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  • Setting a Visual State from a data bound enum in WPF

    - by firoso
    Hey all, I've got a scenario where I want to switch the visiblity of 4 different content controls. The visual states I have set opacity, and collapsed based on each given state (See code.) What I'd like to do is have the visual state bound to a property of my View Model of type Enum. I tried using DataStateBehavior, but it requires true/false, which doesn't work for me. So I tried DataStateSwitchBehavior, which seems to be totally broken for WPF4 from what I could tell. Is there a better way to be doing this? I'm really open to different approaches if need be, but I'd really like to keep this enum in the equation. Edit: The code shouldn't be too important, I just need to know if there's a well known solution to this problem. <UserControl xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:Custom="http://schemas.microsoft.com/expression/2010/interactivity" xmlns:ei="http://schemas.microsoft.com/expression/2010/interactions" xmlns:ee="http://schemas.microsoft.com/expression/2010/effects" xmlns:customBehaviors="clr-namespace:SEL.MfgTestDev.ESS.Behaviors" x:Class="SEL.MfgTestDev.ESS.View.PresenterControl" mc:Ignorable="d" d:DesignHeight="624" d:DesignWidth="1104" d:DataContext="{Binding ApplicationViewModel, Mode=OneWay, Source={StaticResource Locator}}"> <Grid> <Grid.Resources> <ResourceDictionary> <ResourceDictionary.MergedDictionaries> <ResourceDictionary Source="Layout/TerminalViewTemplate.xaml"/> <ResourceDictionary Source="Layout/DebugViewTemplate.xaml"/> <ResourceDictionary Source="Layout/ProgressViewTemplate.xaml"/> <ResourceDictionary Source="Layout/LoadoutViewTemplate.xaml"/> </ResourceDictionary.MergedDictionaries> </ResourceDictionary> </Grid.Resources> <Custom:Interaction.Behaviors> <customBehaviors:DataStateSwitchBehavior Binding="{Binding ApplicationViewState}"> <customBehaviors:DataStateSwitchCase State="LoadoutState" Value="Loadout"/> </customBehaviors:DataStateSwitchBehavior> </Custom:Interaction.Behaviors> <VisualStateManager.VisualStateGroups> <VisualStateGroup x:Name="ApplicationStates" ei:ExtendedVisualStateManager.UseFluidLayout="True"> <VisualStateGroup.Transitions> <VisualTransition GeneratedDuration="0:0:1"> <VisualTransition.GeneratedEasingFunction> <SineEase EasingMode="EaseInOut"/> </VisualTransition.GeneratedEasingFunction> <ei:ExtendedVisualStateManager.TransitionEffect> <ee:SmoothSwirlGridTransitionEffect/> </ei:ExtendedVisualStateManager.TransitionEffect> </VisualTransition> </VisualStateGroup.Transitions> <VisualState x:Name="LoadoutState"> <Storyboard> <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="LoadoutPage"> <EasingDoubleKeyFrame KeyTime="0" Value="1"/> </DoubleAnimationUsingKeyFrames> <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="LoadoutPage"> <DiscreteObjectKeyFrame KeyTime="0" Value="{x:Static Visibility.Visible}"/> </ObjectAnimationUsingKeyFrames> </Storyboard> </VisualState> <VisualState x:Name="ProgressState"> <Storyboard> <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="ProgressPage"> <EasingDoubleKeyFrame KeyTime="0" Value="1"/> </DoubleAnimationUsingKeyFrames> <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="ProgressPage"> <DiscreteObjectKeyFrame KeyTime="0" Value="{x:Static Visibility.Visible}"/> </ObjectAnimationUsingKeyFrames> </Storyboard> </VisualState> <VisualState x:Name="DebugState"> <Storyboard> <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="DebugPage"> <DiscreteObjectKeyFrame KeyTime="0" Value="{x:Static Visibility.Visible}"/> </ObjectAnimationUsingKeyFrames> <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="DebugPage"> <EasingDoubleKeyFrame KeyTime="0" Value="1"/> </DoubleAnimationUsingKeyFrames> </Storyboard> </VisualState> <VisualState x:Name="TerminalState"> <Storyboard> <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="TerminalPage"> <DiscreteObjectKeyFrame KeyTime="0" Value="{x:Static Visibility.Visible}"/> </ObjectAnimationUsingKeyFrames> <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="TerminalPage"> <EasingDoubleKeyFrame KeyTime="0" Value="1"/> </DoubleAnimationUsingKeyFrames> </Storyboard> </VisualState> </VisualStateGroup> </VisualStateManager.VisualStateGroups> <ContentControl x:Name="LoadoutPage" ContentTemplate="{StaticResource LoadoutViewTemplate}" Opacity="0" Content="{Binding}" Visibility="Collapsed"/> <ContentControl x:Name="ProgressPage" ContentTemplate="{StaticResource ProgressViewTemplate}" Opacity="0" Content="{Binding}" Visibility="Collapsed"/> <ContentControl x:Name="DebugPage" ContentTemplate="{StaticResource DebugViewTemplate}" Opacity="0" Content="{Binding}" Visibility="Collapsed"/> <ContentControl x:Name="TerminalPage" ContentTemplate="{StaticResource TerminalViewTemplate}" Opacity="0" Content="{Binding}" Visibility="Collapsed"/> <TextBlock HorizontalAlignment="Left" TextWrapping="Wrap" VerticalAlignment="Top" Text="{Binding ApplicationViewState}"> <TextBlock.Background> <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0"> <GradientStop Color="Black" Offset="0"/> <GradientStop Color="White" Offset="1"/> </LinearGradientBrush> </TextBlock.Background> </TextBlock> </Grid>

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  • How to pass EventArgument information from view to view model in WPF?

    - by Ashish Ashu
    I have ListView control in my application which is binded to the collection of CustomObject List<CustomObject. The CustomObject has seperate view. This ListView has seperate view model. The collection List _customobject is containted in the ListView ViewModel class. My Query: I want to invoke a view that show properties of custom object, when user double click on any row of ListView. The ListView double click command is binded to the ListViewDoublClick Command in the view model. The CustomObject is in the event argument of listview double click command. To acheive this I have to pass the custom object ( or an unique id property of custom object through which I can retrieve the custom object from the collection) as command parameter. Please suggest me the solution!!

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  • How do I keep my DataService up to date with ObservableCollection?

    - by joebeazelman
    I have a class called CustomerService which simply reads a collection of customers from a file or creates one and passes it back to the Main Model View where it is turned into an ObservableCollection. What the best practice for making sure the items in the CustomerService and ObservableCollection are in sync. I'm guessing I could hookup the CustomerService object to respond to RaisePropertyChanged, but isn't this only for use with WPF controls? Is there a better way? using System; public class MainModelView { public MainModelView() { _customers = new ObservableCollection<CustomerViewModel>(new CustomerService().GetCustomers()); } public const string CustomersPropertyName = "Customers" private ObservableCollection<CustomerViewModel> _customers; public ObservableCollection<CustomerViewModel> Customers { get { return _customers; } set { if (_customers == value) { return; } var oldValue = _customers; _customers = value; // Update bindings and broadcast change using GalaSoft.MvvmLight.Messenging RaisePropertyChanged(CustomersPropertyName, oldValue, value, true); } } } public class CustomerService { /// <summary> /// Load all persons from file on disk. /// </summary> _customers = new List<CustomerViewModel> { new CustomerViewModel(new Customer("Bob", "" )), new CustomerViewModel(new Customer("Bob 2", "" )), new CustomerViewModel(new Customer("Bob 3", "" )), }; public IEnumerable<LinkViewModel> GetCustomers() { return _customers; } }

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  • What&rsquo;s new in MVVM Light V3

    - by Laurent Bugnion
    V3 of the MVVM Light Toolkit was released during MIX10, after quite a long alpha stage. This post lists the new features in MVVM Light V3. Compatibility MVVM Light Toolkit V3 can be installed for the following tools and framework versions: Visual Studio 2008 SP1, Expression Blend 3 Windows Presentation Foundation 3.5 SP1 Silverlight 3 Visual Studio 2010 RC, Expression Blend 4 beta Windows Presentation Foundation 3.5 SP1 Windows Presentation Foundation 4 RC Silverlight 3 Silverlight 4 RC For more information about installing the MVVM Light Toolkit V3, please visit this page. For cleaning up existing installation, see this page. New in V3 RTM The following features have been added after V3 alpha3: Project template for the Windows Phone 7 series (Silverlight) This new template allows you to create a new MVVM Light application in Visual Studio 2010 RC and to run it in the Windows Phone 7 series emulator. This template uses the Silverlight 3 version of the MVVM Light Toolkit V3. At this time, only the essentials features of the GalaSoft.MvvmLight.dll assembly are supported on the phone. New in V3 alpha3 The following features have been added after V3 alpha2: New logo An awesome logo has been designed for MVVM Light by Philippe Schutz. DispatcherHelper class (in GalaSoft.MvvmLight.Extras.dll) This class is useful when you work on multi-threaded WPF or Silverlight applications. Initializing: The DispatcherHelper class must be initialized in the UI thread. For example, you can initialize the class in a Silverlight application’s Application_Startup event handler, or in the WPF application’s static App constructor (in App.xaml). // Initializing in Silverlight (in App.xaml) private void Application_Startup( object sender, StartupEventArgs e) { RootVisual = new MainPage(); DispatcherHelper.Initialize(); } // Initializing in WPF (in App.xaml) static App() { DispatcherHelper.Initialize(); } Verifying if a property exists The ViewModelBase.RaisePropertyChanged method now checks if a given property name exists on the ViewModel class, and throws an exception if that property cannot be found. This is useful to detect typos in a property name, for example during a refactoring. Note that the check is only done in DEBUG mode. Replacing IDisposable with ICleanup The IDisposable implementation in the ViewModelBase class has been marked obsolete. Instead, the ICleanup interface (and its Cleanup method) has been added. Implementing IDisposable in a ViewModel is still possible, but must be done explicitly. IDisposable in ViewModelBase was a bad practice, because it supposes that the ViewModel is garbage collected after Dispose is called. instead, the Cleanup method does not have such expectation. The ViewModelLocator class (created when an MVVM Light project template is used in Visual Studio or Expression Blend) exposes a static Cleanup method, which should in turn call each ViewModel’s Cleanup method. The ViewModel is free to override the Cleanup method if local cleanup must be performed. Passing EventArgs to command with EventToCommand The EventToCommand class is used to bind any event to an ICommand (typically on the ViewModel). In this case, it can be useful to pass the event’s EventArgs parameter to the command in the ViewModel. For example, for the MouseEnter event, you can pass the MouseEventArgs to a RelayCommand<MouseEventArgs> as shown in the next listings. Note: Bringing UI specific classes (such as EventArgs) into the ViewModel reduces the testability of the ViewModel, and thus should be used with care. Setting EventToCommand and PassEventArgsToCommand: <Grid x:Name="LayoutRoot"> <i:Interaction.Triggers> <i:EventTrigger EventName="MouseEnter"> <cmd:EventToCommand Command="{Binding MyCommand}" PassEventArgsToCommand="True" /> </i:EventTrigger> </i:Interaction.Triggers> </Grid> Getting the EventArgs in the command public RelayCommand<MouseEventArgs> MyCommand { get; private set; } public MainViewModel() { MyCommand = new RelayCommand<MouseEventArgs>(e => { // e is of type MouseEventArgs }); } Changes to templates Various changes have been made to project templates and item templates to make them more compatible with Silverlight 4 and to improve their visibility in Visual Studio and Expression Blend. Bug corrections When a message is sent through the Messenger class using the method Messenger.Default.Send<T>(T message, object token), and the token is a simple value (for example int), the message was not sent correctly. This bug is now corrected. New in V3 The following features have been added after V2. Sending messages with callback Certain classes have been added to the GalaSoft.MvvmLight.Messaging namespace, allowing sending a message and getting a callback from the recipient. These classes are: NotificationMessageWithCallback: Base class for messages with callback. NotificationMessageAction: A class with string notification, and a parameterless callback. NotificationMessageAction<T>: A class with string notification, and a callback with a parameter of type T. To send a message with callback, use the following code: var message = new NotificationMessageAction<bool>( "Hello world", callbackMessage => { // This is the callback code if (callbackMessage) { // ... } }); Messenger.Default.Send(message); To register and receive a message with callback, use the following code: Messenger.Default.Register<NotificationMessageAction<bool>>( this, message => { // Do something // Execute the callback message.Execute(true); }); Messenger.Default can be overriden The Messenger.Default property can also be replaced, for example for unit testing purposes, by using the Messenger.OverrideDefault method. All the public methods of the Messenger class have been made virtual, and can be overridden in the test messenger class. Sending messages to interfaces In V2, it was possible to deliver messages targeted to instances of a given class. in V3 it is still possible, but in addition you can deliver a message to instances that implement a certain interface. The message will not be delivered to other recipients. Use the overload Messenger.Default.Send<TMessage, TTarget>(TMessage message) where TTarget is, in fact, an interface (for example IDisposable). Of course the recipient must register to receive the type of message TMessage. Sending messages with a token Messages can now be sent through the Messenger with a token. To send a message with token, use the method overload Send<TMessage>(TMessage message, object token). To receive a message with token, use the methods Register<TMessage>(object recipient, object token, Action<TMessage> action) or Register<TMessage>(object recipient, object token, bool receiveDerivedMessagesToo, Action<TMessage> action) The token can be a simple value (int, string, etc…) or an instance of a class. The message is not delivered to recipients who registered with a different token, or with no token at all. Renaming CommandMessage to NotificationMessage To avoid confusion with ICommand and RelayCommand, the CommandMessage class has been renamed to NotificationMessage. This message class can be used to deliver a notification (of type string) to a recipient. ViewModelBase constructor with IMessenger The ViewModelBase class now accepts an IMessenger parameter. If this constructor is used instead of the default empty constructor, the IMessenger passed as parameter will be used to broadcast a PropertyChangedMessage when the method RaisePropertyChanged<T>(string propertyName, T oldValue, T newValue, bool broadcast) is used. In the default ViewModelBase constructor is used, the Messenger.Default instance will be used instead. EventToCommand behavior The EventToCommand behavior has been added in V3. It can be used to bind any event of any FrameworkElement to any ICommand (for example a RelayCommand located in the ViewModel). More information about the EventToCommand behavior can be found here and here. Updated the project templates to remove the sample application The project template has been updated to remove the sample application that was created every time that a new MVVM Light application was created in Visual Studio or Blend. This makes the creation of a new application easier, because you don’t need to remove code before you can start writing code. Bug corrections Some bugs that were in Version 2 have been corrected: In some occasions, an exception could be thrown when a recipient was registered for a message at the same time as a message was received. New names for DLLs If you upgrade an existing installation, you will need to change the reference to the DLLs in C:\Program Files\Laurent Bugnion (GalaSoft)\Mvvm Light Toolkit\Binaries. The assemblies have been moved, and the versions for Silverlight 4 and for WPF4 have been renamed, to avoid some confusion. It is now easier to make sure that you are using the correct DLL. WPF3.5SP1, Silverlight 3 When using the DLLs, make sure that you use the correct versions. WPF4, Silverlight 4 When using the DLLs, make sure that you use the correct versions.   Laurent Bugnion (GalaSoft) Subscribe | Twitter | Facebook | Flickr | LinkedIn

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  • WPF TabControl - how to preserve control state within tab items (MVVM pattern)

    - by Tim Coulter
    I am a newcomer to WPF, attempting to build a project that follows the recommendations of Josh Smith's excellent article describing The Model-View-ViewModel Design Pattern. Using Josh's sample code as a base, I have created a simple application that contains a number of "workspaces", each represented by a tab in a TabControl. In my application, a workspace is a document editor that allows a hierarchical document to be manipulated via a TreeView control. Although I have succeeded in opening multiple workspaces and viewing their document content in the bound TreeView control, I find that the TreeView "forgets" its state when switching between tabs. For example, if the TreeView in Tab1 is partially expanded, it will be shown as fully collapsed after switching to Tab2 and returning to Tab1. This behaviour appears to apply to all aspects of control state for all controls. After some experimentation, I have realized that I can preserve state within a TabItem by explicitly binding each control state property to a dedicated property on the underlying ViewModel. However, this seems like a lot of additional work, when I simply want all my controls to remember their state when switching between workspaces. I assume I am missing something simple, but I am not sure where to look for the answer. Any guidance would be much appreciated. Thanks, Tim Update: As requested, I will attempt to post some code that demonstrates this problem. However, since the data that underlies the TreeView is complex, I will post a simplified example that exhibits the same symtoms. Here is the XAML from the main window: <TabControl IsSynchronizedWithCurrentItem="True" ItemsSource="{Binding Path=Docs}"> <TabControl.ItemTemplate> <DataTemplate> <ContentPresenter Content="{Binding Path=Name}" /> </DataTemplate> </TabControl.ItemTemplate> <TabControl.ContentTemplate> <DataTemplate> <view:DocumentView /> </DataTemplate> </TabControl.ContentTemplate> </TabControl> The above XAML correctly binds to an ObservableCollection of DocumentViewModel, whereby each member is presented via a DocumentView. For the simplicity of this example, I have removed the TreeView (mentioned above) from the DocumentView and replaced it with a TabControl containing 3 fixed tabs: <TabControl> <TabItem Header="A" /> <TabItem Header="B" /> <TabItem Header="C" /> </TabControl> In this scenario, there is no binding between the DocumentView and the DocumentViewModel. When the code is run, the inner TabControl is unable to remember its selection when the outer TabControl is switched. However, if I explicitly bind the inner TabControl's SelectedIndex property ... <TabControl SelectedIndex="{Binding Path=SelectedDocumentIndex}"> <TabItem Header="A" /> <TabItem Header="B" /> <TabItem Header="C" /> </TabControl> ... to a corresponding dummy property on the DocumentViewModel ... public int SelecteDocumentIndex { get; set; } ... the inner tab is able to remember its selection. I understand that I can effectively solve my problem by applying this technique to every visual property of every control, but I am hoping there is a more elegant solution.

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  • MVVM Prism Nested Regions Can't Find Child Regions

    - by Garry Clark
    I have a Menu (Telerik RadMenu) that has nested regions defined in the Shell. In my modules I will register the modules menu or toolbar items with these regions. Everything works fine for the root regions, but when I try and add something to a child region, such as the File region on the Menu, I get the error "The exception message was: The region manager does not contain the FileMenuRegion region." However like I said if I change this code regionManager.Regions[RegionNames.FileMenuRegion].Add(menuItem); to this regionManager.Regions[RegionNames.MainMenuRegion].Add(menuItem); everything works fine. Below is the XAML for my menu so you can see the region names and how they are constructed. Any help would greatly be appreciated as this is bewildering and driving me crazy. Menu <telerikNavigation:RadMenu x:Name="menuMain" DockPanel.Dock="Top" prismrgn:RegionManager.RegionName="{x:Static i:RegionNames.MainMenuRegion}" telerik:StyleManager.Theme="{Binding Source={StaticResource settings}, Path=Default.CurrentTheme}"> <telerikNavigation:RadMenuItem Header="{x:Static p:Resources.File}" prismrgn:RegionManager.RegionName="{x:Static i:RegionNames.FileMenuRegion}"> <telerikNavigation:RadMenuItem Header="{x:Static p:Resources.Exit}" Command="{Binding ExitCommand}"> <telerikNavigation:RadMenuItem.Icon> <Image Source="../Resources/Close.png" Stretch="None" /> </telerikNavigation:RadMenuItem.Icon> </telerikNavigation:RadMenuItem> </telerikNavigation:RadMenuItem> </telerikNavigation:RadMenu>

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  • WPF DataContext does not refresh the DataGrid using MVVM model

    - by vikram bhatia
    Project Overview I have a view which binds to a viewmodel containing 2 ObserverableCollection. The viewmodel constructor populates the first ObserverableCollection and the view datacontext is collected to bind to it through a public property called Sites. Later the 2ed ObserverableCollection is populated in the LoadOrders method and the public property LoadFraudResults is updated for binding it with datacontext. I am using WCF to pull the data from the database and its getting pulled very nicely. VIEWMODEL SOURCE class ManageFraudOrderViewModel:ViewModelBase { #region Fields private readonly ICollectionView collectionViewSites; private readonly ICollectionView collectionView; private ObservableCollection<GeneralAdminService.Website> _sites; private ObservableCollection<FraudService.OrderQueue> _LoadFraudResults; #endregion #region Properties public ObservableCollection<GeneralAdminService.Website> Sites { get { return this._sites; } } public ObservableCollection<FraudService.OrderQueue> LoadFraudResults { get { return this._LoadFraudResults;} } #endregion public ManageFraudOrderViewModel() { //Get values from wfc service model GeneralAdminService.GeneralAdminServiceClient generalAdminServiceClient = new GeneralAdminServiceClient(); GeneralAdminService.Website[] websites = generalAdminServiceClient.GetWebsites(); //Get values from wfc service model if (websites.Length > 0) { _sites = new ObservableCollection<Wqn.Administration.UI.GeneralAdminService.Website>(); foreach (GeneralAdminService.Website website in websites) { _sites.Add((Wqn.Administration.UI.GeneralAdminService.Website)website); } this.collectionViewSites= CollectionViewSource.GetDefaultView(this._sites); } generalAdminServiceClient.Close(); } public void LoadOrders(Wqn.Administration.UI.FraudService.Website website) { //Get values from wfc service model FraudServiceClient fraudServiceClient = new FraudServiceClient(); FraudService.OrderQueue[] OrderQueue = fraudServiceClient.GetFraudOrders(website); //Get values from wfc service model if (OrderQueue.Length > 0) { _LoadFraudResults = new ObservableCollection<Wqn.Administration.UI.FraudService.OrderQueue>(); foreach (FraudService.OrderQueue orderQueue in OrderQueue) { _LoadFraudResults.Add(orderQueue); } } this.collectionViewSites= CollectionViewSource.GetDefaultView(this._LoadFraudResults); fraudServiceClient.Close(); } } VIEW SOURCE public partial class OrderQueueControl : UserControl { private ManageFraudOrderViewModel manageFraudOrderViewModel ; private OrderQueue orderQueue; private ButtonAction ButtonAction; private DispatcherTimer dispatcherTimer; public OrderQueueControl() { LoadOrderQueueForm(); } #region LoadOrderQueueForm private void LoadOrderQueueForm() { //for binding the first observablecollection manageFraudOrderViewModel = new ManageFraudOrderViewModel(); this.DataContext = manageFraudOrderViewModel; } #endregion private void cmbWebsite_SelectionChanged(object sender, SelectionChangedEventArgs e) { BindItemsSource(); } #region BindItemsSource private void BindItemsSource() { using (OverrideCursor cursor = new OverrideCursor(Cursors.Wait)) { if (!string.IsNullOrEmpty(Convert.ToString(cmbWebsite.SelectedItem))) { Wqn.Administration.UI.FraudService.Website website = (Wqn.Administration.UI.FraudService.Website)Enum.Parse(typeof(Wqn.Administration.UI.FraudService.Website),cmbWebsite.SelectedItem.ToString()); //for binding the second observablecollection******* manageFraudOrderViewModel.LoadOrders(website); this.DataContext = manageFraudOrderViewModel; //for binding the second observablecollection******* } } } #endregion } XAML ComboBox x:Name="cmbWebsite" ItemsSource="{Binding Sites}" Margin="5" Width="100" Height="25" SelectionChanged="cmbWebsite_SelectionChanged" DataGrid ItemsSource ={Binding Path = LoadFraudResults} PROBLEM AREA: When I call the LoadOrderQueueForm to bind the first observablecollection and later BindItemsSource to bind 2ed observable collection, everything works fine and no problem for the first time binding. But, when I call BindItemsSource again to repopulate the obseravablecollection based on changed selected combo value via cmbWebsite_SelectionChanged, the observalblecollection gets populated with new value and LoadFraudResults property in viewmodule is populated with new values; but when i call the datacontext to rebind the datagrid,the datagrid does not reflect the changed values. In other words the datagrid doesnot get changed when the datacontext is called the 2ed time in BindItemsSource method of the view. manageFraudOrderViewModel.LoadOrders(website); this.DataContext = manageFraudOrderViewModel; manageFraudOrderViewModel values are correct but the datagrid is not relected with changed values. Please help as I am stuck with this thing for past 2 days and the deadline is approaching near. Thanks in advance

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  • MVVM pattern and nested view models - communication and lookup lists

    - by LostInWPF
    I am using Prism for a new application that I am creating. There are several lookup lists that will be used in several places in the application. Therefore it makes sense to define it once and use that everywhere I need that functionality. My current solution is to use typed data templates to render the controls inside a content control. <DataTemplate DataType={x:Type ListOfCountriesViewModel}> <ComboBox ItemsSource={Binding Countries} SelectedItem="{Binding SelectedCountry"/> </DataTemplate> <DataTemplate DataType={x:Type ListOfRegionsViewModel}> <ComboBox ItemsSource={Binding Countries} SelectedItem={Binding SelectedRegion} /> </DataTemplate> public class ParentViewModel { SelectedCountry get; set; SelectedRegion get; set; ListOfCountriesViewModel CountriesVM; ListOfRegionsViewModel RgnsVM; } Then in my window I have 2 content controls and the rest of the controls <ContentControl Content="{Binding CountriesVM}"></ContentControl> <ContentControl Content="{Binding RgnsVM}"></ContentControl> <Rest of controls on view> At the moment I have this working and the SelectedItems for the combo boxes are publising events via EventAggregator from the child view models which are then subscribed to in the parent view model. I am not sure that this is the best way to go as I can imagine I would end up with a lot of events very quickly and it will become unwieldy. Also if I was to use the same view model on another window it will publish the event and this parent viewmodel is subscribed to it which could have unintended consequences. My questions are :- Is this the best way to put lookup lists in a view which can be re-used across screens? How do I make it so that the combobox which is bound to the child viewmodel sets the relevant property on the parent viewmodel without using events / mediator. e.g in this case SelectedCountry for example? Any alternative implementation proposals for what I am trying to do? I have a feeling I am missing something obvious and there is so much info it is hard to know what is right so any help would be most gratefully received.

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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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  • ItemsControl.ItemsSource MVVM performance

    - by bitbonk
    I have an (non-virtualized) ItemsControl that binds its ItemsSource to a ObeservableCollection of ViewModel instances. Now once the large amount Model instances is loaded all the ViewModel complemnents needs to be added to that ObservableCollection. How can I add a large amount of ViewModels without making the UI Thread hang? I suppose the UI Thread hangs because each time a new item is added the ItemsControl needs to update itself and does layout etc. over and over again. Should I suspend the binding add all items and then resume? If so, how? Should I override the ObservableCollection to implement an AddRange so only 1 CollectionChanged Event is fired for adding multiple items? Or alternatively just replace the whole collection? Or is it better to add each items separately and call Dispatcher.Invoke for each item separately? So I would unblock frequently. How do you handle large dynamic lists that can not be virtualized?

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  • MVVM - ListBox SelectedItem Binding Property Going Null

    - by Peanut
    So i have a listbox: <ListBox x:Name="listbox" HorizontalAlignment="Left" Margin="8,8,0,8" Width="272" BorderBrush="{x:Null}" Background="{x:Null}" Foreground="{x:Null}" ItemsSource="{Binding MenuItems}" ItemTemplate="{DynamicResource MenuItemsTemplate}" SelectionChanged="ListBox_SelectionChanged" SelectedItem="{Binding SelectedItem}"> </ListBox> and i have this included in my viewmodel: public ObservableCollection<MenuItem> MenuItems { get { return menuitems; } set { menuitems = value; NotifyPropertyChanged("MenuItems"); } } public MenuItem SelectedItem { get { return selecteditem; } set { selecteditem = value; NotifyPropertyChanged("SelectedItem"); } } and also in my viewmodel: public void UpdateStyle() { ActiveHighlight = SelectedItem.HighlightColor; ActiveShadow = SelectedItem.ShadowColor; } So, the objective is to call UpdateStyle() whenever selectedchanged event is fired. So in the .CS file, i call UpdateStyle(). The problem is, whenever I get into the selectionchanged event method, my ViewModel.SelectedItem is always null. I tried debugging this to see if the binding was working correctly, and it is. When I click on an item in the listbox, the SelectedItem Set is triggered, setting the value... but somewhere inbetween that and the selected changed (In the CS File) It gets reset to Null. Can anyone help out? Thanks

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  • MVVM && IOC && Sub-ViewModels

    - by Lee Treveil
    I have a ViewModel, it takes two parameters in the constructor that are of the same type: public class CustomerComparerViewModel { public CustomerComparerViewModel(CustomerViewModel customerViewModel1, CustomerViewModel customerViewModel2) { } } public class CustomerViewModel { public string FirstName { get; set; } public string LastName { get; set; } } If I wasn't using IOC I could just new up the viewmodel and pass the sub-viewmodels in. I could package the two viewmodels into one class and pass that into the constructor but if I had another viewmodel that only needed one CustomerViewModel I would need to pass in something that the viewmodel does not need. How do I go about dealing with this using IOC? I'm using Ninject btw. Thanks

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  • ItemsControl.ItemsSource MVVM perormance

    - by bitbonk
    I have an (non-virtualized) ItemsControl that binds its ItemsSource to a ObeservableCollection of ViewModel instances. Now once the large amount Model instances is loaded all the ViewModel complemnents needs to be added to that ObservableCollection. How can I add a large amount of ViewModels without making the UI Thread hang? I suppose the UI Thread hangs because each time a new item is added the ItemsControl needs to update itself and does layout etc. over and over again. Should I suspend the binding add all items and then resume? If so, how? Should I override the ObservableCollection to implement an AddRange so only 1 CollectionChanged Event is fired for adding multiple items? Or alternatively just replace the whole collection? Or is it better to add each items separately and call Dispatcher.Invoke for each item separately? So I would unblock frequently. How do you handle large dynamic lists that can not be virtualized?

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