set End Property The only time OnPropertyChanged fires if the WHOLE object changes. This wouldnt be a problem except that I need to know when the properties of doctor changes, so that I can enable other controls on my form(save button for example). I have tried to implement it in this way: Public Property FirstName() As String Get Return _objDoctor.FirstName End Get Set(ByVal Value As String) _objDoctor.FirstName = Value OnPropertyChanged("Doctor") End Set End Property this is taken from the XAMLPowerToys controls from Karl Shifflet, so i have to assume that its correct. But for the life of me I cant get it to work. I have included PRISM in here because I am using a unity container to instantiate my view and it IS a singleton. I am getting change notification to the viewmodel via eventaggregator that then populates Doctor with the new value. The reason I am doing all this is because of PRISM's DelegateCommand. So maybe that is my real issue. It appears that there is a bug in DelegateCommand that does not fire the RaiseCanExecuteChanged method on the commands that implement it and therefore needs to be fired manually. I have the code for that in my onPropertyChangedEventHandler. Of course this isnt implemented through the ICommand interface either so I have to break and make my properties DelegateCommand(of X) so that I have access to RaiseCanExecuteChanged of each command.

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• Silverlight Recruiting Application Part 4 - Navigation and Modules

  After our brief intermission (and the craziness of Q1 2010 release week), we're back on track here and today we get to dive into how we are going to navigate through our applications as well as how to set up our modules. That way, as I start adding the functionality- adding Jobs and Applicants, Interview Scheduling, and finally a handy Dashboard- you'll see how everything is communicating back and forth. This is all leading up to an eventual webinar, in which I'll dive into this process and give a honest look at the current story for MVVM vs. Code-Behind applications. (For a look at the future with SL4 and a little thing called MEF, check out what Ross is doing over at his blog!) Preamble... Before getting into really talking about this app, I've done a little bit of work ahead of time to create a ton of files that I'll need. Since the webinar is going to cover the Dashboard, it's not here, but otherwise this is a look at what the project layout looks like (and remember, this is both projects since they share the .Web): So as you can see, from an architecture perspective, the code-behind app is much smaller and more streamlined- aka a better fit for the one man shop that is me. Each module in the MVVM app has the same setup, which is the Module class and corresponding Views and ViewModels. Since the code-behind app doesn't need a go-between project like Infrastructure, each MVVM module is instead replaced by a single Silverlight UserControl which will contain all the logic for each respective bit of functionality. My Very First Module Navigation is going to be key to my application, so I figured the first thing I would setup is my MenuModule. First step here is creating a Silverlight Class Library named MenuModule, creatingthe View and ViewModel folders, and adding the MenuModule.cs class to handle module loading. The most important thing here is that my MenuModule inherits from IModule, which runs an Initialize on each module as it is created that, in my case, adds the views to the correct regions. Here's the MenuModule.cs code: public class MenuModule : IModule { private readonly IRegionManager regionManager; private readonly IUnityContainer container; public MenuModule(IUnityContainer container, IRegionManager regionmanager) { this.container = container; this.regionManager = regionmanager; } public void Initialize() { var addMenuView = container.Resolve<MenuView>(); regionManager.Regions["MenuRegion"].Add(addMenuView); } } Pretty straightforward here... We inject a container and region manager from Prism/Unity, then upon initialization we grab the view (out of our Views folder) and add it to the region it needs to live in. Simple, right? When the MenuView is created, the only thing in the code-behind is a reference to the set the MenuViewModel as the DataContext. I'd like to achieve MVVM nirvana and have zero code-behind by placing the viewmodel in the XAML, but for the reasons listed further below I can't. Navigation - MVVM Since navigation isn't the biggest concern in putting this whole thing together, I'm using the Button control to handle different options for loading up views/modules. There is another reason for this- out of the box, Prism has command support for buttons, which is one less custom command I had to work up for the functionality I would need. This comes from the Microsoft.Practices.Composite.Presentation assembly and looks as follows when put in code: <Button x:Name="xGoToJobs" Style="{StaticResource menuStyle}" Content="Jobs" cal:Click.Command="{Binding GoModule}" cal:Click.CommandParameter="JobPostingsView" /> For quick reference, 'menuStyle' is just taking care of margins and spacing, otherwise it looks, feels, and functions like everyone's favorite Button. What MVVM's this up is that the Click.Command is tying to a DelegateCommand (also coming fromPrism) on the backend. This setup allows you to tie user interaction to a command you setup in your viewmodel, which replaces the standard event-based setup you'd see in the code-behind app. Due to databinding magic, it all just works. When we get looking at the DelegateCommand in code, it ends up like this: public class MenuViewModel : ViewModelBase { private readonly IRegionManager regionManager; public DelegateCommand<object> GoModule { get; set; } public MenuViewModel(IRegionManager regionmanager) { this.regionManager = regionmanager; this.GoModule = new DelegateCommand<object>(this.goToView); } public void goToView(object obj) { MakeMeActive(this.regionManager, "MainRegion", obj.ToString()); } } Another for reference, ViewModelBase takes care of iNotifyPropertyChanged and MakeMeActive, which switches views in the MainRegion based on the parameters. So our public DelegateCommand GoModule ties to our command on the view, that in turn calls goToView, and the parameter on the button is the name of the view (which we pass with obj.ToString()) to activate. And how do the views get the names I can pass as a string? When I called regionManager.Regions[regionname].Add(view), there is an overload that allows for .Add(view, "viewname"), with viewname being what I use to activate views. You'll see that in action next installment, just wanted to clarify how that works. With this setup, I create two more buttons in my MenuView and the MenuModule is good to go. Last step is to make sure my MenuModule loads in my Bootstrapper: protected override IModuleCatalog GetModuleCatalog() { ModuleCatalog catalog = new ModuleCatalog(); // add modules here catalog.AddModule(typeof(MenuModule.MenuModule)); return catalog; } Clean, simple, MVVM-delicious. Navigation - Code-Behind Keeping with the history of significantly shorter code-behind sections of this series, Navigation will be no different. I promise. As I explained in a prior post, due to the one-project setup I don't have to worry about the same concerns so my menu is part of MainPage.xaml. So I can cheese-it a bit, though, since I've already got three buttons all set I'm just copying that code and adding three click-events instead of the command/commandparameter setup: <!-- Menu Region --> <StackPanel Grid.Row="1" Orientation="Vertical"> <Button x:Name="xJobsButton" Content="Jobs" Style="{StaticResource menuStyleCB}" Click="xJobsButton_Click" /> <Button x:Name="xApplicantsButton" Content="Applicants" Style="{StaticResource menuStyleCB}" Click="xApplicantsButton_Click" /> <Button x:Name="xSchedulingModule" Content="Scheduling" Style="{StaticResource menuStyleCB}" Click="xSchedulingModule_Click" /> </StackPanel> Simple, easy to use events, and no extra assemblies required! Since the code for loading each view will be similar, we'll focus on JobsView for now.The code-behind with this setup looks something like... private JobsView _jobsView; public MainPage() { InitializeComponent(); } private void xJobsButton_Click(object sender, RoutedEventArgs e) { if (MainRegion.Content.GetType() != typeof(JobsView)) { if (_jobsView == null) _jobsView = new JobsView(); MainRegion.Content = _jobsView; } } What am I doing here? First, for each 'view' I create a private reference which MainPage will hold on to. This allows for a little bit of state-maintenance when switching views. When a button is clicked, first we make sure the 'view' typeisn't active (why load it again if it is already at center stage?), then we check if the view has been created and create if necessary, then load it up. Three steps to switching views and is easy as pie. Part 4 Results The end result of all this is that I now have a menu module (MVVM) and a menu section (code-behind) that load their respective views. Since I'm using the same exact XAML (except with commands/events depending on the project), the end result for both is again exactly the same and I'll show a slightly larger image to show it off: Next time, we add the Jobs Module and wire up RadGridView and a separate edit page to handle adding and editing new jobs. That's when things get fun. And somewhere down the line, I'll make the menu look slicker. :) Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Silverlight Recruiting Application Part 6 - Adding an Interview Scheduling Module/View

  Between the last post and this one I went ahead and carried the ideas for the Jobs module and view into the Applicants module and view- they're both doing more or less the same thing, except with different objects being at their core.  Made for an easy cut-and-paste operation with a few items being switched from one to another.  Now that we have the ability to add postings and applicants, wouldn't it be nice if we could schedule an interview?  Of course it would! Scheduling Module I think you get the drift from previous posts that these project structures start looking somewhat similar.  The interview scheduling module is no different than the rest- it gets a SchedulingModule.cs file at the root that inherits from IModule, and there is a single SchedulerView.xsml and SchedulerViewModel.cs setup for our V+VM.  We have one unique concern as we enter into this- RadScheduler deals with AppointmentsSource, not ItemsSource, so there are some special considerations to take into account when planning this module. First, I need something which inherits from AppointmentBase.  This is the core of the RadScheduler appointment, and if you are planning to do any form of custom appointment, you'll want it to inherit from this.  Then you can add-on functionality as needed.  Here is my addition to the mix, the InterviewAppointment: 01.public class InterviewAppointment : AppointmentBase 02.{ 03.    private int _applicantID; 04.    public int ApplicantID 05.    { 06.        get { return this._applicantID; } 07.        set 08.        { 09.            if (_applicantID != value) 10.            { 11.                _applicantID = value; 12.                OnPropertyChanged("ApplicantID"); 13.            } 14.        } 15.    } 16.   17.    private int _postingID; 18.    public int PostingID 19.    { 20.        get { return _postingID; } 21.        set 22.        { 23.            if (_postingID != value) 24.            { 25.                _postingID = value; 26.                OnPropertyChanged("PostingID"); 27.            } 28.        } 29.    } 30.   31.    private string _body; 32.    public string Body 33.    { 34.        get { return _body; } 35.        set 36.        { 37.            if (_body != value) 38.            { 39.                _body = value; 40.                OnPropertyChanged("Body"); 41.            } 42.        } 43.    } 44.   45.    private int _interviewID; 46.    public int InterviewID 47.    { 48.        get { return _interviewID; } 49.        set 50.        { 51.            if (_interviewID != value) 52.            { 53.                _interviewID = value; 54.                OnPropertyChanged("InterviewID"); 55.            } 56.        } 57.    } 58.   59.    public override IAppointment Copy() 60.    { 61.        IAppointment appointment = new InterviewAppointment(); 62.        appointment.CopyFrom(this);             63.        return appointment; 64.    } 65.   66.    public override void CopyFrom(IAppointment other) 67.    {             68.        base.CopyFrom(other); 69.        var appointment = other as InterviewAppointment; 70.        if (appointment != null) 71.        { 72.            ApplicantID = appointment.ApplicantID; 73.            PostingID = appointment.PostingID; 74.            Body = appointment.Body; 75.            InterviewID = appointment.InterviewID; 76.        } 77.    } 78.} Nothing too exciting going on here, we just make sure that our custom fields are persisted (specifically set in CopyFrom at the bottom) and notifications are fired- otherwise this ends up exactly like the standard appointment as far as interactions, etc.  But if we've got custom appointment items... that also means we need to customize what our appointment dialog window will look like. Customizing the Edit Appointment Dialog This initially sounds a lot more intimidating than it really is.  The first step here depends on what you're dealing with for theming, but for ease of everything I went ahead and extracted my templates in Blend for RadScheduler so I could modify it as I pleased.  For the faint of heart, the RadScheduler template is a few thousand lines of goodness since there are some very complex things going on in that control.  I've gone ahead and trimmed down the template parts I don't need as much as possible, so what is left is all that is relevant to the Edit Appointment Dialog.  Here's the resulting Xaml, with line numbers, so I can explain further: 001.<UserControl.Resources> 002.    <!-- begin Necessary Windows 7 Theme Resources for EditAppointmentTemplate --> 003.    <helpers:DataContextProxy x:Key="DataContextProxy" /> 004.       005.    <telerik:Windows7Theme x:Key="Theme" /> 006.    <SolidColorBrush x:Key="DialogWindowBackground" 007.                     Color="White" /> 008.    <SolidColorBrush x:Key="CategorySelectorBorderBrush" 009.                     Color="#FFB1B1B1" /> 010.    <LinearGradientBrush x:Key="RadToolBar_InnerBackground" 011.                         EndPoint="0.5,1" 012.                         StartPoint="0.5,0"> 013.        <GradientStop Color="#FFFDFEFF" 014.                      Offset="0" /> 015.        <GradientStop Color="#FFDDE9F7" 016.                      Offset="1" /> 017.        <GradientStop Color="#FFE6F0FA" 018.                      Offset="0.5" /> 019.        <GradientStop Color="#FFDCE6F4" 020.                      Offset="0.5" /> 021.    </LinearGradientBrush> 022.    <Style x:Key="FormElementTextBlockStyle" 023.           TargetType="TextBlock"> 024.        <Setter Property="HorizontalAlignment" 025.                Value="Right" /> 026.        <Setter Property="VerticalAlignment" 027.                Value="Top" /> 028.        <Setter Property="Margin" 029.                Value="15, 15, 0, 2" /> 030.    </Style> 031.    <Style x:Key="FormElementStyle" 032.           TargetType="FrameworkElement"> 033.        <Setter Property="Margin" 034.                Value="10, 10, 0, 2" /> 035.    </Style> 036.    <SolidColorBrush x:Key="GenericShallowBorderBrush" 037.                     Color="#FF979994" /> 038.    <telerik:BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter" /> 039.    <telerikScheduler:ImportanceToBooleanConverter x:Key="ImportanceToBooleanConverter" /> 040.    <telerikScheduler:NullToVisibilityConverter x:Key="NullToVisibilityConverter" /> 041.    <telerikScheduler:InvertedNullToVisibilityConverter x:Key="InvertedNullToVisibilityConverter" /> 042.    <scheduler:ResourcesSeparatorConverter x:Key="ResourcesSeparatorConverter" /> 043.    <DataTemplate x:Key="IconDataEditTemplate"> 044.        <Image Source="/Telerik.Windows.Controls.Scheduler;component/Themes/Office/Images/cal.png" 045.               Margin="3,3,0,0" 046.               Width="16" 047.               Height="16" /> 048.    </DataTemplate> 049.    <DataTemplate x:Key="SingleSelectionTemplate"> 050.        <Grid VerticalAlignment="Stretch" 051.              HorizontalAlignment="Stretch"> 052.            <Grid.RowDefinitions> 053.                <RowDefinition Height="Auto" /> 054.            </Grid.RowDefinitions> 055.            <Grid.ColumnDefinitions> 056.                <ColumnDefinition Width="Auto" 057.                                  MinWidth="84" /> 058.                <ColumnDefinition Width="Auto" 059.                                  MinWidth="200" /> 060.            </Grid.ColumnDefinitions> 061.            <TextBlock x:Name="SelectionNameLabel" 062.                       Margin="0,13,4,2" 063.                       Text="{Binding ResourceType.DisplayName}" 064.                       Style="{StaticResource FormElementTextBlockStyle}" 065.                       Grid.Column="0" /> 066.            <telerikInput:RadComboBox ItemsSource="{Binding ResourceItems}" 067.                                      Width="185" 068.                                      Margin="5,10,20,2" 069.                                      HorizontalAlignment="Left" 070.                                      Grid.Column="1" 071.                                      ClearSelectionButtonVisibility="Visible" 072.                                      ClearSelectionButtonContent="Clear All" 073.                                      DisplayMemberPath="Resource.DisplayName" 074.                                      telerik:StyleManager.Theme="{StaticResource Theme}" 075.                                      SelectedItem="{Binding SelectedItem, Mode=TwoWay}" /> 076.        </Grid> 077.    </DataTemplate> 078.    <DataTemplate x:Key="MultipleSelectionTemplate"> 079.        <Grid VerticalAlignment="Stretch" 080.              HorizontalAlignment="Stretch"> 081.            <Grid.RowDefinitions> 082.                <RowDefinition Height="Auto" /> 083.            </Grid.RowDefinitions> 084.            <Grid.ColumnDefinitions> 085.                <ColumnDefinition Width="Auto" 086.                                  MinWidth="84" /> 087.                <ColumnDefinition Width="Auto" 088.                                  MinWidth="200" /> 089.            </Grid.ColumnDefinitions> 090.            <TextBlock x:Name="SelectionNameLabel" 091.                       Grid.Column="0" 092.                       Text="{Binding ResourceType.DisplayName}" 093.                       Margin="0,13,4,2" 094.                       Style="{StaticResource FormElementTextBlockStyle}" /> 095.            <telerikInput:RadComboBox Grid.Column="1" 096.                                      Width="185" 097.                                      HorizontalAlignment="Left" 098.                                      Margin="5,10,20,2" 099.                                      ItemsSource="{Binding ResourceItems}" 100.                                      SelectedIndex="{Binding SelectedIndex, Mode=TwoWay}" 101.                                      ClearSelectionButtonVisibility="Visible" 102.                                      ClearSelectionButtonContent="Clear All" 103.                                      telerik:StyleManager.Theme="{StaticResource Theme}"> 104.                <telerikInput:RadComboBox.ItemTemplate> 105.                    <DataTemplate> 106.                        <Grid HorizontalAlignment="Stretch" 107.                              VerticalAlignment="Stretch"> 108.                            <CheckBox VerticalAlignment="Center" 109.                                      HorizontalContentAlignment="Stretch" 110.                                      VerticalContentAlignment="Center" 111.                                      IsChecked="{Binding IsChecked, Mode=TwoWay}" 112.                                      Content="{Binding Resource.DisplayName}"> 113.                                <CheckBox.ContentTemplate> 114.                                    <DataTemplate> 115.                                        <TextBlock HorizontalAlignment="Stretch" 116.                                                   VerticalAlignment="Stretch" 117.                                                   Text="{Binding Content, RelativeSource={RelativeSource TemplatedParent}}" /> 118.                                    </DataTemplate> 119.                                </CheckBox.ContentTemplate> 120.                            </CheckBox> 121.                        </Grid> 122.                    </DataTemplate> 123.                </telerikInput:RadComboBox.ItemTemplate> 124.            </telerikInput:RadComboBox> 125.        </Grid> 126.    </DataTemplate> 127.    <scheduler:ResourceTypeTemplateSelector x:Key="ItemTemplateSelector" 128.                                            MultipleSelectionTemplate="{StaticResource MultipleSelectionTemplate}" 129.                                            SingleSelectionTemplate="{StaticResource SingleSelectionTemplate}" /> 130.    <!-- end Necessary Windows 7 Theme Resources for EditAppointmentTemplate -->  131.       132.    <ControlTemplate x:Key="EditAppointmentTemplate" 133.                     TargetType="telerikScheduler:AppointmentDialogWindow"> 134.        <StackPanel Background="{TemplateBinding Background}" 135.                    UseLayoutRounding="True"> 136.            <StackPanel Grid.Row="0" 137.                        Orientation="Horizontal" 138.                        Background="{StaticResource RadToolBar_InnerBackground}" 139.                        Grid.ColumnSpan="2" 140.                        Height="0"> 141.                <!-- Recurrence buttons --> 142.                <Border Margin="1,1,0,0" 143.                        Background="#50000000" 144.                        HorizontalAlignment="Left" 145.                        VerticalAlignment="Center" 146.                        Width="2" 147.                        Height="16"> 148.                    <Border Margin="0,0,1,1" 149.                            Background="#80FFFFFF" 150.                            HorizontalAlignment="Left" 151.                            Width="1" /> 152.                </Border> 153.                <Border Margin="1,1,0,0" 154.                        Background="#50000000" 155.                        HorizontalAlignment="Left" 156.                        VerticalAlignment="Center" 157.                        Width="2" 158.                        Height="16"> 159.                    <Border Margin="0,0,1,1" 160.                            Background="#80FFFFFF" 161.                            HorizontalAlignment="Left" 162.                            Width="1" /> 163.                </Border> 164.                <TextBlock telerik:LocalizationManager.ResourceKey="ShowAs" 165.                           VerticalAlignment="Center" 166.                           Margin="5,0,0,0" /> 167.                <telerikInput:RadComboBox ItemsSource="{TemplateBinding TimeMarkers}" 168.                                          Width="100" 169.                                          Height="20" 170.                                          VerticalAlignment="Center" 171.                                          Margin="5,0,0,0" 172.                                          ClearSelectionButtonVisibility="Visible" 173.                                          ClearSelectionButtonContent="Clear" 174.                                          SelectedItem="{Binding TimeMarker,RelativeSource={RelativeSource TemplatedParent},Mode=TwoWay}" 175.                                          telerik:StyleManager.Theme="{StaticResource Theme}"> 176.                    <telerikInput:RadComboBox.ItemTemplate> 177.                        <DataTemplate> 178.                            <StackPanel Orientation="Horizontal"> 179.                                <Rectangle Fill="{Binding TimeMarkerBrush}" 180.                                           Margin="2" 181.                                           Width="12" 182.                                           Height="12" /> 183.                                <TextBlock Text="{Binding TimeMarkerName}" 184.                                           Margin="2" /> 185.                            </StackPanel> 186.                        </DataTemplate> 187.                    </telerikInput:RadComboBox.ItemTemplate> 188.                </telerikInput:RadComboBox> 189.                <telerik:RadToggleButton x:Name="High" 190.                                         BorderThickness="0" 191.                                         Background="{StaticResource RadToolBar_InnerBackground}" 192.                                         DataContext="{TemplateBinding EditedAppointment}" 193.                                         telerik:StyleManager.Theme="{StaticResource Theme}" 194.                                         IsChecked="{Binding Importance,Mode=TwoWay, Converter={StaticResource ImportanceToBooleanConverter},ConverterParameter=High}" 195.                                         Margin="2,2,0,2" 196.                                         Width="23" 197.                                         Height="23" 198.                                         HorizontalContentAlignment="Center" 199.                                         ToolTipService.ToolTip="High importance" 200.                                         CommandParameter="High" 201.                                         Command="telerikScheduler:RadSchedulerCommands.SetAppointmentImportance"> 202.                    <StackPanel HorizontalAlignment="Center"> 203.                        <Path Stretch="Fill" 204.                              Height="10" 205.                              HorizontalAlignment="Center" 206.                              VerticalAlignment="Top" 207.                              Width="5.451" 208.                              Data="M200.39647,58.840393 C200.39337,58.336426 201.14566,57.683922 202.56244,57.684292 C204.06589,57.684685 204.73764,58.357765 204.72783,58.992363 C205.04649,61.795574 203.04713,64.181099 202.47388,66.133446 C201.93753,64.154961 199.9471,61.560352 200.39647,58.840393 z"> 209.                            <Path.Fill> 210.                                <LinearGradientBrush EndPoint="1.059,0.375" 211.                                                     StartPoint="-0.457,0.519"> 212.                                    <GradientStop Color="#FFFF0606" 213.                                                  Offset="0.609" /> 214.                                    <GradientStop Color="#FFBF0303" 215.                                                  Offset="0.927" /> 216.                                </LinearGradientBrush> 217.                            </Path.Fill> 218.                        </Path> 219.                        <Ellipse Height="3" 220.                                 HorizontalAlignment="Center" 221.                                 Margin="0,-1,0,0" 222.                                 VerticalAlignment="Top" 223.                                 Width="3"> 224.                            <Ellipse.Fill> 225.                                <RadialGradientBrush> 226.                                    <GradientStop Color="#FFFF0606" 227.                                                  Offset="0" /> 228.                                    <GradientStop Color="#FFBF0303" 229.                                                  Offset="1" /> 230.                                </RadialGradientBrush> 231.                            </Ellipse.Fill> 232.                        </Ellipse> 233.                    </StackPanel> 234.                </telerik:RadToggleButton> 235.                <telerik:RadToggleButton x:Name="Low" 236.                                         HorizontalContentAlignment="Center" 237.                                         BorderThickness="0" 238.                                         Background="{StaticResource RadToolBar_InnerBackground}" 239.                                         DataContext="{TemplateBinding EditedAppointment}" 240.                                         IsChecked="{Binding Importance,Mode=TwoWay, Converter={StaticResource ImportanceToBooleanConverter},ConverterParameter=Low}" 241.                                         Margin="0,2,0,2" 242.                                         Width="23" 243.                                         Height="23" 244.                                         ToolTipService.ToolTip="Low importance" 245.                                         CommandParameter="Low" 246.                                         telerik:StyleManager.Theme="{StaticResource Theme}" 247.                                         Command="telerikScheduler:RadSchedulerCommands.SetAppointmentImportance"> 248.                    <Path Stretch="Fill" 249.                          Height="12" 250.                          HorizontalAlignment="Center" 251.                          VerticalAlignment="Top" 252.                          Width="9" 253.                          Data="M222.40353,60.139881 L226.65768,60.139843 L226.63687,67.240196 L229.15347,67.240196 L224.37816,71.394943 L219.65274,67.240196 L222.37572,67.219345 z" 254.                          Stroke="#FF0365A7"> 255.                        <Path.Fill> 256.                            <LinearGradientBrush EndPoint="1.059,0.375" 257.                                                 StartPoint="-0.457,0.519"> 258.                                <GradientStop Color="#FFBBE4FF" /> 259.                                <GradientStop Color="#FF024572" 260.                                              Offset="0.836" /> 261.                                <GradientStop Color="#FF43ADF4" 262.                                              Offset="0.466" /> 263.                            </LinearGradientBrush> 264.                        </Path.Fill> 265.                    </Path> 266.                </telerik:RadToggleButton> 267.            </StackPanel > 268.            <Border DataContext="{TemplateBinding EditedAppointment}" 269.                    Background="{Binding Category.CategoryBrush}" 270.                    Visibility="{Binding Category,Converter={StaticResource NullToVisibilityConverter}}" 271.                    CornerRadius="3" 272.                    Height="20" 273.                    Margin="5,10,5,0"> 274.                <TextBlock Text="{Binding Category.DisplayName}" 275.                           VerticalAlignment="Center" 276.                           Margin="5,0,0,0" /> 277.            </Border> 278.            <Grid VerticalAlignment="Stretch" 279.                  HorizontalAlignment="Stretch" 280.                  DataContext="{TemplateBinding EditedAppointment}" 281.                  Background="{TemplateBinding Background}"> 282.                <Grid.RowDefinitions> 283.                    <RowDefinition Height="Auto" /> 284.                    <RowDefinition Height="Auto" /> 285.                    <RowDefinition Height="Auto" /> 286.                    <RowDefinition Height="Auto" /> 287.                    <RowDefinition Height="Auto" /> 288.                    <RowDefinition Height="Auto" /> 289.                    <RowDefinition Height="Auto" /> 290.                    <RowDefinition Height="Auto" /> 291.                    <RowDefinition Height="Auto" /> 292.                    <RowDefinition Height="Auto" /> 293.                </Grid.RowDefinitions> 294.                <Grid.ColumnDefinitions> 295.                    <ColumnDefinition Width="Auto" 296.                                      MinWidth="100" /> 297.                    <ColumnDefinition Width="Auto" 298.                                      MinWidth="200" /> 299.                </Grid.ColumnDefinitions> 300.                <!-- Subject --> 301.                <TextBlock x:Name="SubjectLabel" 302.                           Grid.Row="0" 303.                           Grid.Column="0" 304.                           Margin="0,15,0,2" 305.                           telerik:LocalizationManager.ResourceKey="Subject" 306.                           Style="{StaticResource FormElementTextBlockStyle}" /> 307.                <TextBox x:Name="Subject" 308.                         Grid.Row="0" 309.                         Grid.Column="1" 310.                         MinHeight="22" 311.                         Padding="4 2" 312.                         Width="340" 313.                         HorizontalAlignment="Left" 314.                         Text="{Binding Subject, Mode=TwoWay}" 315.                         MaxLength="255" 316.                         telerik:StyleManager.Theme="{StaticResource Theme}" 317.                         Margin="10,12,20,2" /> 318.                <!-- Description --> 319.                <TextBlock x:Name="DescriptionLabel" 320.                           Grid.Row="1" 321.                           Grid.Column="0" 322.                           Margin="0,13,0,2" 323.                           telerik:LocalizationManager.ResourceKey="Body" 324.                           Style="{StaticResource FormElementTextBlockStyle}" /> 325.                <TextBox x:Name="Body" 326.                         VerticalAlignment="top" 327.                         Grid.Row="1" 328.                         Grid.Column="1" 329.                         Height="Auto" 330.                         MaxHeight="82" 331.                         Width="340" 332.                         HorizontalAlignment="Left" 333.                         MinHeight="22" 334.                         Padding="4 2" 335.                         TextWrapping="Wrap" 336.                         telerik:StyleManager.Theme="{StaticResource Theme}" 337.                         Text="{Binding Body, Mode=TwoWay}" 338.                         AcceptsReturn="true" 339.                         Margin="10,10,20,2" 340.                         HorizontalScrollBarVisibility="Auto" 341.                         VerticalScrollBarVisibility="Auto" /> 342.                <!-- Start/End date --> 343.                <TextBlock x:Name="StartDateLabel" 344.                           Grid.Row="2" 345.                           Grid.Column="0" 346.                           Margin="0,13,0,2" 347.                           telerik:LocalizationManager.ResourceKey="StartTime" 348.                           Style="{StaticResource FormElementTextBlockStyle}" /> 349.                <telerikScheduler:DateTimePicker x:Name="StartDateTime" 350.                                                 Height="22" 351.                                                 Grid.Row="2" 352.                                                 Grid.Column="1" 353.                                                 HorizontalAlignment="Left" 354.                                                 Margin="10,10,20,2" 355.                                                 Style="{StaticResource FormElementStyle}" 356.                                                 SelectedDateTime="{Binding Start, Mode=TwoWay}" 357.                                                 telerikScheduler:StartEndDatePicker.EndPicker="{Binding ElementName=EndDateTime}" 358.                                                 IsTabStop="False" 359.                                                 IsEnabled="False" /> 360.                <TextBlock x:Name="EndDateLabel" 361.                           Grid.Row="3" 362.                           Grid.Column="0" 363.                           Margin="0,13,0,2" 364.                           telerik:LocalizationManager.ResourceKey="EndTime" 365.                           Style="{StaticResource FormElementTextBlockStyle}" /> 366.                <telerikScheduler:DateTimePicker x:Name="EndDateTime" 367.                                                 Height="22" 368.                                                 Grid.Row="3" 369.                                                 Grid.Column="1" 370.                                                 HorizontalAlignment="Left" 371.                                                 Margin="10,10,20,2" 372.                                                 Style="{StaticResource FormElementStyle}" 373.                                                 IsTabStop="False" 374.                                                 IsEnabled="False" 375.                                                 SelectedDateTime="{Binding End, Mode=TwoWay}" /> 376.                <!-- Is-all-day selector --> 377.                <CheckBox x:Name="AllDayEventCheckbox" 378.                          IsChecked="{Binding IsAllDayEvent, Mode=TwoWay}" 379.                          Grid.Row="4" 380.                          Grid.Column="1" 381.                          Margin="10,10,20,2" 382.                          HorizontalAlignment="Left" 383.                          telerik:StyleManager.Theme="{StaticResource Theme}" 384.                          telerik:LocalizationManager.ResourceKey="AllDayEvent"> 385.                    <telerik:CommandManager.InputBindings> 386.                        <telerik:InputBindingCollection> 387.                            <telerik:MouseBinding Command="telerikScheduler:RadSchedulerCommands.ChangeTimePickersVisibility" 388.                                                  Gesture="LeftClick" /> 389.                        </telerik:InputBindingCollection> 390.                    </telerik:CommandManager.InputBindings> 391.                </CheckBox> 392.                <Grid Grid.Row="5" 393.                      Grid.ColumnSpan="2"> 394.                    <Grid.ColumnDefinitions> 395.                        <ColumnDefinition Width="Auto" 396.                                          MinWidth="100" /> 397.                        <ColumnDefinition Width="Auto" 398.                                          MinWidth="200" /> 399.                    </Grid.ColumnDefinitions> 400.                    <Grid.RowDefinitions> 401.                        <RowDefinition Height="Auto" /> 402.                        <RowDefinition Height="Auto" /> 403.                    </Grid.RowDefinitions> 404.                    <TextBlock Text="Applicant" 405.                               Margin="0,13,0,2" 406.                               Style="{StaticResource FormElementTextBlockStyle}" /> 407.                    <telerikInput:RadComboBox IsEditable="False" 408.                                              Grid.Column="1" 409.                                              Height="24" 410.                                              VerticalAlignment="Center" 411.                                              ItemsSource="{Binding Source={StaticResource DataContextProxy}, Path=DataSource.ApplicantList}" 412.                                              SelectedValue="{Binding ApplicantID, Mode=TwoWay}" 413.                                              SelectedValuePath="ApplicantID" 414.                                              DisplayMemberPath="FirstName" /> 415.                       416.                    <TextBlock Text="Job" 417.                               Margin="0,13,0,2" 418.                               Grid.Row="1" 419.                               Style="{StaticResource FormElementTextBlockStyle}" /> 420.                    <telerikInput:RadComboBox IsEditable="False" 421.                                              Grid.Column="1" 422.                                              Grid.Row="1" 423.                                              Height="24" 424.                                              VerticalAlignment="Center" 425.                                              ItemsSource="{Binding Source={StaticResource DataContextProxy}, Path=DataSource.JobsList}" 426.                                              SelectedValue="{Binding PostingID, Mode=TwoWay}" 427.                                              SelectedValuePath="PostingID" 428.                                              DisplayMemberPath="JobTitle"/> 429.                </Grid> 430.                    <!-- Resources --> 431.                <Grid x:Name="ResourcesLayout" 432.                      Grid.Row="7" 433.                      Grid.Column="0" 434.                      Grid.ColumnSpan="2" 435.                      MaxHeight="130" 436.                      Margin="20,5,20,0"> 437.                    <Border Margin="0" 438.                            BorderThickness="1" 439.                            BorderBrush="{StaticResource GenericShallowBorderBrush}" 440.                            Visibility="{Binding ElementName=ResourcesScrollViewer, Path=ComputedVerticalScrollBarVisibility}"></Border> 441.                    <ScrollViewer x:Name="ResourcesScrollViewer" 442.                                  IsTabStop="false" 443.                                  Grid.Row="6" 444.                                  Grid.Column="0" 445.                                  Grid.ColumnSpan="2" 446.                                  Margin="1" 447.                                  telerik:StyleManager.Theme="{StaticResource Theme}" 448.                                  VerticalScrollBarVisibility="Auto"> 449.                        <scheduler:ResourcesItemsControl x:Name="PART_Resources" 450.                                                         HorizontalAlignment="Left" 451.                                                         Padding="0,2,0,5" 452.                                                         IsTabStop="false" 453.                                                         ItemsSource="{TemplateBinding ResourceTypeModels}" 454.                                                         ItemTemplateSelector="{StaticResource ItemTemplateSelector}" /> 455.                    </ScrollViewer> 456.                </Grid> 457.                <StackPanel x:Name="FooterControls" 458.                            Margin="5 10 10 10" 459.                            Grid.Row="8" 460.                            Grid.Column="1" 461.                            HorizontalAlignment="Left" 462.                            Orientation="Horizontal"> 463.                    <telerik:RadButton x:Name="OKButton" 464.                                       Margin="5" 465.                                       Padding="10 0" 466.                                       MinWidth="80" 467.                                       Command="telerikScheduler:RadSchedulerCommands.SaveAppointment" 468.                                       telerik:StyleManager.Theme="{StaticResource Theme}" 469.                                       telerikNavigation:RadWindow.ResponseButton="Accept" 470.                                       telerik:LocalizationManager.ResourceKey="SaveAndCloseCommandText"> 471.                    </telerik:RadButton> 472.                    <telerik:RadButton x:Name="CancelButton" 473.                                       Margin="5" 474.                                       Padding="10 0" 475.                                       MinWidth="80" 476.                                       telerik:LocalizationManager.ResourceKey="Cancel" 477.                                       telerik:StyleManager.Theme="{StaticResource Theme}" 478.                                       telerikNavigation:RadWindow.ResponseButton="Cancel" 479.                                       Command="telerik:WindowCommands.Close"> 480.                    </telerik:RadButton> 481.                </StackPanel> 482.            </Grid> 483.            <vsm:VisualStateManager.VisualStateGroups> 484.                <vsm:VisualStateGroup x:Name="RecurrenceRuleState"> 485.                    <vsm:VisualState x:Name="RecurrenceRuleIsNull"> 486.                        <Storyboard> 487.                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="StartDateTime" 488.                                                           Storyboard.TargetProperty="IsEnabled" 489.                                                           Duration="0"> 490.                                <DiscreteObjectKeyFrame KeyTime="0" 491.                                                        Value="True" /> 492.                            </ObjectAnimationUsingKeyFrames> 493.                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="EndDateTime" 494.                                                           Storyboard.TargetProperty="IsEnabled" 495.                                                           Duration="0"> 496.                                <DiscreteObjectKeyFrame KeyTime="0" 497.                                                        Value="True" /> 498.                            </ObjectAnimationUsingKeyFrames> 499.                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="AllDayEventCheckbox" 500.                                                           Storyboard.TargetProperty="IsEnabled" 501.                                                           Duration="0"> 502.                                <DiscreteObjectKeyFrame KeyTime="0" 503.                                                        Value="True" /> 504.                            </ObjectAnimationUsingKeyFrames> 505.                        </Storyboard> 506.                    </vsm:VisualState> 507.                    <vsm:VisualState x:Name="RecurrenceRuleIsNotNull"> 508.                        <Storyboard> 509.                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="StartDateTime" 510.                                                           Storyboard.TargetProperty="IsEnabled" 511.                                                           Duration="0"> 512.                                <DiscreteObjectKeyFrame KeyTime="0" 513.                                                        Value="False" /> 514.                            </ObjectAnimationUsingKeyFrames> 515.                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="EndDateTime" 516.                                                           Storyboard.TargetProperty="IsEnabled" 517.                                                           Duration="0"> 518.                                <DiscreteObjectKeyFrame KeyTime="0" 519.                                                        Value="False" /> 520.                            </ObjectAnimationUsingKeyFrames> 521.                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="AllDayEventCheckbox" 522.                                                           Storyboard.TargetProperty="IsEnabled" 523.                                                           Duration="0"> 524.                                <DiscreteObjectKeyFrame KeyTime="0" 525.                                                        Value="False" /> 526.                            </ObjectAnimationUsingKeyFrames> 527.                        </Storyboard> 528.                    </vsm:VisualState> 529.                </vsm:VisualStateGroup> 530.            </vsm:VisualStateManager.VisualStateGroups> 531.        </StackPanel> 532.    </ControlTemplate> 533.    <DataTemplate x:Key="AppointmentDialogWindowHeaderDataTemplate"> 534.        <StackPanel Orientation="Horizontal" 535.                    MaxWidth="400"> 536.            <TextBlock telerik:LocalizationManager.ResourceKey="Event" 537.                       Visibility="{Binding Appointment.IsAllDayEvent, Converter={StaticResource BooleanToVisibilityConverter}}" /> 538.            <TextBlock telerik:LocalizationManager.ResourceKey="Appointment" 539.                       Visibility="{Binding Appointment.IsAllDayEvent, Converter={StaticResource InvertedBooleanToVisibilityConverter}}" /> 540.            <TextBlock Text=" - " /> 541.            <TextBlock x:Name="SubjectTextBlock" 542.                       Visibility="{Binding Appointment.Subject, Converter={StaticResource NullToVisibilityConverter}}" 543.                       Text="{Binding Appointment.Subject}" /> 544.            <TextBlock telerik:LocalizationManager.ResourceKey="Untitled" 545.                       Visibility="{Binding Appointment.Subject, Converter={StaticResource InvertedNullToVisibilityConverter}}" /> 546.        </StackPanel> 547.    </DataTemplate> 548.    <Style x:Key="EditAppointmentStyle" 549.           TargetType="telerikScheduler:AppointmentDialogWindow"> 550.        <Setter Property="IconTemplate" 551.                Value="{StaticResource IconDataEditTemplate}" /> 552.        <Setter Property="HeaderTemplate" 553.                Value="{StaticResource AppointmentDialogWindowHeaderDataTemplate}" /> 554.        <Setter Property="Background" 555.                Value="{StaticResource DialogWindowBackground}" /> 556.        <Setter Property="Template" 557.                Value="{StaticResource EditAppointmentTemplate}" /> 558.    </Style> 559.</UserControl.Resources> The first line there is the DataContextProxy I mentioned previously- we use that again to work a bit of magic in this template. Where we start getting into the dialog in question is line 132, but line 407 is where things start getting interesting.  The ItemsSource is pointing at a list that exists in my ViewModel (or code-behind, if it is used as a DataContext), the SelectedValue is the item I am actually binding from the applicant (note the TwoWay binding), and SelectedValuePath and DisplayMemberPath ensure the proper applicant is being displayed from the collection.  You will also see similar starting on line 420 where I do the same for the Jobs we'll be displaying. Just to wrap-up the Xaml, here's the RadScheduler declaraction that ties this all together and will be the main focus of our view: 01.<telerikScheduler:RadScheduler x:Name="xJobsScheduler" 02.                  Grid.Row="1" 03.                  Grid.Column="1" 04.                  Width="800" 05.                  MinWidth="600" 06.                  Height="500" 07.                  MinHeight="300" 08.                  AppointmentsSource="{Binding Interviews}" 09.                  EditAppointmentStyle="{StaticResource EditAppointmentStyle}" 10.                  command:AppointmentAddedEventClass.Command="{Binding AddAppointmentCommand}" 11.                  command:ApptCreatedEventClass.Command="{Binding ApptCreatingCommand}" 12.                  command:ApptEditedEventClass.Command="{Binding ApptEditedCommand}" 13.                  command:ApptDeletedEventClass.Command="{Binding ApptDeletedCommand}"> 14.</telerikScheduler:RadScheduler> Now, we get to the ViewModel and what it takes to get that rigged up.  And for those of you who remember the jobs post, those command:s in the Xaml are pointing to attached behavior commands that reproduce the respective events.  This becomes very handy when we're setting up the code-behind version. ;) ViewModel I've been liking this approach so far, so I'm going to put the entire ViewModel here and then go into the lines of interest.  Of course, feel free to ask me questions about anything that isn't clear (by line number, ideally) so I can help out if I have missed anything important: 001.public class SchedulerViewModel : ViewModelBase 002.{ 003.    private readonly IEventAggregator eventAggregator; 004.    private readonly IRegionManager regionManager; 005.   006.    public RecruitingContext context; 007.   008.    private ObservableItemCollection<InterviewAppointment> _interviews = new ObservableItemCollection<InterviewAppointment>(); 009.    public ObservableItemCollection<InterviewAppointment> Interviews 010.    { 011.        get { return _interviews; } 012.        set 013.        { 014.            if (_interviews != value) 015.            { 016.                _interviews = value; 017.                NotifyChanged("Interviews"); 018.            } 019.        } 020.    } 021.   022.    private QueryableCollectionView _jobsList; 023.    public QueryableCollectionView JobsList 024.    { 025.        get { return this._jobsList; } 026.        set 027.        { 028.            if (this._jobsList != value) 029.            { 030.                this._jobsList = value; 031.                this.NotifyChanged("JobsList"); 032.            } 033.        } 034.    } 035.   036.    private QueryableCollectionView _applicantList; 037.    public QueryableCollectionView ApplicantList 038.    { 039.        get { return _applicantList; } 040.        set 041.        { 042.            if (_applicantList != value) 043.            { 044.                _applicantList = value; 045.                NotifyChanged("ApplicantList"); 046.            } 047.        } 048.    } 049.   050.    public DelegateCommand<object> AddAppointmentCommand { get; set; } 051.    public DelegateCommand<object> ApptCreatingCommand { get; set; } 052.    public DelegateCommand<object> ApptEditedCommand { get; set; } 053.    public DelegateCommand<object> ApptDeletedCommand { get; set; } 054.   055.    public SchedulerViewModel(IEventAggregator eventAgg, IRegionManager regionmanager) 056.    { 057.        // set Unity items 058.        this.eventAggregator = eventAgg; 059.        this.regionManager = regionmanager; 060.   061.        // load our context 062.        context = new RecruitingContext(); 063.        LoadOperation<Interview> loadOp = context.Load(context.GetInterviewsQuery()); 064.        loadOp.Completed += new EventHandler(loadOp_Completed); 065.   066.        this._jobsList = new QueryableCollectionView(context.JobPostings); 067.        context.Load(context.GetJobPostingsQuery()); 068.   069.        this._applicantList = new QueryableCollectionView(context.Applicants); 070.        context.Load(context.GetApplicantsQuery()); 071.   072.        AddAppointmentCommand = new DelegateCommand<object>(this.AddAppt); 073.        ApptCreatingCommand = new DelegateCommand<object>(this.ApptCreating); 074.        ApptEditedCommand = new DelegateCommand<object>(this.ApptEdited); 075.        ApptDeletedCommand = new DelegateCommand<object>(this.ApptDeleted); 076.   077.    } 078.   079.    void loadOp_Completed(object sender, EventArgs e) 080.    { 081.        LoadOperation loadop = sender as LoadOperation; 082.   083.        foreach (var ent in loadop.Entities) 084.        { 085.            _interviews.Add(EntityToAppointment(ent as Interview)); 086.        } 087.    } 088.   089.    #region Appointment Adding 090.   091.    public void AddAppt(object obj) 092.    { 093.        // now we have a new InterviewAppointment to add to our QCV :) 094.        InterviewAppointment newInterview = obj as InterviewAppointment; 095.   096.        this.context.Interviews.Add(AppointmentToEntity(newInterview)); 097.        this.context.SubmitChanges((s) => 098.        { 099.            ActionHistory myAction = new ActionHistory(); 100.            myAction.InterviewID = newInterview.InterviewID; 101.            myAction.PostingID = newInterview.PostingID; 102.            myAction.ApplicantID = newInterview.ApplicantID; 103.            myAction.Description = String.Format("Interview with {0} has been created by {1}", newInterview.ApplicantID.ToString(), "default user"); 104.            myAction.TimeStamp = DateTime.Now; 105.            eventAggregator.GetEvent<AddActionEvent>().Publish(myAction); 106.        } 107.            , null); 108.    } 109.   110.    public void ApptCreating(object obj) 111.    { 112.        // handled in the behavior, just a placeholder to ensure it runs :) 113.    } 114.   115.    #endregion 116.   117.    #region Appointment Editing 118.   119.    public void ApptEdited(object obj) 120.    { 121.        Interview editedInterview = (from x in context.Interviews 122.                            where x.InterviewID == (obj as InterviewAppointment).InterviewID 123.                            select x).SingleOrDefault(); 124.   125.        CopyAppointmentEdit(editedInterview, obj as InterviewAppointment); 126.   127.        context.SubmitChanges((s) => { 128.            ActionHistory myAction = new ActionHistory(); 129.            myAction.InterviewID = editedInterview.InterviewID; 130.            myAction.PostingID = editedInterview.PostingID; 131.            myAction.ApplicantID = editedInterview.ApplicantID; 132.            myAction.Description = String.Format("Interview with {0} has been modified by {1}", editedInterview.ApplicantID.ToString(), "default user"); 133.            myAction.TimeStamp = DateTime.Now; 134.            eventAggregator.GetEvent<AddActionEvent>().Publish(myAction); } 135.            , null); 136.    } 137.   138.    #endregion 139.   140.    #region Appointment Deleting 141.   142.    public void ApptDeleted(object obj) 143.    { 144.        Interview deletedInterview = (from x in context.Interviews 145.                                      where x.InterviewID == (obj as InterviewAppointment).InterviewID 146.                                      select x).SingleOrDefault(); 147.   148.        context.Interviews.Remove(deletedInterview); 149.        context.SubmitChanges((s) => 150.        { 151.            ActionHistory myAction = new ActionHistory(); 152.            myAction.InterviewID = deletedInterview.InterviewID; 153.            myAction.PostingID = deletedInterview.PostingID; 154.            myAction.ApplicantID = deletedInterview.ApplicantID; 155.            myAction.Description = String.Format("Interview with {0} has been deleted by {1}", deletedInterview.ApplicantID.ToString(), "default user"); 156.            myAction.TimeStamp = DateTime.Now; 157.            eventAggregator.GetEvent<AddActionEvent>().Publish(myAction); 158.        } 159.            , null); 160.    } 161.   162.    #endregion 163.   164.    #region Appointment Helpers :) 165.   166.    public Interview AppointmentToEntity(InterviewAppointment ia) 167.    { 168.        Interview newInterview = new Interview(); 169.        newInterview.Subject = ia.Subject; 170.        newInterview.Body = ia.Body; 171.        newInterview.Start = ia.Start; 172.        newInterview.End = ia.End; 173.        newInterview.ApplicantID = ia.ApplicantID; 174.        newInterview.PostingID = ia.PostingID; 175.        newInterview.InterviewID = ia.InterviewID; 176.   177.        return newInterview; 178.    } 179.   180.    public InterviewAppointment EntityToAppointment(Interview ia) 181.    { 182.        InterviewAppointment newInterview = new InterviewAppointment(); 183.        newInterview.Subject = ia.Subject; 184.        newInterview.Body = ia.Body; 185.        newInterview.Start = ia.Start; 186.        newInterview.End = ia.End; 187.        newInterview.ApplicantID = ia.ApplicantID; 188.        newInterview.PostingID = ia.PostingID; 189.        newInterview.InterviewID = ia.InterviewID; 190.   191.        return newInterview; 192.    } 193.   194.    public void CopyAppointmentEdit(Interview entityInterview, InterviewAppointment appointmentInterview) 195.    { 196.        entityInterview.Subject = appointmentInterview.Subject; 197.        entityInterview.Body = appointmentInterview.Body; 198.        entityInterview.Start = appointmentInterview.Start; 199.        entityInterview.End = appointmentInterview.End; 200.        entityInterview.ApplicantID = appointmentInterview.ApplicantID; 201.        entityInterview.PostingID = appointmentInterview.PostingID; 202.    } 203.   204.    #endregion 205.} One thing we're doing here which you won't see in any of the other ViewModels is creating a duplicate collection.  I know this is something which will be fixed down the line for using RadScheduler, simplifying this process, but with WCF RIA changing as it does I wanted to ensure functionality would remain consistent as I continued development on this application.  So, I do a little bit of duplication, but for the greater good.  This all takes place starting on line 79, so for every entity that comes back we add it to the collection that is bound to RadScheduler.  Otherwise, the DelegateCommands that you see correspond directly to the events they are named after.  In each case, rather than sending over the full event arguments, I just send in the appointment in question (coming through as the object obj in all cases) so I can add (line 91), edit (line 119), and delete appointments (line 142) like normal.  This just ensures they get updated back to my database.  Also, the one bit of code you won't see is for the Appointment Creating (line 110) event- that is because in the command I've created I simply make the replacement I need to: 1.void element_AppointmentCreating(object sender, AppointmentCreatingEventArgs e) 2.{ 3.    e.NewAppointment = new InterviewAppointment(); 4.    base.ExecuteCommand(); 5.} And the ViewModel is none the wiser, the appointments just work as far as it is concerned since as they are created they become InterviewAppointments.  End result?  I've customized my EditAppointmentDialog as follows: And adding, editing, and deleting appointments works like a charm.  I can even 'edit' by moving appointments around RadScheduler, so as they are dropped into a timeslot they perform their full edit routine and things get updated. And then, the Code-Behind Version Perhaps the thing I like the most about doing one then the other is I get to steal 90% or more of the code from the MVVM version.  For example, the only real changes to the Code-Behind Xaml file exist in the control declaration, in which I use events instead of attached-behavior-event-commands: 01.<telerikScheduler:RadScheduler x:Name="xJobsScheduler" 02.                  Grid.Row="1" 03.                  Grid.Column="1" 04.                  Width="800" 05.                  MinWidth="600" 06.                  Height="500" 07.                  MinHeight="300" 08.                  EditAppointmentStyle="{StaticResource EditAppointmentStyle}" 09.                  AppointmentAdded="xJobsScheduler_AppointmentAdded" 10.                  AppointmentCreating="xJobsScheduler_AppointmentCreating" 11.                  AppointmentEdited="xJobsScheduler_AppointmentEdited" 12.                  AppointmentDeleted="xJobsScheduler_AppointmentDeleted"> 13.</telerikScheduler:RadScheduler> Easy, right?  Otherwise, all the same styling in UserControl.Resources was re-used, right down to the DataContextProxy that lets us bind to a collection from our viewmodel (in this case, our code-behind) to use within the DataTemplate.  The code conversion gets even easier, as I could literally copy and paste almost everything from the ViewModel to my Code-Behind, just a matter of pasting the right section into the right event.  Here's the code-behind as proof: 001.public partial class SchedulingView : UserControl, INotifyPropertyChanged 002.{ 003.    public RecruitingContext context; 004.   005.    private QueryableCollectionView _jobsList; 006.    public QueryableCollectionView JobsList 007.    { 008.        get { return this._jobsList; } 009.        set 010.        { 011.            if (this._jobsList != value) 012.            { 013.                this._jobsList = value; 014.                this.NotifyChanged("JobsList"); 015.            } 016.        } 017.    } 018.   019.    private QueryableCollectionView _applicantList; 020.    public QueryableCollectionView ApplicantList 021.    { 022.        get { return _applicantList; } 023.        set 024.        { 025.            if (_applicantList != value) 026.            { 027.                _applicantList = value; 028.                NotifyChanged("ApplicantList"); 029.            } 030.        } 031.    } 032.   033.    private ObservableItemCollection<InterviewAppointment> _interviews = new ObservableItemCollection<InterviewAppointment>(); 034.    public ObservableItemCollection<InterviewAppointment> Interviews 035.    { 036.        get { return _interviews; } 037.        set 038.        { 039.            if (_interviews != value) 040.            { 041.                _interviews = value; 042.                NotifyChanged("Interviews"); 043.            } 044.        } 045.    } 046.   047.    public SchedulingView() 048.    { 049.        InitializeComponent(); 050.   051.        this.DataContext = this; 052.   053.        this.Loaded += new RoutedEventHandler(SchedulingView_Loaded); 054.    } 055.   056.    void SchedulingView_Loaded(object sender, RoutedEventArgs e) 057.    { 058.        this.xJobsScheduler.AppointmentsSource = Interviews; 059.   060.        context = new RecruitingContext(); 061.           062.        LoadOperation loadop = context.Load(context.GetInterviewsQuery()); 063.        loadop.Completed += new EventHandler(loadop_Completed); 064.   065.        this._applicantList = new QueryableCollectionView(context.Applicants); 066.        context.Load(context.GetApplicantsQuery()); 067.   068.        this._jobsList = new QueryableCollectionView(context.JobPostings); 069.        context.Load(context.GetJobPostingsQuery()); 070.    } 071.   072.    void loadop_Completed(object sender, EventArgs e) 073.    { 074.        LoadOperation loadop = sender as LoadOperation; 075.   076.        _interviews.Clear(); 077.   078.        foreach (var ent in loadop.Entities) 079.        { 080.            _interviews.Add(EntityToAppointment(ent as Interview)); 081.        } 082.    } 083.   084.    private void xJobsScheduler_AppointmentAdded(object sender, Telerik.Windows.Controls.AppointmentAddedEventArgs e) 085.    { 086.        // now we have a new InterviewAppointment to add to our QCV :) 087.        InterviewAppointment newInterview = e.Appointment as InterviewAppointment; 088.   089.        this.context.Interviews.Add(AppointmentToEntity(newInterview)); 090.        this.context.SubmitChanges((s) => 091.        { 092.            ActionHistory myAction = new ActionHistory(); 093.            myAction.InterviewID = newInterview.InterviewID; 094.            myAction.PostingID = newInterview.PostingID; 095.            myAction.ApplicantID = newInterview.ApplicantID; 096.            myAction.Description = String.Format("Interview with {0} has been created by {1}", newInterview.ApplicantID.ToString(), "default user"); 097.            myAction.TimeStamp = DateTime.Now; 098.            context.ActionHistories.Add(myAction); 099.            context.SubmitChanges(); 100.        } 101.            , null); 102.    } 103.   104.    private void xJobsScheduler_AppointmentCreating(object sender, Telerik.Windows.Controls.AppointmentCreatingEventArgs e) 105.    { 106.        e.NewAppointment = new InterviewAppointment(); 107.    } 108.   109.    private void xJobsScheduler_AppointmentEdited(object sender, Telerik.Windows.Controls.AppointmentEditedEventArgs e) 110.    { 111.        Interview editedInterview = (from x in context.Interviews 112.                                     where x.InterviewID == (e.Appointment as InterviewAppointment).InterviewID 113.                                     select x).SingleOrDefault(); 114.   115.        CopyAppointmentEdit(editedInterview, e.Appointment as InterviewAppointment); 116.   117.        context.SubmitChanges((s) => 118.        { 119.            ActionHistory myAction = new ActionHistory(); 120.            myAction.InterviewID = editedInterview.InterviewID; 121.            myAction.PostingID = editedInterview.PostingID; 122.            myAction.ApplicantID = editedInterview.ApplicantID; 123.            myAction.Description = String.Format("Interview with {0} has been modified by {1}", editedInterview.ApplicantID.ToString(), "default user"); 124.            myAction.TimeStamp = DateTime.Now; 125.            context.ActionHistories.Add(myAction); 126.            context.SubmitChanges(); 127.        } 128.            , null); 129.    } 130.   131.    private void xJobsScheduler_AppointmentDeleted(object sender, Telerik.Windows.Controls.AppointmentDeletedEventArgs e) 132.    { 133.        Interview deletedInterview = (from x in context.Interviews 134.                                      where x.InterviewID == (e.Appointment as InterviewAppointment).InterviewID 135.                                      select x).SingleOrDefault(); 136.   137.        context.Interviews.Remove(deletedInterview); 138.        context.SubmitChanges((s) => 139.        { 140.            ActionHistory myAction = new ActionHistory(); 141.            myAction.InterviewID = deletedInterview.InterviewID; 142.            myAction.PostingID = deletedInterview.PostingID; 143.            myAction.ApplicantID = deletedInterview.ApplicantID; 144.            myAction.Description = String.Format("Interview with {0} has been deleted by {1}", deletedInterview.ApplicantID.ToString(), "default user"); 145.            myAction.TimeStamp = DateTime.Now; 146.            context.ActionHistories.Add(myAction); 147.            context.SubmitChanges(); 148.        } 149.            , null); 150.    } 151.   152.    #region Appointment Helpers :) 153.   154.    public Interview AppointmentToEntity(InterviewAppointment ia) 155.    { 156.        Interview newInterview = new Interview(); 157.        newInterview.Subject = ia.Subject; 158.        newInterview.Body = ia.Body; 159.        newInterview.Start = ia.Start; 160.        newInterview.End = ia.End; 161.        newInterview.ApplicantID = ia.ApplicantID; 162.        newInterview.PostingID = ia.PostingID; 163.        newInterview.InterviewID = ia.InterviewID; 164.   165.        return newInterview; 166.    } 167.   168.    public InterviewAppointment EntityToAppointment(Interview ia) 169.    { 170.        InterviewAppointment newInterview = new InterviewAppointment(); 171.        newInterview.Subject = ia.Subject; 172.        newInterview.Body = ia.Body; 173.        newInterview.Start = ia.Start; 174.        newInterview.End = ia.End; 175.        newInterview.ApplicantID = ia.ApplicantID; 176.        newInterview.PostingID = ia.PostingID; 177.        newInterview.InterviewID = ia.InterviewID; 178.   179.        return newInterview; 180.    } 181.   182.    public void CopyAppointmentEdit(Interview entityInterview, InterviewAppointment appointmentInterview) 183.    { 184.        entityInterview.Subject = appointmentInterview.Subject; 185.        entityInterview.Body = appointmentInterview.Body; 186.        entityInterview.Start = appointmentInterview.Start; 187.        entityInterview.End = appointmentInterview.End; 188.        entityInterview.ApplicantID = appointmentInterview.ApplicantID; 189.        entityInterview.PostingID = appointmentInterview.PostingID; 190.    } 191.   192.    #endregion 193.   194.    #region INotifyPropertyChanged Members 195.   196.    public event PropertyChangedEventHandler PropertyChanged; 197.   198.    public void NotifyChanged(string propertyName) 199.    { 200.        if (string.IsNullOrEmpty(propertyName)) 201.            throw new ArgumentException("propertyName"); 202.   203.        PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); 204.    } 205.   206.    #endregion 207.} Nice... right? :) One really important thing to note as well.  See on line 51 where I set the DataContext before the Loaded event?  This is super important, as if you don't have this set before the usercontrol is loaded, the DataContextProxy has no context to use and your EditAppointmentDialog Job/Applicant dropdowns will be blank and empty.  Trust me on this, took a little bit of debugging to figure out that by setting the DataContext post-loaded would only lead to disaster and frustration.  Otherwise, the only other real difference is that instead of sending an ActionHistory item through an event to get added to the database and saved, I do those right in the callback from submitting.  The Result Again, I only have to post one picture because these bad boys used nearly identical code for both the MVVM and the code-behind views, so our end result is... So what have we learned here today?  One, for the most part this MVVM thing is somewhat easy.  Yeah, you sometimes have to write a bunch of extra code, but with the help of a few useful snippits you can turn the process into a pretty streamlined little workflow.  Heck, this story gets even easier as you can see in this blog post by Michael Washington- specifically run a find on 'InvokeCommandAction' and you'll see the section regarding the command on TreeView in Blend 4.  Brilliant!  MVVM never looked so sweet! Otherwise, it is business as usual with RadScheduler for Silverlight whichever path you're choosing for your development.  Between now and the next post, I'll be cleaning up styles a bit (those RadComboBoxes are a little too close to my labels!) and adding some to the RowDetailsViews for Applicants and Jobs, so you can see all the info for an appointment in the dropdown tab view.  Otherwise, we're about ready to call a wrap on this oneDid you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Silverlight Recruiting Application Part 6 - Adding an Interview Scheduling Module/View

  Between the last post and this one I went ahead and carried the ideas for the Jobs module and view into the Applicants module and view- they're both doing more or less the same thing, except with different objects being at their core.  Made for an easy cut-and-paste operation with a few items being switched from one to another.  Now that we have the ability to add postings and applicants, wouldn't it be nice if we could schedule an interview?  Of course it would! Scheduling Module I think you get the drift from previous posts that these project structures start looking somewhat similar.  The interview scheduling module is no different than the rest- it gets a SchedulingModule.cs file at the root that inherits from IModule, and there is a single SchedulerView.xsml and SchedulerViewModel.cs setup for our V+VM.  We have one unique concern as we enter into this- RadScheduler deals with AppointmentsSource, not ItemsSource, so there are some special considerations to take into account when planning this module. First, I need something which inherits from AppointmentBase.  This is the core of the RadScheduler appointment, and if you are planning to do any form of custom appointment, you'll want it to inherit from this.  Then you can add-on functionality as needed.  Here is my addition to the mix, the InterviewAppointment: 01.public class InterviewAppointment : AppointmentBase 02.{ 03.    private int _applicantID; 04.    public int ApplicantID 05.    { 06.        get { return this._applicantID; } 07.        set 08.        { 09.            if (_applicantID != value) 10.            { 11.                _applicantID = value; 12.                OnPropertyChanged("ApplicantID"); 13.            } 14.        } 15.    } 16.   17.    private int _postingID; 18.    public int PostingID 19.    { 20.        get { return _postingID; } 21.        set 22.        { 23.            if (_postingID != value) 24.            { 25.                _postingID = value; 26.                OnPropertyChanged("PostingID"); 27.            } 28.        } 29.    } 30.   31.    private string _body; 32.    public string Body 33.    { 34.        get { return _body; } 35.        set 36.        { 37.            if (_body != value) 38.            { 39.                _body = value; 40.                OnPropertyChanged("Body"); 41.            } 42.        } 43.    } 44.   45.    private int _interviewID; 46.    public int InterviewID 47.    { 48.        get { return _interviewID; } 49.        set 50.        { 51.            if (_interviewID != value) 52.            { 53.                _interviewID = value; 54.                OnPropertyChanged("InterviewID"); 55.            } 56.        } 57.    } 58.   59.    public override IAppointment Copy() 60.    { 61.        IAppointment appointment = new InterviewAppointment(); 62.        appointment.CopyFrom(this);             63.        return appointment; 64.    } 65.   66.    public override void CopyFrom(IAppointment other) 67.    {             68.        base.CopyFrom(other); 69.        var appointment = other as InterviewAppointment; 70.        if (appointment != null) 71.        { 72.            ApplicantID = appointment.ApplicantID; 73.            PostingID = appointment.PostingID; 74.            Body = appointment.Body; 75.            InterviewID = appointment.InterviewID; 76.        } 77.    } 78.} Nothing too exciting going on here, we just make sure that our custom fields are persisted (specifically set in CopyFrom at the bottom) and notifications are fired- otherwise this ends up exactly like the standard appointment as far as interactions, etc.  But if we've got custom appointment items... that also means we need to customize what our appointment dialog window will look like. Customizing the Edit Appointment Dialog This initially sounds a lot more intimidating than it really is.  The first step here depends on what you're dealing with for theming, but for ease of everything I went ahead and extracted my templates in Blend for RadScheduler so I could modify it as I pleased.  For the faint of heart, the RadScheduler template is a few thousand lines of goodness since there are some very complex things going on in that control.  I've gone ahead and trimmed down the template parts I don't need as much as possible, so what is left is all that is relevant to the Edit Appointment Dialog.  Here's the resulting Xaml, with line numbers, so I can explain further: 001.<UserControl.Resources> 002.    <!-- begin Necessary Windows 7 Theme Resources for EditAppointmentTemplate --> 003.    <helpers:DataContextProxy x:Key="DataContextProxy" /> 004.       005.    <telerik:Windows7Theme x:Key="Theme" /> 006.    <SolidColorBrush x:Key="DialogWindowBackground" 007.                     Color="White" /> 008.    <SolidColorBrush x:Key="CategorySelectorBorderBrush" 009.                     Color="#FFB1B1B1" /> 010.    <LinearGradientBrush x:Key="RadToolBar_InnerBackground" 011.                         EndPoint="0.5,1" 012.                         StartPoint="0.5,0"> 013.        <GradientStop Color="#FFFDFEFF" 014.                      Offset="0" /> 015.        <GradientStop Color="#FFDDE9F7" 016.                      Offset="1" /> 017.        <GradientStop Color="#FFE6F0FA" 018.                      Offset="0.5" /> 019.        <GradientStop Color="#FFDCE6F4" 020.                      Offset="0.5" /> 021.    </LinearGradientBrush> 022.    <Style x:Key="FormElementTextBlockStyle" 023.           TargetType="TextBlock"> 024.        <Setter Property="HorizontalAlignment" 025.                Value="Right" /> 026.        <Setter Property="VerticalAlignment" 027.                Value="Top" /> 028.        <Setter Property="Margin" 029.                Value="15, 15, 0, 2" /> 030.    </Style> 031.    <Style x:Key="FormElementStyle" 032.           TargetType="FrameworkElement"> 033.        <Setter Property="Margin" 034.                Value="10, 10, 0, 2" /> 035.    </Style> 036.    <SolidColorBrush x:Key="GenericShallowBorderBrush" 037.                     Color="#FF979994" /> 038.    <telerik:BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter" /> 039.    <telerikScheduler:ImportanceToBooleanConverter x:Key="ImportanceToBooleanConverter" /> 040.    <telerikScheduler:NullToVisibilityConverter x:Key="NullToVisibilityConverter" /> 041.    <telerikScheduler:InvertedNullToVisibilityConverter x:Key="InvertedNullToVisibilityConverter" /> 042.    <scheduler:ResourcesSeparatorConverter x:Key="ResourcesSeparatorConverter" /> 043.    <DataTemplate x:Key="IconDataEditTemplate"> 044.        <Image Source="/Telerik.Windows.Controls.Scheduler;component/Themes/Office/Images/cal.png" 045.               Margin="3,3,0,0" 046.               Width="16" 047.               Height="16" /> 048.    </DataTemplate> 049.    <DataTemplate x:Key="SingleSelectionTemplate"> 050.        <Grid VerticalAlignment="Stretch" 051.              HorizontalAlignment="Stretch"> 052.            <Grid.RowDefinitions> 053.                <RowDefinition Height="Auto" /> 054.            </Grid.RowDefinitions> 055.            <Grid.ColumnDefinitions> 056.                <ColumnDefinition Width="Auto" 057.                                  MinWidth="84" /> 058.                <ColumnDefinition Width="Auto" 059.                                  MinWidth="200" /> 060.            </Grid.ColumnDefinitions> 061.            <TextBlock x:Name="SelectionNameLabel" 062.                       Margin="0,13,4,2" 063.                       Text="{Binding ResourceType.DisplayName}" 064.                       Style="{StaticResource FormElementTextBlockStyle}" 065.                       Grid.Column="0" /> 066.            <telerikInput:RadComboBox ItemsSource="{Binding ResourceItems}" 067.                                      Width="185" 068.                                      Margin="5,10,20,2" 069.                                      HorizontalAlignment="Left" 070.                                      Grid.Column="1" 071.                                      ClearSelectionButtonVisibility="Visible" 072.                                      ClearSelectionButtonContent="Clear All" 073.                                      DisplayMemberPath="Resource.DisplayName" 074.                                      telerik:StyleManager.Theme="{StaticResource Theme}" 075.                                      SelectedItem="{Binding SelectedItem, Mode=TwoWay}" /> 076.        </Grid> 077.    </DataTemplate> 078.    <DataTemplate x:Key="MultipleSelectionTemplate"> 079.        <Grid VerticalAlignment="Stretch" 080.              HorizontalAlignment="Stretch"> 081.            <Grid.RowDefinitions> 082.                <RowDefinition Height="Auto" /> 083.            </Grid.RowDefinitions> 084.            <Grid.ColumnDefinitions> 085.                <ColumnDefinition Width="Auto" 086.                                  MinWidth="84" /> 087.                <ColumnDefinition Width="Auto" 088.                                  MinWidth="200" /> 089.            </Grid.ColumnDefinitions> 090.            <TextBlock x:Name="SelectionNameLabel" 091.                       Grid.Column="0" 092.                       Text="{Binding ResourceType.DisplayName}" 093.                       Margin="0,13,4,2" 094.                       Style="{StaticResource FormElementTextBlockStyle}" /> 095.            <telerikInput:RadComboBox Grid.Column="1" 096.                                      Width="185" 097.                                      HorizontalAlignment="Left" 098.                                      Margin="5,10,20,2" 099.                                      ItemsSource="{Binding ResourceItems}" 100.                                      SelectedIndex="{Binding SelectedIndex, Mode=TwoWay}" 101.                                      ClearSelectionButtonVisibility="Visible" 102.                                      ClearSelectionButtonContent="Clear All" 103.                                      telerik:StyleManager.Theme="{StaticResource Theme}"> 104.                <telerikInput:RadComboBox.ItemTemplate> 105.                    <DataTemplate> 106.                        <Grid HorizontalAlignment="Stretch" 107.                              VerticalAlignment="Stretch"> 108.                            <CheckBox VerticalAlignment="Center" 109.                                      HorizontalContentAlignment="Stretch" 110.                                      VerticalContentAlignment="Center" 111.                                      IsChecked="{Binding IsChecked, Mode=TwoWay}" 112.                                      Content="{Binding Resource.DisplayName}"> 113.                                <CheckBox.ContentTemplate> 114.                                    <DataTemplate> 115.                                        <TextBlock HorizontalAlignment="Stretch" 116.                                                   VerticalAlignment="Stretch" 117.                                                   Text="{Binding Content, RelativeSource={RelativeSource TemplatedParent}}" /> 118.                                    </DataTemplate> 119.                                </CheckBox.ContentTemplate> 120.                            </CheckBox> 121.                        </Grid> 122.                    </DataTemplate> 123.                </telerikInput:RadComboBox.ItemTemplate> 124.            </telerikInput:RadComboBox> 125.        </Grid> 126.    </DataTemplate> 127.    <scheduler:ResourceTypeTemplateSelector x:Key="ItemTemplateSelector" 128.                                            MultipleSelectionTemplate="{StaticResource MultipleSelectionTemplate}" 129.                                            SingleSelectionTemplate="{StaticResource SingleSelectionTemplate}" /> 130.    <!-- end Necessary Windows 7 Theme Resources for EditAppointmentTemplate -->  131.       132.    <ControlTemplate x:Key="EditAppointmentTemplate" 133.                     TargetType="telerikScheduler:AppointmentDialogWindow"> 134.        <StackPanel Background="{TemplateBinding Background}" 135.                    UseLayoutRounding="True"> 136.            <StackPanel Grid.Row="0" 137.                        Orientation="Horizontal" 138.                        Background="{StaticResource RadToolBar_InnerBackground}" 139.                        Grid.ColumnSpan="2" 140.                        Height="0"> 141.                <!-- Recurrence buttons --> 142.                <Border Margin="1,1,0,0" 143.                        Background="#50000000" 144.                        HorizontalAlignment="Left" 145.                        VerticalAlignment="Center" 146.                        Width="2" 147.                        Height="16"> 148.                    <Border Margin="0,0,1,1" 149.                            Background="#80FFFFFF" 150.                            HorizontalAlignment="Left" 151.                            Width="1" /> 152.                </Border> 153.                <Border Margin="1,1,0,0" 154.                        Background="#50000000" 155.                        HorizontalAlignment="Left" 156.                        VerticalAlignment="Center" 157.                        Width="2" 158.                        Height="16"> 159.                    <Border Margin="0,0,1,1" 160.                            Background="#80FFFFFF" 161.                            HorizontalAlignment="Left" 162.                            Width="1" /> 163.                </Border> 164.                <TextBlock telerik:LocalizationManager.ResourceKey="ShowAs" 165.                           VerticalAlignment="Center" 166.                           Margin="5,0,0,0" /> 167.                <telerikInput:RadComboBox ItemsSource="{TemplateBinding TimeMarkers}" 168.                                          Width="100" 169.                                          Height="20" 170.                                          VerticalAlignment="Center" 171.                                          Margin="5,0,0,0" 172.                                          ClearSelectionButtonVisibility="Visible" 173.                                          ClearSelectionButtonContent="Clear" 174.                                          SelectedItem="{Binding TimeMarker,RelativeSource={RelativeSource TemplatedParent},Mode=TwoWay}" 175.                                          telerik:StyleManager.Theme="{StaticResource Theme}"> 176.                    <telerikInput:RadComboBox.ItemTemplate> 177.                        <DataTemplate> 178.                            <StackPanel Orientation="Horizontal"> 179.                                <Rectangle Fill="{Binding TimeMarkerBrush}" 180.                                           Margin="2" 181.                                           Width="12" 182.                                           Height="12" /> 183.                                <TextBlock Text="{Binding TimeMarkerName}" 184.                                           Margin="2" /> 185.                            </StackPanel> 186.                        </DataTemplate> 187.                    </telerikInput:RadComboBox.ItemTemplate> 188.                </telerikInput:RadComboBox> 189.                <telerik:RadToggleButton x:Name="High" 190.                                         BorderThickness="0" 191.                                         Background="{StaticResource RadToolBar_InnerBackground}" 192.                                         DataContext="{TemplateBinding EditedAppointment}" 193.                                         telerik:StyleManager.Theme="{StaticResource Theme}" 194.                                         IsChecked="{Binding Importance,Mode=TwoWay, Converter={StaticResource ImportanceToBooleanConverter},ConverterParameter=High}" 195.                                         Margin="2,2,0,2" 196.                                         Width="23" 197.                                         Height="23" 198.                                         HorizontalContentAlignment="Center" 199.                                         ToolTipService.ToolTip="High importance" 200.                                         CommandParameter="High" 201.                                         Command="telerikScheduler:RadSchedulerCommands.SetAppointmentImportance"> 202.                    <StackPanel HorizontalAlignment="Center"> 203.                        <Path Stretch="Fill" 204.                              Height="10" 205.                              HorizontalAlignment="Center" 206.                              VerticalAlignment="Top" 207.                              Width="5.451" 208.                              Data="M200.39647,58.840393 C200.39337,58.336426 201.14566,57.683922 202.56244,57.684292 C204.06589,57.684685 204.73764,58.357765 204.72783,58.992363 C205.04649,61.795574 203.04713,64.181099 202.47388,66.133446 C201.93753,64.154961 199.9471,61.560352 200.39647,58.840393 z"> 209.                            <Path.Fill> 210.                                <LinearGradientBrush EndPoint="1.059,0.375" 211.                                                     StartPoint="-0.457,0.519"> 212.                                    <GradientStop Color="#FFFF0606" 213.                                                  Offset="0.609" /> 214.                                    <GradientStop Color="#FFBF0303" 215.                                                  Offset="0.927" /> 216.                                </LinearGradientBrush> 217.                            </Path.Fill> 218.                        </Path> 219.                        <Ellipse Height="3" 220.                                 HorizontalAlignment="Center" 221.                                 Margin="0,-1,0,0" 222.                                 VerticalAlignment="Top" 223.                                 Width="3"> 224.                            <Ellipse.Fill> 225.                                <RadialGradientBrush> 226.                                    <GradientStop Color="#FFFF0606" 227.                                                  Offset="0" /> 228.                                    <GradientStop Color="#FFBF0303" 229.                                                  Offset="1" /> 230.                                </RadialGradientBrush> 231.                            </Ellipse.Fill> 232.                        </Ellipse> 233.                    </StackPanel> 234.                </telerik:RadToggleButton> 235.                <telerik:RadToggleButton x:Name="Low" 236.                                         HorizontalContentAlignment="Center" 237.                                         BorderThickness="0" 238.                                         Background="{StaticResource RadToolBar_InnerBackground}" 239.                                         DataContext="{TemplateBinding EditedAppointment}" 240.                                         IsChecked="{Binding Importance,Mode=TwoWay, Converter={StaticResource ImportanceToBooleanConverter},ConverterParameter=Low}" 241.                                         Margin="0,2,0,2" 242.                                         Width="23" 243.                                         Height="23" 244.                                         ToolTipService.ToolTip="Low importance" 245.                                         CommandParameter="Low" 246.                                         telerik:StyleManager.Theme="{StaticResource Theme}" 247.                                         Command="telerikScheduler:RadSchedulerCommands.SetAppointmentImportance"> 248.                    <Path Stretch="Fill" 249.                          Height="12" 250.                          HorizontalAlignment="Center" 251.                          VerticalAlignment="Top" 252.                          Width="9" 253.                          Data="M222.40353,60.139881 L226.65768,60.139843 L226.63687,67.240196 L229.15347,67.240196 L224.37816,71.394943 L219.65274,67.240196 L222.37572,67.219345 z" 254.                          Stroke="#FF0365A7"> 255.                        <Path.Fill> 256.                            <LinearGradientBrush EndPoint="1.059,0.375" 257.                                                 StartPoint="-0.457,0.519"> 258.                                <GradientStop Color="#FFBBE4FF" /> 259.                                <GradientStop Color="#FF024572" 260.                                              Offset="0.836" /> 261.                                <GradientStop Color="#FF43ADF4" 262.                                              Offset="0.466" /> 263.                            </LinearGradientBrush> 264.                        </Path.Fill> 265.                    </Path> 266.                </telerik:RadToggleButton> 267.            </StackPanel > 268.            <Border DataContext="{TemplateBinding EditedAppointment}" 269.                    Background="{Binding Category.CategoryBrush}" 270.                    Visibility="{Binding Category,Converter={StaticResource NullToVisibilityConverter}}" 271.                    CornerRadius="3" 272.                    Height="20" 273.                    Margin="5,10,5,0"> 274.                <TextBlock Text="{Binding Category.DisplayName}" 275.                           VerticalAlignment="Center" 276.                           Margin="5,0,0,0" /> 277.            </Border> 278.            <Grid VerticalAlignment="Stretch" 279.                  HorizontalAlignment="Stretch" 280.                  DataContext="{TemplateBinding EditedAppointment}" 281.                  Background="{TemplateBinding Background}"> 282.                <Grid.RowDefinitions> 283.                    <RowDefinition Height="Auto" /> 284.                    <RowDefinition Height="Auto" /> 285.                    <RowDefinition Height="Auto" /> 286.                    <RowDefinition Height="Auto" /> 287.                    <RowDefinition Height="Auto" /> 288.                    <RowDefinition Height="Auto" /> 289.                    <RowDefinition Height="Auto" /> 290.                    <RowDefinition Height="Auto" /> 291.                    <RowDefinition Height="Auto" /> 292.                    <RowDefinition Height="Auto" /> 293.                </Grid.RowDefinitions> 294.                <Grid.ColumnDefinitions> 295.                    <ColumnDefinition Width="Auto" 296.                                      MinWidth="100" /> 297.                    <ColumnDefinition Width="Auto" 298.                                      MinWidth="200" /> 299.                </Grid.ColumnDefinitions> 300.                <!-- Subject --> 301.                <TextBlock x:Name="SubjectLabel" 302.                           Grid.Row="0" 303.                           Grid.Column="0" 304.                           Margin="0,15,0,2" 305.                           telerik:LocalizationManager.ResourceKey="Subject" 306.                           Style="{StaticResource FormElementTextBlockStyle}" /> 307.                <TextBox x:Name="Subject" 308.                         Grid.Row="0" 309.                         Grid.Column="1" 310.                         MinHeight="22" 311.                         Padding="4 2" 312.                         Width="340" 313.                         HorizontalAlignment="Left" 314.                         Text="{Binding Subject, Mode=TwoWay}" 315.                         MaxLength="255" 316.                         telerik:StyleManager.Theme="{StaticResource Theme}" 317.                         Margin="10,12,20,2" /> 318.                <!-- Description --> 319.                <TextBlock x:Name="DescriptionLabel" 320.                           Grid.Row="1" 321.                           Grid.Column="0" 322.                           Margin="0,13,0,2" 323.                           telerik:LocalizationManager.ResourceKey="Body" 324.                           Style="{StaticResource FormElementTextBlockStyle}" /> 325.                <TextBox x:Name="Body" 326.                         VerticalAlignment="top" 327.                         Grid.Row="1" 328.                         Grid.Column="1" 329.                         Height="Auto" 330.                         MaxHeight="82" 331.                         Width="340" 332.                         HorizontalAlignment="Left" 333.                         MinHeight="22" 334.                         Padding="4 2" 335.                         TextWrapping="Wrap" 336.                         telerik:StyleManager.Theme="{StaticResource Theme}" 337.                         Text="{Binding Body, Mode=TwoWay}" 338.                         AcceptsReturn="true" 339.                         Margin="10,10,20,2" 340.                         HorizontalScrollBarVisibility="Auto" 341.                         VerticalScrollBarVisibility="Auto" /> 342.                <!-- Start/End date --> 343.                <TextBlock x:Name="StartDateLabel" 344.                           Grid.Row="2" 345.                           Grid.Column="0" 346.                           Margin="0,13,0,2" 347.                           telerik:LocalizationManager.ResourceKey="StartTime" 348.                           Style="{StaticResource FormElementTextBlockStyle}" /> 349.                <telerikScheduler:DateTimePicker x:Name="StartDateTime" 350.                                                 Height="22" 351.                                                 Grid.Row="2" 352.                                                 Grid.Column="1" 353.                                                 HorizontalAlignment="Left" 354.                                                 Margin="10,10,20,2" 355.                                                 Style="{StaticResource FormElementStyle}" 356.                                                 SelectedDateTime="{Binding Start, Mode=TwoWay}" 357.                                                 telerikScheduler:StartEndDatePicker.EndPicker="{Binding ElementName=EndDateTime}" 358.                                                 IsTabStop="False" 359.                                                 IsEnabled="False" /> 360.                <TextBlock x:Name="EndDateLabel" 361.                           Grid.Row="3" 362.                           Grid.Column="0" 363.                           Margin="0,13,0,2" 364.                           telerik:LocalizationManager.ResourceKey="EndTime" 365.                           Style="{StaticResource FormElementTextBlockStyle}" /> 366.                <telerikScheduler:DateTimePicker x:Name="EndDateTime" 367.                                                 Height="22" 368.                                                 Grid.Row="3" 369.                                                 Grid.Column="1" 370.                                                 HorizontalAlignment="Left" 371.                                                 Margin="10,10,20,2" 372.                                                 Style="{StaticResource FormElementStyle}" 373.                                                 IsTabStop="False" 374.                                                 IsEnabled="False" 375.                                                 SelectedDateTime="{Binding End, Mode=TwoWay}" /> 376.                <!-- Is-all-day selector --> 377.                <CheckBox x:Name="AllDayEventCheckbox" 378.                          IsChecked="{Binding IsAllDayEvent, Mode=TwoWay}" 379.                          Grid.Row="4" 380.                          Grid.Column="1" 381.                          Margin="10,10,20,2" 382.                          HorizontalAlignment="Left" 383.                          telerik:StyleManager.Theme="{StaticResource Theme}" 384.                          telerik:LocalizationManager.ResourceKey="AllDayEvent"> 385.                    <telerik:CommandManager.InputBindings> 386.                        <telerik:InputBindingCollection> 387.                            <telerik:MouseBinding Command="telerikScheduler:RadSchedulerCommands.ChangeTimePickersVisibility" 388.                                                  Gesture="LeftClick" /> 389.                        </telerik:InputBindingCollection> 390.                    </telerik:CommandManager.InputBindings> 391.                </CheckBox> 392.                <Grid Grid.Row="5" 393.                      Grid.ColumnSpan="2"> 394.                    <Grid.ColumnDefinitions> 395.                        <ColumnDefinition Width="Auto" 396.                                          MinWidth="100" /> 397.                        <ColumnDefinition Width="Auto" 398.                                          MinWidth="200" /> 399.                    </Grid.ColumnDefinitions> 400.                    <Grid.RowDefinitions> 401.                        <RowDefinition Height="Auto" /> 402.                        <RowDefinition Height="Auto" /> 403.                    </Grid.RowDefinitions> 404.                    <TextBlock Text="Applicant" 405.                               Margin="0,13,0,2" 406.                               Style="{StaticResource FormElementTextBlockStyle}" /> 407.                    <telerikInput:RadComboBox IsEditable="False" 408.                                              Grid.Column="1" 409.                                              Height="24" 410.                                              VerticalAlignment="Center" 411.                                              ItemsSource="{Binding Source={StaticResource DataContextProxy}, Path=DataSource.ApplicantList}" 412.                                              SelectedValue="{Binding ApplicantID, Mode=TwoWay}" 413.                                              SelectedValuePath="ApplicantID" 414.                                              DisplayMemberPath="FirstName" /> 415.                       416.                    <TextBlock Text="Job" 417.                               Margin="0,13,0,2" 418.                               Grid.Row="1" 419.                               Style="{StaticResource FormElementTextBlockStyle}" /> 420.                    <telerikInput:RadComboBox IsEditable="False" 421.                                              Grid.Column="1" 422.                                              Grid.Row="1" 423.                                              Height="24" 424.                                              VerticalAlignment="Center" 425.                                              ItemsSource="{Binding Source={StaticResource DataContextProxy}, Path=DataSource.JobsList}" 426.                                              SelectedValue="{Binding PostingID, Mode=TwoWay}" 427.                                              SelectedValuePath="PostingID" 428.                                              DisplayMemberPath="JobTitle"/> 429.                </Grid> 430.                    <!-- Resources --> 431.                <Grid x:Name="ResourcesLayout" 432.                      Grid.Row="7" 433.                      Grid.Column="0" 434.                      Grid.ColumnSpan="2" 435.                      MaxHeight="130" 436.                      Margin="20,5,20,0"> 437.                    <Border Margin="0" 438.                            BorderThickness="1" 439.                            BorderBrush="{StaticResource GenericShallowBorderBrush}" 440.                            Visibility="{Binding ElementName=ResourcesScrollViewer, Path=ComputedVerticalScrollBarVisibility}"></Border> 441.                    <ScrollViewer x:Name="ResourcesScrollViewer" 442.                                  IsTabStop="false" 443.                                  Grid.Row="6" 444.                                  Grid.Column="0" 445.                                  Grid.ColumnSpan="2" 446.                                  Margin="1" 447.                                  telerik:StyleManager.Theme="{StaticResource Theme}" 448.                                  VerticalScrollBarVisibility="Auto"> 449.                        <scheduler:ResourcesItemsControl x:Name="PART_Resources" 450.                                                         HorizontalAlignment="Left" 451.                                                         Padding="0,2,0,5" 452.                                                         IsTabStop="false" 453.                                                         ItemsSource="{TemplateBinding ResourceTypeModels}" 454.                                                         ItemTemplateSelector="{StaticResource ItemTemplateSelector}" /> 455.                    </ScrollViewer> 456.                </Grid> 457.                <StackPanel x:Name="FooterControls" 458.                            Margin="5 10 10 10" 459.                            Grid.Row="8" 460.                            Grid.Column="1" 461.                            HorizontalAlignment="Left" 462.                            Orientation="Horizontal"> 463.                    <telerik:RadButton x:Name="OKButton" 464.                                       Margin="5" 465.                                       Padding="10 0" 466.                                       MinWidth="80" 467.                                       Command="telerikScheduler:RadSchedulerCommands.SaveAppointment" 468.                                       telerik:StyleManager.Theme="{StaticResource Theme}" 469.                                       telerikNavigation:RadWindow.ResponseButton="Accept" 470.                                       telerik:LocalizationManager.ResourceKey="SaveAndCloseCommandText"> 471.                    </telerik:RadButton> 472.                    <telerik:RadButton x:Name="CancelButton" 473.                                       Margin="5" 474.                                       Padding="10 0" 475.                                       MinWidth="80" 476.                                       telerik:LocalizationManager.ResourceKey="Cancel" 477.                                       telerik:StyleManager.Theme="{StaticResource Theme}" 478.                                       telerikNavigation:RadWindow.ResponseButton="Cancel" 479.                                       Command="telerik:WindowCommands.Close"> 480.                    </telerik:RadButton> 481.                </StackPanel> 482.            </Grid> 483.            <vsm:VisualStateManager.VisualStateGroups> 484.                <vsm:VisualStateGroup x:Name="RecurrenceRuleState"> 485.                    <vsm:VisualState x:Name="RecurrenceRuleIsNull"> 486.                        <Storyboard> 487.                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="StartDateTime" 488.                                                           Storyboard.TargetProperty="IsEnabled" 489.                                                           Duration="0"> 490.                                <DiscreteObjectKeyFrame KeyTime="0" 491.                                                        Value="True" /> 492.                            </ObjectAnimationUsingKeyFrames> 493.                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="EndDateTime" 494.                                                           Storyboard.TargetProperty="IsEnabled" 495.                                                           Duration="0"> 496.                                <DiscreteObjectKeyFrame KeyTime="0" 497.                                                        Value="True" /> 498.                            </ObjectAnimationUsingKeyFrames> 499.                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="AllDayEventCheckbox" 500.                                                           Storyboard.TargetProperty="IsEnabled" 501.                                                           Duration="0"> 502.                                <DiscreteObjectKeyFrame KeyTime="0" 503.                                                        Value="True" /> 504.                            </ObjectAnimationUsingKeyFrames> 505.                        </Storyboard> 506.                    </vsm:VisualState> 507.                    <vsm:VisualState x:Name="RecurrenceRuleIsNotNull"> 508.                        <Storyboard> 509.                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="StartDateTime" 510.                                                           Storyboard.TargetProperty="IsEnabled" 511.                                                           Duration="0"> 512.                                <DiscreteObjectKeyFrame KeyTime="0" 513.                                                        Value="False" /> 514.                            </ObjectAnimationUsingKeyFrames> 515.                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="EndDateTime" 516.                                                           Storyboard.TargetProperty="IsEnabled" 517.                                                           Duration="0"> 518.                                <DiscreteObjectKeyFrame KeyTime="0" 519.                                                        Value="False" /> 520.                            </ObjectAnimationUsingKeyFrames> 521.                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="AllDayEventCheckbox" 522.                                                           Storyboard.TargetProperty="IsEnabled" 523.                                                           Duration="0"> 524.                                <DiscreteObjectKeyFrame KeyTime="0" 525.                                                        Value="False" /> 526.                            </ObjectAnimationUsingKeyFrames> 527.                        </Storyboard> 528.                    </vsm:VisualState> 529.                </vsm:VisualStateGroup> 530.            </vsm:VisualStateManager.VisualStateGroups> 531.        </StackPanel> 532.    </ControlTemplate> 533.    <DataTemplate x:Key="AppointmentDialogWindowHeaderDataTemplate"> 534.        <StackPanel Orientation="Horizontal" 535.                    MaxWidth="400"> 536.            <TextBlock telerik:LocalizationManager.ResourceKey="Event" 537.                       Visibility="{Binding Appointment.IsAllDayEvent, Converter={StaticResource BooleanToVisibilityConverter}}" /> 538.            <TextBlock telerik:LocalizationManager.ResourceKey="Appointment" 539.                       Visibility="{Binding Appointment.IsAllDayEvent, Converter={StaticResource InvertedBooleanToVisibilityConverter}}" /> 540.            <TextBlock Text=" - " /> 541.            <TextBlock x:Name="SubjectTextBlock" 542.                       Visibility="{Binding Appointment.Subject, Converter={StaticResource NullToVisibilityConverter}}" 543.                       Text="{Binding Appointment.Subject}" /> 544.            <TextBlock telerik:LocalizationManager.ResourceKey="Untitled" 545.                       Visibility="{Binding Appointment.Subject, Converter={StaticResource InvertedNullToVisibilityConverter}}" /> 546.        </StackPanel> 547.    </DataTemplate> 548.    <Style x:Key="EditAppointmentStyle" 549.           TargetType="telerikScheduler:AppointmentDialogWindow"> 550.        <Setter Property="IconTemplate" 551.                Value="{StaticResource IconDataEditTemplate}" /> 552.        <Setter Property="HeaderTemplate" 553.                Value="{StaticResource AppointmentDialogWindowHeaderDataTemplate}" /> 554.        <Setter Property="Background" 555.                Value="{StaticResource DialogWindowBackground}" /> 556.        <Setter Property="Template" 557.                Value="{StaticResource EditAppointmentTemplate}" /> 558.    </Style> 559.</UserControl.Resources> The first line there is the DataContextProxy I mentioned previously- we use that again to work a bit of magic in this template. Where we start getting into the dialog in question is line 132, but line 407 is where things start getting interesting.  The ItemsSource is pointing at a list that exists in my ViewModel (or code-behind, if it is used as a DataContext), the SelectedValue is the item I am actually binding from the applicant (note the TwoWay binding), and SelectedValuePath and DisplayMemberPath ensure the proper applicant is being displayed from the collection.  You will also see similar starting on line 420 where I do the same for the Jobs we'll be displaying. Just to wrap-up the Xaml, here's the RadScheduler declaraction that ties this all together and will be the main focus of our view: 01.<telerikScheduler:RadScheduler x:Name="xJobsScheduler" 02.                  Grid.Row="1" 03.                  Grid.Column="1" 04.                  Width="800" 05.                  MinWidth="600" 06.                  Height="500" 07.                  MinHeight="300" 08.                  AppointmentsSource="{Binding Interviews}" 09.                  EditAppointmentStyle="{StaticResource EditAppointmentStyle}" 10.                  command:AppointmentAddedEventClass.Command="{Binding AddAppointmentCommand}" 11.                  command:ApptCreatedEventClass.Command="{Binding ApptCreatingCommand}" 12.                  command:ApptEditedEventClass.Command="{Binding ApptEditedCommand}" 13.                  command:ApptDeletedEventClass.Command="{Binding ApptDeletedCommand}"> 14.</telerikScheduler:RadScheduler> Now, we get to the ViewModel and what it takes to get that rigged up.  And for those of you who remember the jobs post, those command:s in the Xaml are pointing to attached behavior commands that reproduce the respective events.  This becomes very handy when we're setting up the code-behind version. ;) ViewModel I've been liking this approach so far, so I'm going to put the entire ViewModel here and then go into the lines of interest.  Of course, feel free to ask me questions about anything that isn't clear (by line number, ideally) so I can help out if I have missed anything important: 001.public class SchedulerViewModel : ViewModelBase 002.{ 003.    private readonly IEventAggregator eventAggregator; 004.    private readonly IRegionManager regionManager; 005.   006.    public RecruitingContext context; 007.   008.    private ObservableItemCollection<InterviewAppointment> _interviews = new ObservableItemCollection<InterviewAppointment>(); 009.    public ObservableItemCollection<InterviewAppointment> Interviews 010.    { 011.        get { return _interviews; } 012.        set 013.        { 014.            if (_interviews != value) 015.            { 016.                _interviews = value; 017.                NotifyChanged("Interviews"); 018.            } 019.        } 020.    } 021.   022.    private QueryableCollectionView _jobsList; 023.    public QueryableCollectionView JobsList 024.    { 025.        get { return this._jobsList; } 026.        set 027.        { 028.            if (this._jobsList != value) 029.            { 030.                this._jobsList = value; 031.                this.NotifyChanged("JobsList"); 032.            } 033.        } 034.    } 035.   036.    private QueryableCollectionView _applicantList; 037.    public QueryableCollectionView ApplicantList 038.    { 039.        get { return _applicantList; } 040.        set 041.        { 042.            if (_applicantList != value) 043.            { 044.                _applicantList = value; 045.                NotifyChanged("ApplicantList"); 046.            } 047.        } 048.    } 049.   050.    public DelegateCommand<object> AddAppointmentCommand { get; set; } 051.    public DelegateCommand<object> ApptCreatingCommand { get; set; } 052.    public DelegateCommand<object> ApptEditedCommand { get; set; } 053.    public DelegateCommand<object> ApptDeletedCommand { get; set; } 054.   055.    public SchedulerViewModel(IEventAggregator eventAgg, IRegionManager regionmanager) 056.    { 057.        // set Unity items 058.        this.eventAggregator = eventAgg; 059.        this.regionManager = regionmanager; 060.   061.        // load our context 062.        context = new RecruitingContext(); 063.        LoadOperation<Interview> loadOp = context.Load(context.GetInterviewsQuery()); 064.        loadOp.Completed += new EventHandler(loadOp_Completed); 065.   066.        this._jobsList = new QueryableCollectionView(context.JobPostings); 067.        context.Load(context.GetJobPostingsQuery()); 068.   069.        this._applicantList = new QueryableCollectionView(context.Applicants); 070.        context.Load(context.GetApplicantsQuery()); 071.   072.        AddAppointmentCommand = new DelegateCommand<object>(this.AddAppt); 073.        ApptCreatingCommand = new DelegateCommand<object>(this.ApptCreating); 074.        ApptEditedCommand = new DelegateCommand<object>(this.ApptEdited); 075.        ApptDeletedCommand = new DelegateCommand<object>(this.ApptDeleted); 076.   077.    } 078.   079.    void loadOp_Completed(object sender, EventArgs e) 080.    { 081.        LoadOperation loadop = sender as LoadOperation; 082.   083.        foreach (var ent in loadop.Entities) 084.        { 085.            _interviews.Add(EntityToAppointment(ent as Interview)); 086.        } 087.    } 088.   089.    #region Appointment Adding 090.   091.    public void AddAppt(object obj) 092.    { 093.        // now we have a new InterviewAppointment to add to our QCV :) 094.        InterviewAppointment newInterview = obj as InterviewAppointment; 095.   096.        this.context.Interviews.Add(AppointmentToEntity(newInterview)); 097.        this.context.SubmitChanges((s) => 098.        { 099.            ActionHistory myAction = new ActionHistory(); 100.            myAction.InterviewID = newInterview.InterviewID; 101.            myAction.PostingID = newInterview.PostingID; 102.            myAction.ApplicantID = newInterview.ApplicantID; 103.            myAction.Description = String.Format("Interview with {0} has been created by {1}", newInterview.ApplicantID.ToString(), "default user"); 104.            myAction.TimeStamp = DateTime.Now; 105.            eventAggregator.GetEvent<AddActionEvent>().Publish(myAction); 106.        } 107.            , null); 108.    } 109.   110.    public void ApptCreating(object obj) 111.    { 112.        // handled in the behavior, just a placeholder to ensure it runs :) 113.    } 114.   115.    #endregion 116.   117.    #region Appointment Editing 118.   119.    public void ApptEdited(object obj) 120.    { 121.        Interview editedInterview = (from x in context.Interviews 122.                            where x.InterviewID == (obj as InterviewAppointment).InterviewID 123.                            select x).SingleOrDefault(); 124.   125.        CopyAppointmentEdit(editedInterview, obj as InterviewAppointment); 126.   127.        context.SubmitChanges((s) => { 128.            ActionHistory myAction = new ActionHistory(); 129.            myAction.InterviewID = editedInterview.InterviewID; 130.            myAction.PostingID = editedInterview.PostingID; 131.            myAction.ApplicantID = editedInterview.ApplicantID; 132.            myAction.Description = String.Format("Interview with {0} has been modified by {1}", editedInterview.ApplicantID.ToString(), "default user"); 133.            myAction.TimeStamp = DateTime.Now; 134.            eventAggregator.GetEvent<AddActionEvent>().Publish(myAction); } 135.            , null); 136.    } 137.   138.    #endregion 139.   140.    #region Appointment Deleting 141.   142.    public void ApptDeleted(object obj) 143.    { 144.        Interview deletedInterview = (from x in context.Interviews 145.                                      where x.InterviewID == (obj as InterviewAppointment).InterviewID 146.                                      select x).SingleOrDefault(); 147.   148.        context.Interviews.Remove(deletedInterview); 149.        context.SubmitChanges((s) => 150.        { 151.            ActionHistory myAction = new ActionHistory(); 152.            myAction.InterviewID = deletedInterview.InterviewID; 153.            myAction.PostingID = deletedInterview.PostingID; 154.            myAction.ApplicantID = deletedInterview.ApplicantID; 155.            myAction.Description = String.Format("Interview with {0} has been deleted by {1}", deletedInterview.ApplicantID.ToString(), "default user"); 156.            myAction.TimeStamp = DateTime.Now; 157.            eventAggregator.GetEvent<AddActionEvent>().Publish(myAction); 158.        } 159.            , null); 160.    } 161.   162.    #endregion 163.   164.    #region Appointment Helpers :) 165.   166.    public Interview AppointmentToEntity(InterviewAppointment ia) 167.    { 168.        Interview newInterview = new Interview(); 169.        newInterview.Subject = ia.Subject; 170.        newInterview.Body = ia.Body; 171.        newInterview.Start = ia.Start; 172.        newInterview.End = ia.End; 173.        newInterview.ApplicantID = ia.ApplicantID; 174.        newInterview.PostingID = ia.PostingID; 175.        newInterview.InterviewID = ia.InterviewID; 176.   177.        return newInterview; 178.    } 179.   180.    public InterviewAppointment EntityToAppointment(Interview ia) 181.    { 182.        InterviewAppointment newInterview = new InterviewAppointment(); 183.        newInterview.Subject = ia.Subject; 184.        newInterview.Body = ia.Body; 185.        newInterview.Start = ia.Start; 186.        newInterview.End = ia.End; 187.        newInterview.ApplicantID = ia.ApplicantID; 188.        newInterview.PostingID = ia.PostingID; 189.        newInterview.InterviewID = ia.InterviewID; 190.   191.        return newInterview; 192.    } 193.   194.    public void CopyAppointmentEdit(Interview entityInterview, InterviewAppointment appointmentInterview) 195.    { 196.        entityInterview.Subject = appointmentInterview.Subject; 197.        entityInterview.Body = appointmentInterview.Body; 198.        entityInterview.Start = appointmentInterview.Start; 199.        entityInterview.End = appointmentInterview.End; 200.        entityInterview.ApplicantID = appointmentInterview.ApplicantID; 201.        entityInterview.PostingID = appointmentInterview.PostingID; 202.    } 203.   204.    #endregion 205.} One thing we're doing here which you won't see in any of the other ViewModels is creating a duplicate collection.  I know this is something which will be fixed down the line for using RadScheduler, simplifying this process, but with WCF RIA changing as it does I wanted to ensure functionality would remain consistent as I continued development on this application.  So, I do a little bit of duplication, but for the greater good.  This all takes place starting on line 79, so for every entity that comes back we add it to the collection that is bound to RadScheduler.  Otherwise, the DelegateCommands that you see correspond directly to the events they are named after.  In each case, rather than sending over the full event arguments, I just send in the appointment in question (coming through as the object obj in all cases) so I can add (line 91), edit (line 119), and delete appointments (line 142) like normal.  This just ensures they get updated back to my database.  Also, the one bit of code you won't see is for the Appointment Creating (line 110) event- that is because in the command I've created I simply make the replacement I need to: 1.void element_AppointmentCreating(object sender, AppointmentCreatingEventArgs e) 2.{ 3.    e.NewAppointment = new InterviewAppointment(); 4.    base.ExecuteCommand(); 5.} And the ViewModel is none the wiser, the appointments just work as far as it is concerned since as they are created they become InterviewAppointments.  End result?  I've customized my EditAppointmentDialog as follows: And adding, editing, and deleting appointments works like a charm.  I can even 'edit' by moving appointments around RadScheduler, so as they are dropped into a timeslot they perform their full edit routine and things get updated. And then, the Code-Behind Version Perhaps the thing I like the most about doing one then the other is I get to steal 90% or more of the code from the MVVM version.  For example, the only real changes to the Code-Behind Xaml file exist in the control declaration, in which I use events instead of attached-behavior-event-commands: 01.<telerikScheduler:RadScheduler x:Name="xJobsScheduler" 02.                  Grid.Row="1" 03.                  Grid.Column="1" 04.                  Width="800" 05.                  MinWidth="600" 06.                  Height="500" 07.                  MinHeight="300" 08.                  EditAppointmentStyle="{StaticResource EditAppointmentStyle}" 09.                  AppointmentAdded="xJobsScheduler_AppointmentAdded" 10.                  AppointmentCreating="xJobsScheduler_AppointmentCreating" 11.                  AppointmentEdited="xJobsScheduler_AppointmentEdited" 12.                  AppointmentDeleted="xJobsScheduler_AppointmentDeleted"> 13.</telerikScheduler:RadScheduler> Easy, right?  Otherwise, all the same styling in UserControl.Resources was re-used, right down to the DataContextProxy that lets us bind to a collection from our viewmodel (in this case, our code-behind) to use within the DataTemplate.  The code conversion gets even easier, as I could literally copy and paste almost everything from the ViewModel to my Code-Behind, just a matter of pasting the right section into the right event.  Here's the code-behind as proof: 001.public partial class SchedulingView : UserControl, INotifyPropertyChanged 002.{ 003.    public RecruitingContext context; 004.   005.    private QueryableCollectionView _jobsList; 006.    public QueryableCollectionView JobsList 007.    { 008.        get { return this._jobsList; } 009.        set 010.        { 011.            if (this._jobsList != value) 012.            { 013.                this._jobsList = value; 014.                this.NotifyChanged("JobsList"); 015.            } 016.        } 017.    } 018.   019.    private QueryableCollectionView _applicantList; 020.    public QueryableCollectionView ApplicantList 021.    { 022.        get { return _applicantList; } 023.        set 024.        { 025.            if (_applicantList != value) 026.            { 027.                _applicantList = value; 028.                NotifyChanged("ApplicantList"); 029.            } 030.        } 031.    } 032.   033.    private ObservableItemCollection<InterviewAppointment> _interviews = new ObservableItemCollection<InterviewAppointment>(); 034.    public ObservableItemCollection<InterviewAppointment> Interviews 035.    { 036.        get { return _interviews; } 037.        set 038.        { 039.            if (_interviews != value) 040.            { 041.                _interviews = value; 042.                NotifyChanged("Interviews"); 043.            } 044.        } 045.    } 046.   047.    public SchedulingView() 048.    { 049.        InitializeComponent(); 050.   051.        this.DataContext = this; 052.   053.        this.Loaded += new RoutedEventHandler(SchedulingView_Loaded); 054.    } 055.   056.    void SchedulingView_Loaded(object sender, RoutedEventArgs e) 057.    { 058.        this.xJobsScheduler.AppointmentsSource = Interviews; 059.   060.        context = new RecruitingContext(); 061.           062.        LoadOperation loadop = context.Load(context.GetInterviewsQuery()); 063.        loadop.Completed += new EventHandler(loadop_Completed); 064.   065.        this._applicantList = new QueryableCollectionView(context.Applicants); 066.        context.Load(context.GetApplicantsQuery()); 067.   068.        this._jobsList = new QueryableCollectionView(context.JobPostings); 069.        context.Load(context.GetJobPostingsQuery()); 070.    } 071.   072.    void loadop_Completed(object sender, EventArgs e) 073.    { 074.        LoadOperation loadop = sender as LoadOperation; 075.   076.        _interviews.Clear(); 077.   078.        foreach (var ent in loadop.Entities) 079.        { 080.            _interviews.Add(EntityToAppointment(ent as Interview)); 081.        } 082.    } 083.   084.    private void xJobsScheduler_AppointmentAdded(object sender, Telerik.Windows.Controls.AppointmentAddedEventArgs e) 085.    { 086.        // now we have a new InterviewAppointment to add to our QCV :) 087.        InterviewAppointment newInterview = e.Appointment as InterviewAppointment; 088.   089.        this.context.Interviews.Add(AppointmentToEntity(newInterview)); 090.        this.context.SubmitChanges((s) => 091.        { 092.            ActionHistory myAction = new ActionHistory(); 093.            myAction.InterviewID = newInterview.InterviewID; 094.            myAction.PostingID = newInterview.PostingID; 095.            myAction.ApplicantID = newInterview.ApplicantID; 096.            myAction.Description = String.Format("Interview with {0} has been created by {1}", newInterview.ApplicantID.ToString(), "default user"); 097.            myAction.TimeStamp = DateTime.Now; 098.            context.ActionHistories.Add(myAction); 099.            context.SubmitChanges(); 100.        } 101.            , null); 102.    } 103.   104.    private void xJobsScheduler_AppointmentCreating(object sender, Telerik.Windows.Controls.AppointmentCreatingEventArgs e) 105.    { 106.        e.NewAppointment = new InterviewAppointment(); 107.    } 108.   109.    private void xJobsScheduler_AppointmentEdited(object sender, Telerik.Windows.Controls.AppointmentEditedEventArgs e) 110.    { 111.        Interview editedInterview = (from x in context.Interviews 112.                                     where x.InterviewID == (e.Appointment as InterviewAppointment).InterviewID 113.                                     select x).SingleOrDefault(); 114.   115.        CopyAppointmentEdit(editedInterview, e.Appointment as InterviewAppointment); 116.   117.        context.SubmitChanges((s) => 118.        { 119.            ActionHistory myAction = new ActionHistory(); 120.            myAction.InterviewID = editedInterview.InterviewID; 121.            myAction.PostingID = editedInterview.PostingID; 122.            myAction.ApplicantID = editedInterview.ApplicantID; 123.            myAction.Description = String.Format("Interview with {0} has been modified by {1}", editedInterview.ApplicantID.ToString(), "default user"); 124.            myAction.TimeStamp = DateTime.Now; 125.            context.ActionHistories.Add(myAction); 126.            context.SubmitChanges(); 127.        } 128.            , null); 129.    } 130.   131.    private void xJobsScheduler_AppointmentDeleted(object sender, Telerik.Windows.Controls.AppointmentDeletedEventArgs e) 132.    { 133.        Interview deletedInterview = (from x in context.Interviews 134.                                      where x.InterviewID == (e.Appointment as InterviewAppointment).InterviewID 135.                                      select x).SingleOrDefault(); 136.   137.        context.Interviews.Remove(deletedInterview); 138.        context.SubmitChanges((s) => 139.        { 140.            ActionHistory myAction = new ActionHistory(); 141.            myAction.InterviewID = deletedInterview.InterviewID; 142.            myAction.PostingID = deletedInterview.PostingID; 143.            myAction.ApplicantID = deletedInterview.ApplicantID; 144.            myAction.Description = String.Format("Interview with {0} has been deleted by {1}", deletedInterview.ApplicantID.ToString(), "default user"); 145.            myAction.TimeStamp = DateTime.Now; 146.            context.ActionHistories.Add(myAction); 147.            context.SubmitChanges(); 148.        } 149.            , null); 150.    } 151.   152.    #region Appointment Helpers :) 153.   154.    public Interview AppointmentToEntity(InterviewAppointment ia) 155.    { 156.        Interview newInterview = new Interview(); 157.        newInterview.Subject = ia.Subject; 158.        newInterview.Body = ia.Body; 159.        newInterview.Start = ia.Start; 160.        newInterview.End = ia.End; 161.        newInterview.ApplicantID = ia.ApplicantID; 162.        newInterview.PostingID = ia.PostingID; 163.        newInterview.InterviewID = ia.InterviewID; 164.   165.        return newInterview; 166.    } 167.   168.    public InterviewAppointment EntityToAppointment(Interview ia) 169.    { 170.        InterviewAppointment newInterview = new InterviewAppointment(); 171.        newInterview.Subject = ia.Subject; 172.        newInterview.Body = ia.Body; 173.        newInterview.Start = ia.Start; 174.        newInterview.End = ia.End; 175.        newInterview.ApplicantID = ia.ApplicantID; 176.        newInterview.PostingID = ia.PostingID; 177.        newInterview.InterviewID = ia.InterviewID; 178.   179.        return newInterview; 180.    } 181.   182.    public void CopyAppointmentEdit(Interview entityInterview, InterviewAppointment appointmentInterview) 183.    { 184.        entityInterview.Subject = appointmentInterview.Subject; 185.        entityInterview.Body = appointmentInterview.Body; 186.        entityInterview.Start = appointmentInterview.Start; 187.        entityInterview.End = appointmentInterview.End; 188.        entityInterview.ApplicantID = appointmentInterview.ApplicantID; 189.        entityInterview.PostingID = appointmentInterview.PostingID; 190.    } 191.   192.    #endregion 193.   194.    #region INotifyPropertyChanged Members 195.   196.    public event PropertyChangedEventHandler PropertyChanged; 197.   198.    public void NotifyChanged(string propertyName) 199.    { 200.        if (string.IsNullOrEmpty(propertyName)) 201.            throw new ArgumentException("propertyName"); 202.   203.        PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); 204.    } 205.   206.    #endregion 207.} Nice... right? :) One really important thing to note as well.  See on line 51 where I set the DataContext before the Loaded event?  This is super important, as if you don't have this set before the usercontrol is loaded, the DataContextProxy has no context to use and your EditAppointmentDialog Job/Applicant dropdowns will be blank and empty.  Trust me on this, took a little bit of debugging to figure out that by setting the DataContext post-loaded would only lead to disaster and frustration.  Otherwise, the only other real difference is that instead of sending an ActionHistory item through an event to get added to the database and saved, I do those right in the callback from submitting.  The Result Again, I only have to post one picture because these bad boys used nearly identical code for both the MVVM and the code-behind views, so our end result is... So what have we learned here today?  One, for the most part this MVVM thing is somewhat easy.  Yeah, you sometimes have to write a bunch of extra code, but with the help of a few useful snippits you can turn the process into a pretty streamlined little workflow.  Heck, this story gets even easier as you can see in this blog post by Michael Washington- specifically run a find on 'InvokeCommandAction' and you'll see the section regarding the command on TreeView in Blend 4.  Brilliant!  MVVM never looked so sweet! Otherwise, it is business as usual with RadScheduler for Silverlight whichever path you're choosing for your development.  Between now and the next post, I'll be cleaning up styles a bit (those RadComboBoxes are a little too close to my labels!) and adding some to the RowDetailsViews for Applicants and Jobs, so you can see all the info for an appointment in the dropdown tab view.  Otherwise, we're about ready to call a wrap on this oneDid you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• WPF DatePicker UpdateSourceTrigger PropertyChanged not working...

  - by user557352

  I am using MVVM and want to enable a button on text change of datepicker control.. XAML Code Binding on DatePicker SelectedDate="{Binding InactiveDate, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" DisplayDate="{Binding InactiveDate, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Binding on Button View Model Code I am using a DelegateCommand for button click View Model Delegate Initialization SubmitCommand = new DelegateCommand(OnSubmitRequested, AllowSubmit, Controller); The AllowSubmit implementation private bool AllowSubmit() { return InactiveDate != null; } InactiveDate Property implementation public DateTime? InactiveDate { get { return _inactiveDate; } set { _inactiveDate = value; SubmitCommand.RaiseCanExecuteChanged(); PropertyChanged(this, new PropertyChangedEventArgs("InactiveDate")); } } SubmitCommand.RaiseCanExecuteChanged() should enable the button once I enter any character on DateTimePicker but it is not happening.

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• Binding the property to a control defined inside a listboxitem template

  - by Malcolm

  I have a class called ledgerObject : public class LedgerObject { public ChargeLine ChargeLine{ get; set; } public DelegateCommand Click_hyperbnCommand{ get; private set; } public LedgerObject() { this.Click_hyperbnCommand = new DelegateCommand(click_btn); } private void click_btn(object args) { } } The chargeLine which is the property of this class is itself a class and has some properties in it. So I am binding the datacontext of a listbox to an array of LedgerObject, and I want to bind the textblock control defined inside a listboxitem template to the property of a ChargeLine. Any idea or suggestion will help. I have tried this but not working: <TextBlock Margin="4 0 4 0" Grid.Column="3" Text="{Binding Path=ChargeLine.SimCode}" TextDecorations="Underline" Foreground="Red" />

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• What is the accepted pattern for WPF commanding in MVVM?

  - by Robert S.

  I'm working on a WPF app and I understand the command pattern pretty well, but I've found that there are several different implementations of the command pattern for MVVM. There's Josh Smith's implementation in his WPF sample app, the DelegateCommand from Prism, and the CommandBindings implementation. My question is, what is the generally accepted best practice for using commands with MVVM? My application uses Prism so DelegateCommand is available to us. The devs on my team are arguing about which approach is "best." Some don't like the numerous .cs files generated for each command, others prefer that everything be wired up via CommandBindings. I'm at a loss. Can anyone shed some light?

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• Enable button based on TextBox value (WPF)

  - by zendar

  This is MVVM application. There is a window and related view model class. There is TextBox, Button and ListBox on form. Button is bound to DelegateCommand that has CanExecute function. Idea is that user enters some data in text box, presses button and data is appended to list box. I would like to enable command (and button) when user enters correct data in TextBox. Things work like this now: CanExecute() method contains code that checks if data in property bound to text box is correct. Text box is bound to property in view model UpdateSourceTrigger is set to PropertyChanged and property in view model is updated after each key user presses. Problem is that CanExecute() does not fire when user enters data in text box. It doesn't fire even when text box lose focus. How could I make this work? Edit: Re Yanko's comment: Delegate command is implemented in MVVM toolkit template and when you create new MVVM project, there is Delegate command in solution. As much as I saw in Prism videos this should be the same class (or at least very similar). Here is XAML snippet: ... <UserControl.Resources> <views:CommandReference x:Key="AddObjectCommandReference" Command="{Binding AddObjectCommand}" /> </UserControl.Resources> ... <TextBox Text="{Binding ObjectName, UpdateSourceTrigger=PropertyChanged}"> </TextBox> <Button Command="{StaticResource AddObjectCommandReference}">Add</Button> ... View model: // Property bound to textbox public string ObjectName { get { return objectName; } set { objectName = value; OnPropertyChanged("ObjectName"); } } // Command bound to button public ICommand AddObjectCommand { get { if (addObjectCommand == null) { addObjectCommand = new DelegateCommand(AddObject, CanAddObject); } return addObjectCommand; } } private void AddObject() { if (ObjectName == null || ObjectName.Length == 0) return; objectNames.AddSourceFile(ObjectName); OnPropertyChanged("ObjectNames"); // refresh listbox } private bool CanAddObject() { return ObjectName != null && ObjectName.Length > 0; } As I wrote in the first part of question, following things work: property setter for ObjectName is triggered on every keypress in textbox if I put return true; in CanAddObject(), command is active (button to) It looks to me that binding is correct. Thing that I don't know is how to make CanExecute() fire in setter of ObjectName property from above code. Re Ben's and Abe's answers: CanExecuteChanged() is event handler and compiler complains: The event 'System.Windows.Input.ICommand.CanExecuteChanged' can only appear on the left hand side of += or -= there are only two more members of ICommand: Execute() and CanExecute() Do you have some example that shows how can I make command call CanExecute(). I found command manager helper class in DelegateCommand.cs and I'll look into it, maybe there is some mechanism that could help. Anyway, idea that in order to activate command based on user input, one needs to "nudge" command object in property setter code looks clumsy. It will introduce dependencies and one of big points of MVVM is reducing them. Is it possible to solve this problem by using dependency properties?

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• Can I remove duplicating events in EventAggregator?

  - by Mcad001

  Hi, I have a quite simple scenario that I cannot get to work correctly. I have 2 views, CarView and CarWindowView (childwindow) with corresponding ViewModels. In my CarView I have an EditButton that that opens CarWindowView (childwindow) where I can edit the Car object fields. My problem is that the DisplayModule method in my CarWindowView ViewModel is getting called too many times...When I push the edit button first time its getting called once, the second time its getting called twince, the third time its getting called 3 times and so fort... ! CarView ViewModel constructor: Public Sub New(ByVal eventAggregator As IEventAggregator, ByVal con As IUnityContainer, ByVal mgr As ICarManager, ByVal CarService As ICarService) _Container = con _CarManager = mgr _EventAggregator = eventAggregator 'Create the DelegateCommands NewBtnClick = New DelegateCommand(Of Object)(AddressOf HandleNewCarBtnClick) EditBtnClick = New DelegateCommand(Of Object)(AddressOf HandleEditCarBtnClick) End Sub CarView ViewModel HandleEditCarBtnClick method: Private Sub HandleEditCarBtnClick() Dim view = New CarWindowView Dim viewModel = _Container.Resolve(Of CarWindowViewModel)() viewModel.CurrentDomainContext = DomainContext viewModel.CurrentItem = CurrentItem viewModel.IsEnabled = False view.ApplyModel(viewModel) view.Show() _EventAggregator.GetEvent(Of CarCollectionEvent)().Publish(EditObject) End Sub CarWindowView ViewModel constructor: Public Sub New(ByVal eventAggregator As IEventAggregator, ByVal con As IUnityContainer, ByVal mgr As ICarManager, ByVal CarService As ICarService) _Container = con _CarManager = mgr _EventAggregator = eventAggregator _EventAggregator.GetEvent(Of CarCollectionEvent).Subscribe(AddressOf DisplayModule) End Sub CarWindowView ViewModel DisplayModule method (this is the method getting called too many times): Public Sub DisplayModule(ByVal param As String) If param = EditObject Then IsInEditMode = True ' Logic removed for display reasons here. This logic breaks because it's called too many times. End If End Sub So, I cannot understand how I can only have the EventAggregator to store just the one single click, and not all my click on the Edit button. Sorry if this is not to well explained! Help appreciated!!

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• Refreshing Read-Only (Chained) Property in MVVM

  - by Wonko the Sane

  I'm thinking this should be easy, but I can't seem to figure this out. Take these properties from an example ViewModel (ObservableViewModel implements INotifyPropertyChanged): class NameViewModel : ObservableViewModel { Boolean mShowFullName = false; string mFirstName = "Wonko"; string mLastName = "DeSane"; private readonly DelegateCommand mToggleName; public NameViewModel() { mToggleName = new DelegateCommand(() => ShowFullName = !mShowFullName); } public ICommand ToggleNameCommand { get { return mToggleName; } } public Boolean ShowFullName { get { return mShowFullName; } set { SetPropertyValue("ShowFullName", ref mShowFullName, value); } } public string Name { get { return (mShowFullName ? this.FullName : this.Initials); } } public string FullName { get { return mFirstName + " " + mLastName; } } public string Initials { get { return mFirstName.Substring(0, 1) + "." + mLastName.Substring(0, 1) + "."; } } } The guts of such a [insert your adjective here] View using this ViewModel might look like: <TextBlock x:Name="txtName" Grid.Row="0" Text="{Binding Name}" /> <Button x:Name="btnToggleName" Command="{Binding ToggleNameCommand}" Content="Toggle Name" Grid.Row="1" /> The problem I am seeing is when the ToggleNameCommand is fired. The ShowFullName property is properly updated by the command, but the Name binding is never updated in the View. What am I missing? How can I force the binding to update? Do I need to implement the Name properties as DependencyProperties (and therefore derive from DependencyObject)? Seems a little heavyweight to me, and I'm hoping for a simpler solution. Thanks, wTs

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• Open File Dialog MVVM

  - by Jose

  Ok I really would like to know how expert MVVM developers handle an openfile dialog in WPF. I don't really want to do this in my ViewModel(where 'Browse' is referenced via a DelegateCommand) void Browse(object param) { //Add code here OpenFileDialog d = new OpenFileDialog(); if (d.ShowDialog() == true) { //Do stuff } } Because I believe that goes against MVVM methodology. What do I do?

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• CheckBox Command Behaviors for Silverlight MVVM Pattern

  - by Blake Blackwell

  I am trying to detect when an item is checked, and which item is checked in a ListBox using Silverlight 4 and the Prism framework. I found this example on creating behaviors, and tried to follow it but nothing is happening in the debugger. I have three questions: Why isn't my command executing? How do I determine which item was checked (i.e. pass a command parameter)? How do I debug this? (i.e. where can I put break points to begin stepping into this) Here is my code: View: <ListBox x:Name="MyListBox" ItemsSource="{Binding PanelItems, Mode=TwoWay}"> <ListBox.ItemTemplate> <DataTemplate> <StackPanel Orientation="Horizontal"> <CheckBox IsChecked="{Binding Enabled}" my:Checked.Command="{Binding Check}" /> <TextBlock x:Name="DisplayName" Text="{Binding DisplayName}"/> </StackPanel> </DataTemplate> </ListBox.ItemTemplate> </ListBox> ViewModel: public MainPageViewModel() { _panelItems.Add( new PanelItem { Enabled = true, DisplayName = "Test1" } ); Check = new DelegateCommand<object>( itemChecked ); } public void itemChecked( object o ) { //do some stuff } public DelegateCommand<object> Check { get; set; } Behavior Class public class CheckedBehavior : CommandBehaviorBase<CheckBox> { public CheckedBehavior( CheckBox element ) : base( element ) { element.Checked +=new RoutedEventHandler(element_Checked); } void element_Checked( object sender, RoutedEventArgs e ) { base.ExecuteCommand(); } } Command Class public static class Checked { public static ICommand GetCommand( DependencyObject obj ) { return (ICommand) obj.GetValue( CommandProperty ); } public static void SetCommand( DependencyObject obj, ICommand value ) { obj.SetValue( CommandProperty, value ); } public static readonly DependencyProperty CommandProperty = DependencyProperty.RegisterAttached( "Command", typeof( CheckBox ), typeof( Checked ), new PropertyMetadata( OnSetCommandCallback ) ); public static readonly DependencyProperty CheckedCommandBehaviorProperty = DependencyProperty.RegisterAttached( "CheckedCommandBehavior", typeof( CheckedBehavior ), typeof( Checked ), null ); private static void OnSetCommandCallback( DependencyObject dependencyObject, DependencyPropertyChangedEventArgs e ) { CheckBox element = dependencyObject as CheckBox; if( element != null ) { CheckedBehavior behavior = GetOrCreateBehavior( element ); behavior.Command = e.NewValue as ICommand; } } private static CheckedBehavior GetOrCreateBehavior( CheckBox element ) { CheckedBehavior behavior = element.GetValue( CheckedCommandBehaviorProperty ) as CheckedBehavior; if( behavior == null ) { behavior = new CheckedBehavior( element ); element.SetValue( CheckedCommandBehaviorProperty, behavior ); } return behavior; } public static CheckedBehavior GetCheckCommandBehavior( DependencyObject obj ) { return (CheckedBehavior) obj.GetValue( CheckedCommandBehaviorProperty ); } public static void SetCheckCommandBehavior( DependencyObject obj, CheckedBehavior value ) { obj.SetValue( CheckedCommandBehaviorProperty, value ); } } I used this article to get me started, but I'll readily admit this is over my head.

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• Building applications with WPF, MVVM and Prism(aka CAG)

  - by skjagini

  In this article I am going to walk through an application using WPF and Prism (aka composite application guidance, CAG) which simulates engaging a taxi (cab).  The rules are simple, the app would have3 screens A login screen to authenticate the user An information screen. A screen to engage the cab and roam around and calculating the total fare Metered Rate of Fare The meter is required to be engaged when a cab is occupied by anyone $3.00 upon entry $0.35 for each additional unit The unit fare is: one-fifth of a mile, when the cab is traveling at 6 miles an hour or more; or 60 seconds when not in motion or traveling at less than 12 miles per hour. Night surcharge of $.50 after 8:00 PM & before 6:00 AM Peak hour Weekday Surcharge of $1.00 Monday - Friday after 4:00 PM & before 8:00 PM New York State Tax Surcharge of $.50 per ride. Example: Friday (2010-10-08) 5:30pm Start at Lexington Ave & E 57th St End at Irving Pl & E 15th St Start = $3.00 Travels 2 miles at less than 6 mph for 15 minutes = $3.50 Travels at more than 12 mph for 5 minutes = $1.75 Peak hour Weekday Surcharge = $1.00 (ride started at 5:30 pm) New York State Tax Surcharge = $0.50 Before we dive into the app, I would like to give brief description about the framework.  If you want to jump on to the source code, scroll all the way to the end of the post. MVVM MVVM pattern is in no way related to the usage of PRISM in your application and should be considered if you are using WPF irrespective of PRISM or not. Lets say you are not familiar with MVVM, your typical UI would involve adding some UI controls like text boxes, a button, double clicking on the button,  generating event handler, calling a method from business layer and updating the user interface, it works most of the time for developing small scale applications. The problem with this approach is that there is some amount of code specific to business logic wrapped in UI specific code which is hard to unit test it, mock it and MVVM helps to solve the exact problem. MVVM stands for Model(M) – View(V) – ViewModel(VM),  based on the interactions with in the three parties it should be called VVMM,  MVVM sounds more like MVC (Model-View-Controller) so the name. Why it should be called VVMM: View – View Model - Model WPF allows to create user interfaces using XAML and MVVM takes it to the next level by allowing complete separation of user interface and business logic. In WPF each view will have a property, DataContext when set to an instance of a class (which happens to be your view model) provides the data the view is interested in, i.e., view interacts with view model and at the same time view model interacts with view through DataContext. Sujith, if view and view model are interacting directly with each other how does MVVM is helping me separation of concerns? Well, the catch is DataContext is of type Object, since it is of type object view doesn’t know exact type of view model allowing views and views models to be loosely coupled. View models aggregate data from models (data access layer, services, etc) and make it available for views through properties, methods etc, i.e., View Models interact with Models. PRISM Prism is provided by Microsoft Patterns and Practices team and it can be downloaded from codeplex for source code,  samples and documentation on msdn.  The name composite implies, to compose user interface from different modules (views) without direct dependencies on each other, again allowing  loosely coupled development. Well Sujith, I can already do that with user controls, why shall I learn another framework?  That’s correct, you can decouple using user controls, but you still have to manage some amount of coupling, like how to do you communicate between the controls, how do you subscribe/unsubscribe, loading/unloading views dynamically. Prism is not a replacement for user controls, provides the following features which greatly help in designing the composite applications. Dependency Injection (DI)/ Inversion of Control (IoC) Modules Regions Event Aggregator  Commands Simply put, MVVM helps building a single view and Prism helps building an application using the views There are other open source alternatives to Prism, like MVVMLight, Cinch, take a look at them as well. Lets dig into the source code.  1. Solution The solution is made of the following projects Framework: Holds the common functionality in building applications using WPF and Prism TaxiClient: Start up project, boot strapping and app styling TaxiCommon: Helps with the business logic TaxiModules: Holds the meat of the application with views and view models TaxiTests: To test the application 2. DI / IoC Dependency Injection (DI) as the name implies refers to injecting dependencies and Inversion of Control (IoC) means the calling code has no direct control on the dependencies, opposite of normal way of programming where dependencies are passed by caller, i.e inversion; aside from some differences in terminology the concept is same in both the cases. The idea behind DI/IoC pattern is to reduce the amount of direct coupling between different components of the application, the higher the dependency the more tightly coupled the application resulting in code which is hard to modify, unit test and mock.  Initializing Dependency Injection through BootStrapper TaxiClient is the starting project of the solution and App (App.xaml)  is the starting class that gets called when you run the application. From the App’s OnStartup method we will invoke BootStrapper.   namespace TaxiClient { /// <summary> /// Interaction logic for App.xaml /// </summary> public partial class App : Application { protected override void OnStartup(StartupEventArgs e) { base.OnStartup(e);   (new BootStrapper()).Run(); } } } BootStrapper is your contact point for initializing the application including dependency injection, creating Shell and other frameworks. We are going to use Unity for DI and there are lot of open source DI frameworks like Spring.Net, StructureMap etc with different feature set  and you can choose a framework based on your preferences. Note that Prism comes with in built support for Unity, for example we are deriving from UnityBootStrapper in our case and for any other DI framework you have to extend the Prism appropriately   namespace TaxiClient { public class BootStrapper: UnityBootstrapper { protected override IModuleCatalog CreateModuleCatalog() { return new ConfigurationModuleCatalog(); } protected override DependencyObject CreateShell() { Framework.FrameworkBootStrapper.Run(Container, Application.Current.Dispatcher);   Shell shell = new Shell(); shell.ResizeMode = ResizeMode.NoResize; shell.Show();   return shell; } } } Lets take a look into  FrameworkBootStrapper to check out how to register with unity container. namespace Framework { public class FrameworkBootStrapper { public static void Run(IUnityContainer container, Dispatcher dispatcher) { UIDispatcher uiDispatcher = new UIDispatcher(dispatcher); container.RegisterInstance<IDispatcherService>(uiDispatcher);   container.RegisterType<IInjectSingleViewService, InjectSingleViewService>( new ContainerControlledLifetimeManager());   . . . } } } In the above code we are registering two components with unity container. You shall observe that we are following two different approaches, RegisterInstance and RegisterType.  With RegisterInstance we are registering an existing instance and the same instance will be returned for every request made for IDispatcherService   and with RegisterType we are requesting unity container to create an instance for us when required, i.e., when I request for an instance for IInjectSingleViewService, unity will create/return an instance of InjectSingleViewService class and with RegisterType we can configure the life time of the instance being created. With ContaienrControllerLifetimeManager, the unity container caches the instance and reuses for any subsequent requests, without recreating a new instance. Lets take a look into FareViewModel.cs and it’s constructor. The constructor takes one parameter IEventAggregator and if you try to find all references in your solution for IEventAggregator, you will not find a single location where an instance of EventAggregator is passed directly to the constructor. The compiler still finds an instance and works fine because Prism is already configured when used with Unity container to return an instance of EventAggregator when requested for IEventAggregator and in this particular case it is called constructor injection. public class FareViewModel:ObservableBase, IDataErrorInfo { ... private IEventAggregator _eventAggregator;   public FareViewModel(IEventAggregator eventAggregator) { _eventAggregator = eventAggregator; InitializePropertyNames(); InitializeModel(); PropertyChanged += OnPropertyChanged; } ... 3. Shell Shells are very similar in operation to Master Pages in asp.net or MDI in Windows Forms. And shells contain regions which display the views, you can have as many regions as you wish in a given view. You can also nest regions. i.e, one region can load a view which in itself may contain other regions. We have to create a shell at the start of the application and are doing it by overriding CreateShell method from BootStrapper From the following Shell.xaml you shall notice that we have two content controls with Region names as ‘MenuRegion’ and ‘MainRegion’.  The idea here is that you can inject any user controls into the regions dynamically, i.e., a Menu User Control for MenuRegion and based on the user action you can load appropriate view into MainRegion.    <Window x:Class="TaxiClient.Shell" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:Regions="clr-namespace:Microsoft.Practices.Prism.Regions;assembly=Microsoft.Practices.Prism" Title="Taxi" Height="370" Width="800"> <Grid Margin="2"> <ContentControl Regions:RegionManager.RegionName="MenuRegion" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Stretch" />   <ContentControl Grid.Row="1" Regions:RegionManager.RegionName="MainRegion" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Stretch" /> <!--<Border Grid.ColumnSpan="2" BorderThickness="2" CornerRadius="3" BorderBrush="LightBlue" />-->   </Grid> </Window> 4. Modules Prism provides the ability to build composite applications and modules play an important role in it. For example if you are building a Mortgage Loan Processor application with 3 components, i.e. customer’s credit history,  existing mortgages, new home/loan information; and consider that the customer’s credit history component involves gathering data about his/her address, background information, job details etc. The idea here using Prism modules is to separate the implementation of these 3 components into their own visual studio projects allowing to build components with no dependency on each other and independently. If we need to add another component to the application, the component can be developed by in house team or some other team in the organization by starting with a new Visual Studio project and adding to the solution at the run time with very little knowledge about the application. Prism modules are defined by implementing the IModule interface and each visual studio project to be considered as a module should implement the IModule interface.  From the BootStrapper.cs you shall observe that we are overriding the method by returning a ConfiguratingModuleCatalog which returns the modules that are registered for the application using the app.config file  and you can also add module using code. Lets take a look into configuration file.   <?xml version="1.0"?> <configuration> <configSections> <section name="modules" type="Microsoft.Practices.Prism.Modularity.ModulesConfigurationSection, Microsoft.Practices.Prism"/> </configSections> <modules> <module assemblyFile="TaxiModules.dll" moduleType="TaxiModules.ModuleInitializer, TaxiModules" moduleName="TaxiModules"/> </modules> </configuration> Here we are adding TaxiModules project to our solution and TaxiModules.ModuleInitializer implements IModule interface   5. Module Mapper With Prism modules you can dynamically add or remove modules from the regions, apart from that Prism also provides API to control adding/removing the views from a region within the same module. Taxi Information Screen: Engage the Taxi Screen: The sample application has two screens, ‘Taxi Information’ and ‘Engage the Taxi’ and they both reside in same module, TaxiModules. ‘Engage the Taxi’ is again made of two user controls, FareView on the left and TotalView on the right. We have created a Shell with two regions, MenuRegion and MainRegion with menu loaded into MenuRegion. We can create a wrapper user control called EngageTheTaxi made of FareView and TotalView and load either TaxiInfo or EngageTheTaxi into MainRegion based on the user action. Though it will work it tightly binds the user controls and for every combination of user controls, we need to create a dummy wrapper control to contain them. Instead we can apply the principles we learned so far from Shell/regions and introduce another template (LeftAndRightRegionView.xaml) made of two regions Region1 (left) and Region2 (right) and load  FareView and TotalView dynamically.  To help with loading of the views dynamically I have introduce an helper an interface, IInjectSingleViewService,  idea suggested by Mike Taulty, a must read blog for .Net developers. using System; using System.Collections.Generic; using System.ComponentModel;   namespace Framework.PresentationUtility.Navigation {   public interface IInjectSingleViewService : INotifyPropertyChanged { IEnumerable<CommandViewDefinition> Commands { get; } IEnumerable<ModuleViewDefinition> Modules { get; }   void RegisterViewForRegion(string commandName, string viewName, string regionName, Type viewType); void ClearViewFromRegion(string viewName, string regionName); void RegisterModule(string moduleName, IList<ModuleMapper> moduleMappers); } } The Interface declares three methods to work with views: RegisterViewForRegion: Registers a view with a particular region. You can register multiple views and their regions under one command.  When this particular command is invoked all the views registered under it will be loaded into their regions. ClearViewFromRegion: To unload a specific view from a region. RegisterModule: The idea is when a command is invoked you can load the UI with set of controls in their default position and based on the user interaction, you can load different contols in to different regions on the fly.  And it is supported ModuleViewDefinition and ModuleMappers as shown below. namespace Framework.PresentationUtility.Navigation { public class ModuleViewDefinition { public string ModuleName { get; set; } public IList<ModuleMapper> ModuleMappers; public ICommand Command { get; set; } }   public class ModuleMapper { public string ViewName { get; set; } public string RegionName { get; set; } public Type ViewType { get; set; } } } 6. Event Aggregator Prism event aggregator enables messaging between components as in Observable pattern, Notifier notifies the Observer which receives notification it is interested in. When it comes to Observable pattern, Observer has to unsubscribes for notifications when it no longer interested in notifications, which allows the Notifier to remove the Observer’s reference from it’s local cache. Though .Net has managed garbage collection it cannot remove inactive the instances referenced by an active instance resulting in memory leak, keeping the Observers in memory as long as Notifier stays in memory.  Developers have to be very careful to unsubscribe when necessary and it often gets overlooked, to overcome these problems Prism Event Aggregator uses weak references to cache the reference (Observer in this case)  and releases the reference (memory) once the instance goes out of scope. Using event aggregator is very simple, declare a generic type of CompositePresenationEvent by inheriting from it. using Microsoft.Practices.Prism.Events; using TaxiCommon.BAO;   namespace TaxiCommon.CompositeEvents { public class TaxiOnMoveEvent:CompositePresentationEvent<TaxiOnMove> { } }   TaxiOnMove.cs includes the properties which we want to exchange between the parties, FareView and TotalView. using System;   namespace TaxiCommon.BAO { public class TaxiOnMove { public TimeSpan MinutesAtTweleveMPH { get; set; } public double MilesAtSixMPH { get; set; } } }   Lets take a look into FareViewodel (Notifier) and how it raises the event.  Here we are raising the event by getting the event through GetEvent<..>() and publishing it with the payload private void OnAddMinutes(object obj) { TaxiOnMove payload = new TaxiOnMove(); if(MilesAtSixMPH != null) payload.MilesAtSixMPH = MilesAtSixMPH.Value; if(MinutesAtTweleveMPH != null) payload.MinutesAtTweleveMPH = new TimeSpan(0,0,MinutesAtTweleveMPH.Value,0);   _eventAggregator.GetEvent<TaxiOnMoveEvent>().Publish(payload); ResetMinutesAndMiles(); } And TotalViewModel(Observer) subscribes to notifications by getting the event through GetEvent<..>() namespace TaxiModules.ViewModels { public class TotalViewModel:ObservableBase { .... private IEventAggregator _eventAggregator;   public TotalViewModel(IEventAggregator eventAggregator) { _eventAggregator = eventAggregator; ... }   private void SubscribeToEvents() { _eventAggregator.GetEvent<TaxiStartedEvent>() .Subscribe(OnTaxiStarted, ThreadOption.UIThread,false,(filter) => true); _eventAggregator.GetEvent<TaxiOnMoveEvent>() .Subscribe(OnTaxiMove, ThreadOption.UIThread, false, (filter) => true); _eventAggregator.GetEvent<TaxiResetEvent>() .Subscribe(OnTaxiReset, ThreadOption.UIThread, false, (filter) => true); }   ... private void OnTaxiMove(TaxiOnMove taxiOnMove) { OnMoveFare fare = new OnMoveFare(taxiOnMove); Fares.Add(fare); SetTotalFare(new []{fare}); }   .... 7. MVVM through example In this section we are going to look into MVVM implementation through example.  I have all the modules declared in a single project, TaxiModules, again it is not necessary to have them into one project. Once the user logs into the application, will be greeted with the ‘Engage the Taxi’ screen which is made of two user controls, FareView.xaml and TotalView.Xaml. As you can see from the solution explorer, each of them have their own code behind files and  ViewModel classes, FareViewMode.cs, TotalViewModel.cs Lets take a look in to the FareView and how it interacts with FareViewModel using MVVM implementation. FareView.xaml acts as a view and FareViewMode.cs is it’s view model. The FareView code behind class   namespace TaxiModules.Views { /// <summary> /// Interaction logic for FareView.xaml /// </summary> public partial class FareView : UserControl { public FareView(FareViewModel viewModel) { InitializeComponent(); this.Loaded += (s, e) => { this.DataContext = viewModel; }; } } } The FareView is bound to FareViewModel through the data context  and you shall observe that DataContext is of type Object, i.e. the FareView doesn’t really know the type of ViewModel (FareViewModel). This helps separation of View and ViewModel as View and ViewModel are independent of each other, you can bind FareView to FareViewModel2 as well and the application compiles just fine. Lets take a look into FareView xaml file  <UserControl x:Class="TaxiModules.Views.FareView" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:Toolkit="clr-namespace:Microsoft.Windows.Controls;assembly=WPFToolkit" xmlns:Commands="clr-namespace:Microsoft.Practices.Prism.Commands;assembly=Microsoft.Practices.Prism"> <Grid Margin="10" > ....   <Border Style="{DynamicResource innerBorder}" Grid.Row="0" Grid.Column="0" Grid.RowSpan="11" Grid.ColumnSpan="2" Panel.ZIndex="1"/>   <Label Grid.Row="0" Content="Engage the Taxi" Style="{DynamicResource innerHeader}"/> <Label Grid.Row="1" Content="Select the State"/> <ComboBox Grid.Row="1" Grid.Column="1" ItemsSource="{Binding States}" Height="auto"> <ComboBox.ItemTemplate> <DataTemplate> <TextBlock Text="{Binding Name}"/> </DataTemplate> </ComboBox.ItemTemplate> <ComboBox.SelectedItem> <Binding Path="SelectedState" Mode="TwoWay"/> </ComboBox.SelectedItem> </ComboBox> <Label Grid.Row="2" Content="Select the Date of Entry"/> <Toolkit:DatePicker Grid.Row="2" Grid.Column="1" SelectedDate="{Binding DateOfEntry, ValidatesOnDataErrors=true}" /> <Label Grid.Row="3" Content="Enter time 24hr format"/> <TextBox Grid.Row="3" Grid.Column="1" Text="{Binding TimeOfEntry, TargetNullValue=''}"/> <Button Grid.Row="4" Grid.Column="1" Content="Start the Meter" Commands:Click.Command="{Binding StartMeterCommand}" />   <Label Grid.Row="5" Content="Run the Taxi" Style="{DynamicResource innerHeader}"/> <Label Grid.Row="6" Content="Number of Miles &lt;@6mph"/> <TextBox Grid.Row="6" Grid.Column="1" Text="{Binding MilesAtSixMPH, TargetNullValue='', ValidatesOnDataErrors=true}"/> <Label Grid.Row="7" Content="Number of Minutes @12mph"/> <TextBox Grid.Row="7" Grid.Column="1" Text="{Binding MinutesAtTweleveMPH, TargetNullValue=''}"/> <Button Grid.Row="8" Grid.Column="1" Content="Add Minutes and Miles " Commands:Click.Command="{Binding AddMinutesCommand}"/> <Label Grid.Row="9" Content="Other Operations" Style="{DynamicResource innerHeader}"/> <Button Grid.Row="10" Grid.Column="1" Content="Reset the Meter" Commands:Click.Command="{Binding ResetCommand}"/>   </Grid> </UserControl> The highlighted code from the above code shows data binding, for example ComboBox which displays list of states has it’s ItemsSource bound to States property, with DataTemplate bound to Name and SelectedItem  to SelectedState. You might be wondering what are all these properties and how it is able to bind to them.  The answer lies in data context, i.e., when you bound a control, WPF looks for data context on the root object (Grid in this case) and if it can’t find data context it will look into root’s root, i.e. FareView UserControl and it is bound to FareViewModel.  Each of those properties have be declared on the ViewModel for the View to bind correctly. To put simply, View is bound to ViewModel through data context of type object and every control that is bound on the View actually binds to the public property on the ViewModel. Lets look into the ViewModel code (the following code is not an exact copy of FareViewMode.cs, pasted relevant code for this section)   namespace TaxiModules.ViewModels { public class FareViewModel:ObservableBase, IDataErrorInfo { public List<USState> States { get { return USStates.StateList; } }   public USState SelectedState { get { return _selectedState; } set { _selectedState = value; RaisePropertyChanged(_selectedStatePropertyName); } }   public DateTime? DateOfEntry { get { return _dateOfEntry; } set { _dateOfEntry = value; RaisePropertyChanged(_dateOfEntryPropertyName); } }   public TimeSpan? TimeOfEntry { get { return _timeOfEntry; } set { _timeOfEntry = value; RaisePropertyChanged(_timeOfEntryPropertyName); } }   public double? MilesAtSixMPH { get { return _milesAtSixMPH; } set { _milesAtSixMPH = value; RaisePropertyChanged(_distanceAtSixMPHPropertyName); } }   public int? MinutesAtTweleveMPH { get { return _minutesAtTweleveMPH; } set { _minutesAtTweleveMPH = value; RaisePropertyChanged(_minutesAtTweleveMPHPropertyName); } }   public ICommand StartMeterCommand { get { if(_startMeterCommand == null) { _startMeterCommand = new DelegateCommand<object>(OnStartMeter, CanStartMeter); } return _startMeterCommand; } }   public ICommand AddMinutesCommand { get { if(_addMinutesCommand == null) { _addMinutesCommand = new DelegateCommand<object>(OnAddMinutes, CanAddMinutes); } return _addMinutesCommand; } }   public ICommand ResetCommand { get { if(_resetCommand == null) { _resetCommand = new DelegateCommand<object>(OnResetCommand); } return _resetCommand; } }   } private void OnStartMeter(object obj) { _eventAggregator.GetEvent<TaxiStartedEvent>().Publish( new TaxiStarted() { EngagedOn = DateOfEntry.Value.Date + TimeOfEntry.Value, EngagedState = SelectedState.Value });   _isMeterStarted = true; OnPropertyChanged(this,null); } And views communicate user actions like button clicks, tree view item selections, etc using commands. When user clicks on ‘Start the Meter’ button it invokes the method StartMeterCommand, which calls the method OnStartMeter which publishes the event to TotalViewModel using event aggregator  and TaxiStartedEvent. namespace TaxiModules.ViewModels { public class TotalViewModel:ObservableBase { ... private IEventAggregator _eventAggregator;   public TotalViewModel(IEventAggregator eventAggregator) { _eventAggregator = eventAggregator;   InitializePropertyNames(); InitializeModel(); SubscribeToEvents(); }   public decimal? TotalFare { get { return _totalFare; } set { _totalFare = value; RaisePropertyChanged(_totalFarePropertyName); } } .... private void SubscribeToEvents() { _eventAggregator.GetEvent<TaxiStartedEvent>().Subscribe(OnTaxiStarted, ThreadOption.UIThread,false,(filter) => true); _eventAggregator.GetEvent<TaxiOnMoveEvent>().Subscribe(OnTaxiMove, ThreadOption.UIThread, false, (filter) => true); _eventAggregator.GetEvent<TaxiResetEvent>().Subscribe(OnTaxiReset, ThreadOption.UIThread, false, (filter) => true); }   private void OnTaxiStarted(TaxiStarted taxiStarted) { Fares.Add(new EntryFare()); Fares.Add(new StateTaxFare(taxiStarted)); Fares.Add(new NightSurchargeFare(taxiStarted)); Fares.Add(new PeakHourWeekdayFare(taxiStarted));   SetTotalFare(Fares); }   private void SetTotalFare(IEnumerable<IFare> fares) { TotalFare = (_totalFare ?? 0) + TaxiFareHelper.GetTotalFare(fares); } ....   } }   TotalViewModel subscribes to events, TaxiStartedEvent and rest. When TaxiStartedEvent gets invoked it calls the OnTaxiStarted method which sets the total fare which includes entry fee, state tax, nightly surcharge, peak hour weekday fare.   Note that TotalViewModel derives from ObservableBase which implements the method RaisePropertyChanged which we are invoking in Set of TotalFare property, i.e, once we update the TotalFare property it raises an the event that  allows the TotalFare text box to fetch the new value through the data context. ViewModel is communicating with View through data context and it has no knowledge about View, helping in loose coupling of ViewModel and View.   I have attached the source code (.Net 4.0, Prism 4.0, VS 2010) , download and play with it and don’t forget to leave your comments.  

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• Adventures in MVVM &ndash; My ViewModel Base

  - by Brian Genisio's House Of Bilz

  More Adventures in MVVM First, I’d like to say: THIS IS NOT A NEW MVVM FRAMEWORK. I tend to believe that MVVM support code should be specific to the system you are building and the developers working on it.  I have yet to find an MVVM framework that does everything I want it to without doing too much.  Don’t get me wrong… there are some good frameworks out there.  I just like to pick and choose things that make sense for me.  I’d also like to add that some of these features only work in WPF.  As of Silveright 4, they don’t support binding to dynamic properties, so some of the capabilities are lost. That being said, I want to share my ViewModel base class with the world.  I have had several conversations with people about the problems I have solved using this ViewModel base.  A while back, I posted an article about some experiments with a “Rails Inspired ViewModel”.  What followed from those ideas was a ViewModel base class that I take with me and use in my projects.  It has a lot of features, all designed to reduce the friction in writing view models. I have put the code out on Codeplex under the project: ViewModelSupport. Finally, this article focuses on the ViewModel and only glosses over the View and the Model.  Without all three, you don’t have MVVM.  But this base class is for the ViewModel, so that is what I am focusing on. Features: Automatic Command Plumbing Property Change Notification Strongly Typed Property Getter/Setters Dynamic Properties Default Property values Derived Properties Automatic Method Execution Command CanExecute Change Notification Design-Time Detection What about Silverlight? Automatic Command Plumbing This feature takes the plumbing out of creating commands.  The common pattern for commands in a ViewModel is to have an Execute method as well as an optional CanExecute method.  To plumb that together, you create an ICommand Property, and set it in the constructor like so: Before public class AutomaticCommandViewModel { public AutomaticCommandViewModel() { MyCommand = new DelegateCommand(Execute_MyCommand, CanExecute_MyCommand); } public void Execute_MyCommand() { // Do something } public bool CanExecute_MyCommand() { // Are we in a state to do something? return true; } public DelegateCommand MyCommand { get; private set; } } With the base class, this plumbing is automatic and the property (MyCommand of type ICommand) is created for you.  The base class uses the convention that methods be prefixed with Execute_ and CanExecute_ in order to be plumbed into commands with the property name after the prefix.  You are left to be expressive with your behavior without the plumbing.  If you are wondering how CanExecuteChanged is raised, see the later section “Command CanExecute Change Notification”. After public class AutomaticCommandViewModel : ViewModelBase { public void Execute_MyCommand() { // Do something } public bool CanExecute_MyCommand() { // Are we in a state to do something? return true; } }   Property Change Notification One thing that always kills me when implementing ViewModels is how to make properties that notify when they change (via the INotifyPropertyChanged interface).  There have been many attempts to make this more automatic.  My base class includes one option.  There are others, but I feel like this works best for me. The common pattern (without my base class) is to create a private backing store for the variable and specify a getter that returns the private field.  The setter will set the private field and fire an event that notifies the change, only if the value has changed. Before public class PropertyHelpersViewModel : INotifyPropertyChanged { private string text; public string Text { get { return text; } set { if(text != value) { text = value; RaisePropertyChanged("Text"); } } } protected void RaisePropertyChanged(string propertyName) { var handlers = PropertyChanged; if(handlers != null) handlers(this, new PropertyChangedEventArgs(propertyName)); } public event PropertyChangedEventHandler PropertyChanged; } This way of defining properties is error-prone and tedious.  Too much plumbing.  My base class eliminates much of that plumbing with the same functionality: After public class PropertyHelpersViewModel : ViewModelBase { public string Text { get { return Get<string>("Text"); } set { Set("Text", value);} } }   Strongly Typed Property Getters/Setters It turns out that we can do better than that.  We are using a strongly typed language where the use of “Magic Strings” is often frowned upon.  Lets make the names in the getters and setters strongly typed: A refinement public class PropertyHelpersViewModel : ViewModelBase { public string Text { get { return Get(() => Text); } set { Set(() => Text, value); } } }   Dynamic Properties In C# 4.0, we have the ability to program statically OR dynamically.  This base class lets us leverage the powerful dynamic capabilities in our ecosystem. (This is how the automatic commands are implemented, BTW)  By calling Set(“Foo”, 1), you have now created a dynamic property called Foo.  It can be bound against like any static property.  The opportunities are endless.  One great way to exploit this behavior is if you have a customizable view engine with templates that bind to properties defined by the user.  The base class just needs to create the dynamic properties at runtime from information in the model, and the custom template can bind even though the static properties do not exist. All dynamic properties still benefit from the notifiable capabilities that static properties do. For any nay-sayers out there that don’t like using the dynamic features of C#, just remember this: the act of binding the View to a ViewModel is dynamic already.  Why not exploit it?  Get over it :) Just declare the property dynamically public class DynamicPropertyViewModel : ViewModelBase { public DynamicPropertyViewModel() { Set("Foo", "Bar"); } } Then reference it normally <TextBlock Text="{Binding Foo}" />   Default Property Values The Get() method also allows for default properties to be set.  Don’t set them in the constructor.  Set them in the property and keep the related code together: public string Text { get { return Get(() => Text, "This is the default value"); } set { Set(() => Text, value);} }   Derived Properties This is something I blogged about a while back in more detail.  This feature came from the chaining of property notifications when one property affects the results of another, like this: Before public class DependantPropertiesViewModel : ViewModelBase { public double Score { get { return Get(() => Score); } set { Set(() => Score, value); RaisePropertyChanged("Percentage"); RaisePropertyChanged("Output"); } } public int Percentage { get { return (int)(100 * Score); } } public string Output { get { return "You scored " + Percentage + "%."; } } } The problem is: The setter for Score has to be responsible for notifying the world that Percentage and Output have also changed.  This, to me, is backwards.    It certainly violates the “Single Responsibility Principle.” I have been bitten in the rear more than once by problems created from code like this.  What we really want to do is invert the dependency.  Let the Percentage property declare that it changes when the Score Property changes. After public class DependantPropertiesViewModel : ViewModelBase { public double Score { get { return Get(() => Score); } set { Set(() => Score, value); } } [DependsUpon("Score")] public int Percentage { get { return (int)(100 * Score); } } [DependsUpon("Percentage")] public string Output { get { return "You scored " + Percentage + "%."; } } }   Automatic Method Execution This one is extremely similar to the previous, but it deals with method execution as opposed to property.  When you want to execute a method triggered by property changes, let the method declare the dependency instead of the other way around. Before public class DependantMethodsViewModel : ViewModelBase { public double Score { get { return Get(() => Score); } set { Set(() => Score, value); WhenScoreChanges(); } } public void WhenScoreChanges() { // Handle this case } } After public class DependantMethodsViewModel : ViewModelBase { public double Score { get { return Get(() => Score); } set { Set(() => Score, value); } } [DependsUpon("Score")] public void WhenScoreChanges() { // Handle this case } }   Command CanExecute Change Notification Back to Commands.  One of the responsibilities of commands that implement ICommand – it must fire an event declaring that CanExecute() needs to be re-evaluated.  I wanted to wait until we got past a few concepts before explaining this behavior.  You can use the same mechanism here to fire off the change.  In the CanExecute_ method, declare the property that it depends upon.  When that property changes, the command will fire a CanExecuteChanged event, telling the View to re-evaluate the state of the command.  The View will make appropriate adjustments, like disabling the button. DependsUpon works on CanExecute methods as well public class CanExecuteViewModel : ViewModelBase { public void Execute_MakeLower() { Output = Input.ToLower(); } [DependsUpon("Input")] public bool CanExecute_MakeLower() { return !string.IsNullOrWhiteSpace(Input); } public string Input { get { return Get(() => Input); } set { Set(() => Input, value);} } public string Output { get { return Get(() => Output); } set { Set(() => Output, value); } } }   Design-Time Detection If you want to add design-time data to your ViewModel, the base class has a property that lets you ask if you are in the designer.  You can then set some default values that let your designer see what things might look like in runtime. Use the IsInDesignMode property public DependantPropertiesViewModel() { if(IsInDesignMode) { Score = .5; } }   What About Silverlight? Some of the features in this base class only work in WPF.  As of version 4, Silverlight does not support binding to dynamic properties.  This, in my opinion, is a HUGE limitation.  Not only does it keep you from using many of the features in this ViewModel, it also keeps you from binding to ViewModels designed in IronRuby.  Does this mean that the base class will not work in Silverlight?  No.  Many of the features outlined in this article WILL work.  All of the property abstractions are functional, as long as you refer to them statically in the View.  This, of course, means that the automatic command hook-up doesn’t work in Silverlight.  You need to plumb it to a static property in order for the Silverlight View to bind to it.  Can I has a dynamic property in SL5?     Good to go? So, that concludes the feature explanation of my ViewModel base class.  Feel free to take it, fork it, whatever.  It is hosted on CodePlex.  When I find other useful additions, I will add them to the public repository.  I use this base class every day.  It is mature, and well tested.  If, however, you find any problems with it, please let me know!  Also, feel free to suggest patches to me via the CodePlex site.  :)

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• Distinguishing between UI command & domain commands

  - by SonOfPirate

  I am building a WPF client application using the MVVM pattern that provides an interface on top of an existing set of business logic residing in a library which is shared with other applications. The business library followed a domain-driven architecture using CQRS to separate the read and write models (no event sourcing). The combination of technologies and patterns has brought up an interesting conundrum: The MVVM pattern uses the command pattern for handling user-interaction with the view models. .NET provides an ICommand interface which is implemented by most MVVM frameworks, like MVVM Light's RelayCommand and Prism's DelegateCommand. For example, the view model would expose a number of command objects as properties that are bound to the UI and respond when the user performs actions like clicking buttons. Many implementations of the CQRS use the command pattern to isolate and encapsulate individual behaviors. In my business library, we have implemented the write model as command / command-handler pairs. As such, when we want to do some work, such as create a new order, we 'issue' a command (CreateOrderCommand) which is routed to the command-handler responsible for executing the command. This is great, clearly explained in many sources and I am good with it. However, take this scenario: I have a ToolbarViewModel which exposes a CreateNewOrderCommand property. This ICommand object is bound to a button in the UI. When clicked, the UI command creates and issues a new CreateOrderCommand object to the domain which is handled by the CreateOrderCommandHandler. This is difficult to explain to other developers and I am finding myself getting tongue-tied because everything is a command. I'm sure I'm not the first developer to have patterns overlap like this where the naming/terminology also overlap. How have you approached distinguishing your commands used in the UI from those used in the domain? (Edit: I should mention that the business library is UI-agnostic, i.e. no UI technology-specific code exists, or will exists, in this library.)

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• MVVM in Task-It

  As I'm gearing up to write a post about dynamic XAP loading with MEF, I'd like to first talk a bit about MVVM, the Model-View-ViewModel pattern, as I will be leveraging this pattern in my future posts. Download Source Code Why MVVM? Your first question may be, "why do I need this pattern? I've been using a code-behind approach for years and it works fine." Well, you really don't have to make the switch to MVVM, but let me first explain some of the benefits I see for doing so. MVVM Benefits Testability - This is the one you'll probably hear the most about when it comes to MVVM. Moving most of the code from your code-behind to a separate view model class means you can now write unit tests against the view model without any knowledge of a view (UserControl). Multiple UIs - Let's just say that you've created a killer app, it's running in the browser, and maybe you've even made it run out-of-browser. Now what if your boss comes to you and says, "I heard about this new Windows Phone 7 device that is coming out later this year. Can you start porting the app to that device?". Well, now you have to create a new UI (UserControls, etc.) because you have a lot less screen real estate to work with. So what do you do, copy all of your existing UserControls, paste them, rename them, and then start changing the code? Hmm, that doesn't sound so good. But wait, if most of the code that makes your browser-based app tick lives in view model classes, now you can create new view (UserControls) for Windows Phone 7 that reference the same view model classes as your browser-based app. Page state - In Silverlight you're at some point going to be faced with the same issue you dealt with for years in ASP.NET, maintaining page state. Let's say a user hits your Products page, does some stuff (filters record, etc.), then leaves the page and comes back later. It would be best if the Products page was in the same state as when they left it right? Well, if you've thrown away your view (UserControl or Page) and moved off to another part of the UI, when you come back to Products you're probably going to re-instantiate your view...which will put it right back in the state it was when it started. Hmm, not good. Well, with a little help from MEF you can store the state in your view model class, MEF will keep that view model instance hanging around in memory, and then you simply rebind your view to the view model class. I made that sound easy, but it's actually a bit of work to properly store and restore the state. At least it can be done though, which will make your users a lot happier! I'll talk more about this in an upcoming blog post. No event handlers? Another nice thing about MVVM is that you can bind your UserControls to the view model, which may eliminate the need for event handlers in your code-behind. So instead of having a Click handler on a Button (or RadMenuItem), for example, you can now bind your control's Command property to a DelegateCommand in your view model (I'll talk more about Commands in an upcoming post). Instead of having a SelectionChanged event handler on your RadGridView you can now bind its SelectedItem property to a property in your view model, and each time the user clicks a row, the view model property's setter will be called. Now through the magic of binding we can eliminate the need for traditional code-behind based event handlers on our user interface controls, and the best thing is that the view model knows about everything that's going on...which means we can test things without a user interface. The brains of the operation So what we're seeing here is that the view is now just a dumb layer that binds to the view model, and that the view model is in control of just about everything, like what happens when a RadGridView row is selected, or when a RadComboBoxItem is selected, or when a RadMenuItem is clicked. It is also responsible for loading data when the page is hit, as well as kicking off data inserts, updates and deletions. Once again, all of this stuff can be tested without the need for a user interface. If the test works, then it'll work regardless of whether the user is hitting the browser-based version of your app, or the Windows Phone 7 version. Nice! The database Before running the code for this app you will need to create the database. First, create a database called MVVMProject in SQL Server, then run MVVMProject.sql in the MVVMProject/Database directory of your downloaded .zip file. This should give you a Task table with 3 records in it. When you fire up the solution you will also need to update the connection string in web.config to point to your database instead of IBM12\SQLSERVER2008. The code One note about this code is that it runs against the latest Silverlight 4 RC and WCF RIA Services code. Please see my first blog post about updating to the RC bits. Beta to RC - Part 1 At the top of this post is a link to a sample project that demonstrates a sample application with a Tasks page that uses the MVVM pattern. This is a simplified version of how I have implemented the Tasks page in the Task-It application. Youll notice that Tasks.xaml has very little code to it. Just a TextBlock that displays the page title and a ContentControl. <StackPanel>     <TextBlock Text="Tasks" Style="{StaticResource PageTitleStyle}"/>     <Rectangle Style="{StaticResource StandardSpacerStyle}"/>     <ContentControl x:Name="ContentControl1"/> </StackPanel> In List.xaml we have a RadGridView. Notice that the ItemsSource is bound to a property in the view model class call Tasks, SelectedItem is bound to a property in the view model called SelectedItem, and IsBusy is bound to a property in the view model called IsLoading. <Grid>     <telerikGridView:RadGridView ItemsSource="{Binding Tasks}" SelectedItem="{Binding SelectedItem, Mode=TwoWay}"                                  IsBusy="{Binding IsLoading}" AutoGenerateColumns="False" IsReadOnly="True" RowIndicatorVisibility="Collapsed"                IsFilteringAllowed="False" ShowGroupPanel="False">         <telerikGridView:RadGridView.Columns>             <telerikGridView:GridViewDataColumn Header="Name" DataMemberBinding="{Binding Name}" Width="3*"/>             <telerikGridView:GridViewDataColumn Header="Due" DataMemberBinding="{Binding DueDate}" DataFormatString="{}{0:d}" Width="*"/>         </telerikGridView:RadGridView.Columns>     </telerikGridView:RadGridView> </Grid> In Details.xaml we have a Save button that is bound to a property called SaveCommand in our view model. We also have a simple form (Im using a couple of controls here from Silverlight.FX for the form layout, FormPanel and Label simply because they make for a clean XAML layout). Notice that the FormPanel is also bound to the SelectedItem in the view model (the same one that the RadGridView is). The two form controls, the TextBox and RadDatePicker) are bound to the SelectedItem's Name and DueDate properties. These are properties of the Task object that WCF RIA Services creates. <StackPanel>     <Button Content="Save" Command="{Binding SaveCommand}" HorizontalAlignment="Left"/>     <Rectangle Style="{StaticResource StandardSpacerStyle}"/>     <fxui:FormPanel DataContext="{Binding SelectedItem}" Style="{StaticResource FormContainerStyle}">         <fxui:Label Text="Name:"/>         <TextBox Text="{Binding Name, Mode=TwoWay}"/>         <fxui:Label Text="Due:"/>         <telerikInput:RadDatePicker SelectedDate="{Binding DueDate, Mode=TwoWay}"/>     </fxui:FormPanel> </StackPanel> In the code-behind of the Tasks control, Tasks.xaml.cs, I created an instance of the view model class (TasksViewModel) in the constructor and set it as the DataContext for the control. The Tasks page will load one of two child UserControls depending on whether you are viewing the list of tasks (List.xaml) or the form for editing a task (Details.xaml). // Set the DataContext to an instance of the view model class var viewModel = new TasksViewModel(); DataContext = viewModel;   // Child user controls (inherit DataContext from this user control) List = new List(); // RadGridView Details = new Details(); // Form When the page first loads, the List is loaded into the ContentControl. // Show the RadGridView first ContentControl1.Content = List; In the code-behind we also listen for a couple of the view models events. The ItemSelected event will be fired when the user clicks on a record in the RadGridView in the List control. The SaveCompleted event will be fired when the user clicks Save in the Details control (the form). Here the view model is in control, and is letting the view know when something needs to change. // Listeners for the view model's events viewModel.ItemSelected += OnItemSelected; viewModel.SaveCompleted += OnSaveCompleted; The event handlers toggle the view between the RadGridView (List) and the form (Details). void OnItemSelected(object sender, RoutedEventArgs e) {     // Show the form     ContentControl1.Content = Details; }   void OnSaveCompleted(object sender, RoutedEventArgs e) {     // Show the RadGridView     ContentControl1.Content = List; } In TasksViewModel, we instantiate a DataContext object and a SaveCommand in the constructor. DataContext is a WCF RIA Services object that well use to retrieve the list of Tasks and to save any changes to a task. Ill talk more about this and Commands in future post, but for now think of the SaveCommand as an event handler that is called when the Save button in the form is clicked. DataContext = new DataContext(); SaveCommand = new DelegateCommand(OnSave); When the TasksViewModel constructor is called we also make a call to LoadTasks. This sets IsLoading to true (which causes the RadGridViews busy indicator to appear) and retrieves the records via WCF RIA Services.         public LoadOperation<Task> LoadTasks()         {             // Show the loading message             IsLoading = true;             // Get the data via WCF RIA Services. When the call has returned, called OnTasksLoaded.             return DataContext.Load(DataContext.GetTasksQuery(), OnTasksLoaded, false);         } When the data is returned, OnTasksLoaded is called. This sets IsLoading to false (which hides the RadGridViews busy indicator), and fires property changed notifications to the UI to let it know that the IsLoading and Tasks properties have changed. This property changed notification basically tells the UI to rebind. void OnTasksLoaded(LoadOperation<Task> lo) {     // Hide the loading message     IsLoading = false;       // Notify the UI that Tasks and IsLoading properties have changed     this.OnPropertyChanged(p => p.Tasks);     this.OnPropertyChanged(p => p.IsLoading); } Next lets look at the view models SelectedItem property. This is the one thats bound to both the RadGridView and the form. When the user clicks a record in the RadGridView its setter gets called (set a breakpoint and see what I mean). The other code in the setter lets the UI know that the SelectedItem has changed (so the form displays the correct data), and fires the event that notifies the UI that a selection has occurred (which tells the UI to switch from List to Details). public Task SelectedItem {     get { return _selectedItem; }     set     {         _selectedItem = value;           // Let the UI know that the SelectedItem has changed (forces it to re-bind)         this.OnPropertyChanged(p => p.SelectedItem);         // Notify the UI, so it can switch to the Details (form) page         NotifyItemSelected();     } } One last thing, saving the data. When the Save button in the form is clicked it fires the SaveCommand, which calls the OnSave method in the view model (once again, set a breakpoint to see it in action). public void OnSave() {     // Save the changes via WCF RIA Services. When the save is complete, call OnSaveCompleted.     DataContext.SubmitChanges(OnSaveCompleted, null); } In OnSave, we tell WCF RIA Services to submit any changes, which there will be if you changed either the Name or the Due Date in the form. When the save is completed, it calls OnSaveCompleted. This method fires a notification back to the UI that the save is completed, which causes the RadGridView (List) to show again. public virtual void OnSaveCompleted(SubmitOperation so) {     // Clear the item that is selected in the grid (in case we want to select it again)     SelectedItem = null;     // Notify the UI, so it can switch back to the List (RadGridView) page     NotifySaveCompleted(); } Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• MVVM (ICommand) in Silverlight

  - by Andrey Khataev

  Hello! Please, don't judge strictly if this question was discussed previously or indirectly answered in huge nearby prism and mvvm blogs. In WPF implementation of RelayCommand or DelegateCommand classes there is a such eventhandler /// <summary> /// Occurs whenever the state of the application changes such that the result of a call to <see cref="CanExecute"/> may return a different value. /// </summary> public event EventHandler CanExecuteChanged { add { CommandManager.RequerySuggested += value; } remove { CommandManager.RequerySuggested -= value; } } but in SL subset of namespaces there are no CommandManager class. And this is where I'm stuck. I haven't yet found an workaround for this in MVVM adoptation for SL (PRISM is so complex for me yet). Different simple HelloWorldMVVM apps don't deal with at all. Thanks in advance and sorry for my English -)

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• Activate WPF command based on TextBox value

  - by zendar

  This is MVVM application. I have form and related view model class. There is TextBox, Button and ListBox on form. Button is bound to DelegateCommand that has CanExecute function. Idea is that user enters some data in text box, presses button and data is appended to list box. I would like to enable command (and button) when user enters correct data in TextBox. Things look like this now: CanExecute() contains code that checks if data in property bound to text box is correct. Text box is bound to property in view model UpdateSourceTrigger is set to PropertyChanged and property in view model is updated after each key user presses. Problem is that CanExecute() does not fire when user enters data in text box. It doesn't fire even when text box lose focus. How could I make this work?

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