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  • Disable Adding Item to Collection

    - by Wonko the Sane
    Hi All, I'm sure there's an "easy" answer to this, but for the moment it escapes me. In an MVVM application, I have a property that is a ObservableCollection, used for displaying some set of elements on the view. private readonly ObservableCollection<MyType> mMyCollection = new ObservableCollection<MyType>(); public ObservableCollection<MyType> MyCollection { get { return mMyCollection; } } I want to restrict consumers of this collection from simply using the property to add to the collection (i.e. I want to prevent this from the view): viewModel.MyCollection.Add(newThing); // want to prevent this! Instead, I want to force the use of a method to add items, because there may be another thread using that collection, and I don't want to modify the collection while that thread is processing it. public void AddToMyCollection(MyType newItem) { // Do some thread/task stuff here } Thanks, wTs

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  • Validation of WPF User Input using MVVM and Entity Framework 4.0

    - by Emad
    I am building a WPF 4.0 Application using MVVM. The Model is generated using Entity Framework 4.0. I am using Data binding on the WPF to bind the user input to model properties. What is the easiest way to validate user input ? I prefer an approach where I can set the validation rules on the Model rather than on the WPF itself. How can this be done? Any samples are appreciated.

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  • Passing a parameter using RelayCommand defined in the ViewModel (from Josh Smith example)

    - by eesh
    I would like to pass a parameter defined in the XAML (View) of my application to the ViewModel class by using the RelayCommand. I followed Josh Smith's excellent article on MVVM and have implemented the following. XAML Code <Button Command="{Binding Path=ACommandWithAParameter}" CommandParameter="Orange" HorizontalAlignment="Left" Style="{DynamicResource SimpleButton}" VerticalAlignment="Top" Content="Button"/> ViewModel Code public RelayCommand _aCommandWithAParameter; /// <summary> /// Returns a command with a parameter /// </summary> public RelayCommand ACommandWithAParameter { get { if (_aCommandWithAParameter == null) { _aCommandWithAParameter = new RelayCommand( param => this.CommandWithAParameter("Apple") ); } return _aCommandWithAParameter; } } public void CommandWithAParameter(String aParameter) { String theParameter = aParameter; } #endregion I set a breakpoint in the CommandWithAParameter method and observed that aParameter was set to "Apple", and not "Orange". This seems obvious as the method CommandWithAParameter is being called with the literal String "Apple". However, looking up the execution stack, I can see that "Orange", the CommandParameter I set in the XAML is the parameter value for RelayCommand implemenation of the ICommand Execute interface method. That is the value of parameter in the method below of the execution stack is "Orange", public void Execute(object parameter) { _execute(parameter); } What I am trying to figure out is how to create the RelayCommand ACommandWithAParameter property such that it can call the CommandWithAParameter method with the CommandParameter "Orange" defined in the XAML. Is there a way to do this? Why do I want to do this? Part of "On The Fly Localization" In my particular implementation I want to create a SetLanguage RelayCommand that can be bound to multiple buttons. I would like to pass the two character language identifier ("en", "es", "ja", etc) as the CommandParameter and have that be defined for each "set language" button defined in the XAML. I want to avoid having to create a SetLanguageToXXX command for each language supporting and hard coding the two character language identifier into each RelayCommand in the ViewModel.

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  • MVC2 DataAnnotations on ViewModel - ModelState.isValid Always Returns true

    - by ScottSEA
    I have an MVC2 Application that uses MVVM pattern. I am trying use Data Annotations to validate form input. In my ThingsController I have two methods: [HttpGet] public ActionResult Index() { return View(); } public ActionResult Details(ThingsViewModel tvm) { if (!ModelState.IsValid) return View(tvm); try { Query q = new Query(tvm.Query); ThingRepository repository = new ThingRepository(q); tvm.Airplanes = repository.All(); return View(tvm); } catch (Exception) { return View(); } } My Details.aspx view is strongly typed to the ThingsViewModel: <%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<Config.Web.Models.ThingsViewModel>" %> The ViewModel is a class consisting of a IList of returned Thing objects and the Query string (which is submitted on the form) and has the Required data annotation: public class ThingsViewModel { public IList<Thing> Things{ get; set; } [Required(ErrorMessage="You must enter a query")] public string Query { get; set; } } When I run this, and click the submit button on the form without entering a value I get a YSOD with the following error: The model item passed into the dictionary is of type 'Config.Web.Models.ThingsViewModel', but this dictionary requires a model item of type System.Collections.Generic.IEnumerable`1[Config.Domain.Entities.Thing]'. How can I get Data Annotations to work with a ViewModel? I cannot see what I'm missing or where I'm going wrong - the VM was working just fine before I started mucking around with validation.

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  • How create a Firefox-like search textbox in WPF?

    - by Simon
    Hey there. I'm writing an application in WPF using the MVVM-pattern and will really often use TextBoxes. I don't want to use labels for the user to know user what the text box is for, i.e. I don't want something like this: <TextBlock> Name: </TextBlock> <TextBox /> Instead, I would like the TextBox to contain its own label. Statically, you would express it like this: <TextBox>Name</TextBox> If the cursor is displayed in the textbox, i.e. the TextBox gains focus, I want the description text to disappear. If the TextBox is left empty and it loses the focus, the description text should be shown again. It's similar to the search textbox of StackOverflow or the one of Firefox. (please tell me if your not sure what I mean). One TextBox's label may change at runtime, dependending on e.g. a ComboBox's selected element or a value in my ViewModel. (It's like in Firefox's search TextBox, if you select google from the search engins' menu, the TextBox's label changes to "Google", if you select "Yahoo" its set to "Yahoo"). Thus I want to be able to bind the label's content. Consider that I may already have a Binding on the Text-Property of the TextBox. How can implement such a behaviour and make it reusable for any of my TextBox's? Code is welcome but not needed; a description of what to do is enough. Thank you in advance.

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  • How to achieve "Blendability" when using DataServiceCollection in my ViewModel

    - by andlju
    I'm looking at using oData endpoints in my Silverlight client. Naturally, I'm doing MVVM and I want the project to be nice and "Blendable" (i.e. I must be able to cleanly use static data instead of the oData endpoints when in design mode.) Now to the problem. I'd like to use the DataServiceCollection in my ViewModels, since it allows for nice bindable collections without having to worry too much with BeginExecute/EndExecute etc. Now, let's look at some code. My Model interface looks like this: public interface ITasksModel { IQueryable<Task> Tasks { get; } } The oData endpoint implementation of that interface: public class TasksModel : ITasksModel { Uri svcUri = new Uri("http://localhost:2404/Services/TasksDataService.svc"); TaskModelContainer _container; public TasksModel() { _container = new TaskModelContainer(svcUri); } public IQueryable<Task> Tasks { get { return _container.TaskSet; } } } And the "Blendable" design-time implementation: public class DesignModeTasksModel : ITasksModel { private List<Task> _taskCollection = new List<Task>(); public DesignModeTasksModel() { _taskCollection.Add(new Task() { Id = 1, Title = "Task 1" }); _taskCollection.Add(new Task() { Id = 2, Title = "Task 2" }); _taskCollection.Add(new Task() { Id = 3, Title = "Task 3" }); } public IQueryable<Task> Tasks { get { return _taskCollection.AsQueryable(); } } } However, when I try to use this last one in my ViewModel constructor: public TaskListViewModel(ITasksModel tasksModel) { _tasksModel = tasksModel; _tasks = new DataServiceCollection<Task>(); _tasks.LoadAsync(_tasksModel.Tasks); } I get an exception: Only a typed DataServiceQuery object can be supplied when calling the LoadAsync method on DataServiceCollection. First of all, if this is the case, why not make the input parameter of LoadAsync be typed as DataServiceQuery? Second, what is the "proper" way of doing what I'm trying to accomplish?

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  • LINQ to Entities exceptions (ElementAtOrDefault and CompareObjectEqual)

    - by OffApps Cory
    I am working on a shipping platform which will eventually automate shipping through several major carriers. I have a ShipmentsView Usercontrol which displayes a list of Shipments (returned by EntityFramework), and when a user clicks on a shipment item, it spawns a ShipmentEditView and passes the ShipmentID (RecordKey) to that view. I initially wrestled with trying to get the context from the parent (ShipmentsView) and finally gave up resolving to get to it later. I wanted to do this to keep a single instance of the context. anyhow, I now create a new instance of the context in my ShipmentEditViewModel, and query against it for the Shipment record. I know I could just pass the record, but I wanted to use the Ocean Framework that Karl Shifflett wrote and don't want to muck about writing new transition methods. So anyhow, I query and when stepping through, I can see that it returns a record, as soon as execution reached the point where it assigned the query result to the e.Result property, it throws up the following exception depending on the query I used. LINQToEntities Dim RecordID As Decimal = CDec(e.Argument) Dim myResult = From ship In _Context.Shipment _ Where ship.ShipID = e.Argument _ Select ship Select Case myResult.Count Case 0 e.Result = New Shipment Case 1 e.Result = myResult(0) Case Else e.Result = Nothing End Select "LINQ to Entities does not recognize the method 'System.Object.CompareObjectEqual(System.Object, System.Object, Boolean)' method, and this method cannot be translated into a store expression. LINQToEntities via Method calls Dim RecordID As Decimal = CDec(e.Argument) Dim myResult = _Context.Shipment.Where(Function(s) s.ShipID = RecordID) Select Case myResult.Count Case 0 e.Result = New Shipment Case 1 e.Result = myResult(0) Case Else e.Result = Nothing End Select LINQ to Entities does not recognize the method 'SnazzyShippingDAL.Shipment ElementAtOrDefault[Shipment] (System.Linq.IQueryable`1[SnazzyShippingDAL.Shipment], Int32)' method, and this method cannot be translated into a store expression. I have been trying to get this thing to display a record for like three days. i am seriously thinking about going back and re=-engineering it without the MVVM pattern (which I realize I am only starting to learn and understand) if only to make the &$^%ed thing work. Any help will be muchly appreciated. Cory

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  • how to create and track multiple pairs "View-ViewModel"?

    - by Gianluca Colucci
    Hi! I am building an application that is based on MVVM-Light. I am in the need of creating multiple instances of the same View, and each one should bind to its own ViewModel. The default ViewModelLocator implements ViewModels as singletons, therefore different instances of the same View will bind to the same ViewModel. I could create the ViewModel in the VMLocator as a non-static object (as simple as returning new VM()...), but that would only partially help me. In fact, I still need to keep track of the opened windows. Nevertheless, each window might open several other windows (of a different kind, though). In this situation I might need to execute some operation on the parent View and all its children. For example before closing the View P, I might want to close all its children (view C1, view C2, etc.). Hence, is there any simple and easy way to achieve this? Or is there any best practice you would advice me to follow? Thanks in advance for your precious help. Cheers, Gianluca.

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  • Binding to WPF ViewModel properties

    - by MartinHN
    I'm just playing around with WPF and MVVM, and I have made a simple app that displays a Rectangle that changes color whenever Network availability changes. But when that happens, I get this error: Cannot use a DependencyObject that belongs to a different thread than its parent Freezable. Code XAML <Window x:Class="WpfApplication1.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="Window1" Height="400" Width="600"> <DockPanel LastChildFill="True"> <Rectangle x:Name="networkStatusRectangle" Width="200" Height="200" Fill="{Binding NetworkStatusColor}" /> </DockPanel> </Window> Code-behind using System.Windows; using WpfApplication1.ViewModels; namespace WpfApplication1 { /// <summary> /// Interaction logic for Window1.xaml /// </summary> public partial class Window1 : Window { public Window1() { InitializeComponent(); DataContext = new NetworkViewModel(); } } } ViewModel using System.ComponentModel; using System.Net.NetworkInformation; using System.Windows.Media; namespace WpfApplication1.ViewModels { public class NetworkViewModel : INotifyPropertyChanged { private Brush _NetworkStatusColor; public Brush NetworkStatusColor { get { return _NetworkStatusColor; } set { _NetworkStatusColor = value; NotifyOfPropertyChange("NetworkStatusColor"); } } public NetworkViewModel() { NetworkChange.NetworkAvailabilityChanged += new NetworkAvailabilityChangedEventHandler(NetworkChange_NetworkAvailabilityChanged); } protected void NetworkChange_NetworkAvailabilityChanged(object sender, NetworkAvailabilityEventArgs e) { if (e.IsAvailable) { this.NetworkStatusColor = new SolidColorBrush(Colors.Green); } else { this.NetworkStatusColor = new SolidColorBrush(Colors.Red); } } public event PropertyChangedEventHandler PropertyChanged = delegate { }; public void NotifyOfPropertyChange(string propertyName) { PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); } } } I assume that I should change the NetworkStatusColor property by invoking something?

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  • RelayCommand sender from ItemsControl item

    - by Padu Merloti
    I've been using MVVM's RelayCommand with success to bind actions to XAML, but I'm having a small problem with my ItemsControl. <ItemsControl ItemsSource="{Binding Devices}" > <ItemsControl.ItemTemplate> <DataTemplate> <Grid Width="100" Margin="4" > <Button Command="{Binding Path=SelectDeviceCommand}" > <Grid> <Image Source="img_small.png"></Image> <Image Source="{Binding Path=Logo}" /> </Grid> </Button> </Grid> </DataTemplate> </ItemsControl.ItemTemplate> </ItemsControl> In my view model: public RelayCommand SelectDeviceCommand { get; set; } private ObservableCollection<Device> Devices; Devices = CreateListOfDevices(); private void InitializeCommands() { SelectDeviceCommand = new RelayCommand((s) => MessageBox.Show(s.ToString())); } How do I define my SelectDeviceCommand in my view model in order to receive object that is bound to that item? My SelectDeviceCommand is not even being called... (but that I guess is because I need to make my Device a mini-viewmodel and implement the SelectDeviceCommand in it, is that correct?)

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  • Get the value for a WPF binding

    - by Jose
    Ok, I didn't want a bunch of ICommands in my MVVM ViewModels so I decided to create a MarkupExtension for WPF that you feed it a string(the name of the method), and it gives you back an ICommand that executes the method. here's a snippet: public class MethodCall : MarkupExtension { public MethodCall(string methodName) { MethodName = methodName; CanExecute = "Can" + methodName; } public override object ProvideValue(IServiceProvider serviceProvider) { Binding bin= new Binding { Converter = new MethodConverter(MethodName,CanExecute) }; return bin.ProvideValue(serviceProvider); } } public class MethodConverter : IValueConverter { string MethodName; public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { //Convert to ICommand ICommand cmd = ConvertToICommand(); if (cmd == null) Debug.WriteLine(string.Format("Could not bind to method 'MyMethod' on object",MethodName)); return cmd; } } It works great, except when the binding fails(e.g. you mistype). When you do this in xaml: {Binding MyPropertyName} you see in the output window whenever the binding fails. and it tells you the propertyName the Type name etc. The MethodConverter Class can tell you the name of the method that failed, but it can't tell you the source object type. Because the value will be null. I can't figure out how to store the source object type so for the following class public class MyClass { public void MyMethod() { } } and the following xaml: <Button Command={d:MethodCall MyMethod}>My Method</Button> It currently says: "Could not bind to method 'MyMethod' on object but I would like it to say: "Could not bind to method 'MyMethod' on object MyClass Any ideas?

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  • ViewModel updates after Model server roundtrip

    - by Pavel Savara
    I have stateless services and anemic domain objects on server side. Model between server and client is POCO DTO. The client should become MVVM. The model could be graph of about 100 instances of 20 different classes. The client editor contains diverse tab-pages all of them live-connected to model/viewmodel. My problem is how to propagate changes after server round-trip nice way. It's quite easy to propagate changes from ViewModel to DTO. For way back it would be possible to throw away old DTO and replace it whole with new one, but it will cause lot of redrawing for lists/DataTemplates. I could gather the server side changes and transmit them to client side. But the names of fields changed would be domain/DTO specific, not ViewModel specific. And the mapping seems nontrivial to me. If I should do it imperative way after round-trip, it would break SOC/modularity of viewModels. I'm thinking about some kind of mapping rule engine, something like automappper or emit mapper. But it solves just very plain use-cases. I don't see how it would map/propagate/convert adding items to list or removal. How to identify instances in collections so it could merge values to existing instances. As well it should propagate validation/error info. Maybe I should implement INotifyPropertyChanged on DTO and try to replay server side events on it ? And then bind ViewModel to it ? Would binding solve the problems with collection merges nice way ? Is EventAgregator from PRISM useful for that ? Is there any event record-replay component ? Is there better client side pattern for architecture with server side logic ?

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  • MVVM- How can I bind to a property, which is not a DependancyProperty?

    - by highone
    I have found this question http://stackoverflow.com/questions/2245928/mvvm-and-the-textboxs-selectedtext-property. However, I am having trouble getting the solution given to work. This is my non-working code: View: SelectedText and Text are just string properties from my ViewModel. <TextBox Text="{Binding Path=Text, UpdateSourceTrigger=PropertyChanged}" Height="155" HorizontalAlignment="Left" Margin="68,31,0,0" Name="textBox1" VerticalAlignment="Top" Width="264" AcceptsReturn="True" AcceptsTab="True" local:TextBoxHelper.SelectedText="{Binding SelectedText, UpdateSourceTrigger=PropertyChanged}" /> <TextBox Text="{Binding SelectedText, Mode=OneWay, UpdateSourceTrigger=PropertyChanged}" Height="154" HorizontalAlignment="Left" Margin="82,287,0,0" Name="textBox2" VerticalAlignment="Top" Width="239" /> TextBoxHelper public static class TextBoxHelper { #region "Selected Text" public static string GetSelectedText(DependencyObject obj) { return (string)obj.GetValue(SelectedTextProperty); } public static void SetSelectedText(DependencyObject obj, string value) { obj.SetValue(SelectedTextProperty, value); } // Using a DependencyProperty as the backing store for SelectedText. This enables animation, styling, binding, etc... public static readonly DependencyProperty SelectedTextProperty = DependencyProperty.RegisterAttached( "SelectedText", typeof(string), typeof(TextBoxHelper), new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, SelectedTextChanged)); private static void SelectedTextChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e) { TextBox tb = obj as TextBox; if (tb != null) { if (e.OldValue == null && e.NewValue != null) { tb.SelectionChanged += tb_SelectionChanged; } else if (e.OldValue != null && e.NewValue == null) { tb.SelectionChanged -= tb_SelectionChanged; } string newValue = e.NewValue as string; if (newValue != null && newValue != tb.SelectedText) { tb.SelectedText = newValue as string; } } } static void tb_SelectionChanged(object sender, RoutedEventArgs e) { TextBox tb = sender as TextBox; if (tb != null) { SetSelectedText(tb, tb.SelectedText); } } #endregion } What am I doing wrong?

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  • TextBox should display text in hexadecimal in a specific format

    - by Owais Wani
    I have a textbox in my xaml file which is editable. Now according to my project requirements content in textbox should only be 0-9 and a-f (hexadecimal values) and textbox should take the input based on hexadecimal values. Demonstratation: 12 ab 32 a5 64 Now if my cursor is at the end and i go on pressing backspace, it shud remove the values as it happens in a general text box. Now If my cursor is at the beginning of a5, and i press "delete key", the value should become like: 12 ab 32 56 4 If my cursor is at the end of a5 and i press the 'delete key" nothing should happen. I had done this successful in my C++ application as follows: void CMSP430CommPanel::textEditorTextChanged (TextEditor& editor) { if(&editor == m_texti2cWrite) { int count = 0; int location; String text1 = m_texti2cWrite->getText(); String text = m_texti2cWrite->getText().removeCharacters(" "); String hexString = String::empty; int countCaret = m_texti2cWrite->getCaretPosition(); for(int i=0; i < text.length(); i++) { hexString = hexString + String (&text[i], 1); if((i+1) % 2 == 0) { if(i != text.length()-1) { hexString = hexString + T(" "); count ++; } } count ++; } m_texti2cWrite->setText(hexString,false); if(text1.length() == m_texti2cWrite->getCaretPosition()) { m_texti2cWrite->setCaretPosition(count); } else { m_texti2cWrite->setCaretPosition(countCaret); } } } where m_texti2cWrite is the name given to textbox. How can i implement the same case in my wpf application which is MVVM based. I have a textbox which shud take inputs as I said above. please help!!!

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  • Where to Store ID Field In Silverlight

    - by Blake Blackwell
    I am trying to use the MVVM pattern, and I am wondering where I place an ID value. Do I create a TextBlock that has its visibility property set to collapsed? Or is there a better place to store this kind of data? Currently the command parameter is set to: CommandParameter="{Binding ElementName=Name,Path=Text}" But I'd rather it be something like: CommandParameter="{Binding ElementName=Id,Path=Text}" I'm totally up for suggestions on what the best way there is to do this, since I'm new to this pattern and presentation language. <ListBox x:Name="MyListBox" ItemsSource="{Binding MyData, Mode=TwoWay}" BorderThickness="0"> <ListBox.ItemTemplate> <DataTemplate> <StackPanel Orientation="Horizontal"> <CheckBox x:Name="Visible" IsChecked="{Binding Visible, Mode=TwoWay}" Command="{Binding ElementName=MyListBox, Path=DataContext.MyCommand}" CommandParameter="{Binding ElementName=Name,Path=Text}" /> <TextBlock Text="{Binding Name}" /> </StackPanel> </DataTemplate> </ListBox.ItemTemplate> </ListBox> EDIT: Option 1 <CheckBox x:Name="Visible" IsChecked="{Binding Visible, Mode=TwoWay}" Command="{Binding ElementName=MyListBox, Path=DataContext.MyCommand}" CommandParameter="{Binding Id}" /> This option gives me just the Id, which is useful in many situations. EDIT: Option 2 <CheckBox x:Name="Visible" IsChecked="{Binding Visible, Mode=TwoWay}" Command="{Binding ElementName=MyListBox, Path=DataContext.MyCommand}" CommandParameter="{Binding}" /> This option gives me the full model, which is even useful for my particular situation.

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  • How do I stop ValueConverters from firing when swapping the content of a ContentControl

    - by DanM
    I thought what I was doing was right out of the Josh Smith MVVM handbook, but I seem to be having a lot of problems with value converters firing when no data in the view-model has changed. So, I have a ContentControl defined in XAML like this: <ContentControl Grid.Row="0" Content="{Binding CurrentViewModel}" /> The Window containing this ContentControl references a resource dictionary that looks something like this: <ResourceDictionary ...> <DataTemplate DataType="{x:Type lib_vm:SetupPanelViewModel}"> <lib_v:SetupPanel /> </DataTemplate> <DataTemplate DataType="{x:Type lib_vm:InstructionsPanelViewModel}"> <lib_v:InstructionsPanel /> </DataTemplate> </ResourceDictionary> So, basically, the two data templates specify which view to show with which view-model. This switches the views as expected whenever the CurrentViewModel property on my window's view-model changes, but it also seems to cause value converters on the views to fire even when no data has changed. It's a particular problem with IMultiValueConverter classes, because the values in the value array get set to DependencyProperty.UnsetValue, which causes exceptions unless I specifically check for that. But I'm getting other weird side effects too. This has me wondering if I shouldn't just do everything manually, like this: Instantiate each view. Set the DataContext of each view to the appropriate view-model. Give the ContentControl a name and make it public. Handle the PropertyChanged event for the window. In the event handler, manually set the Content property of the ContentControl to the appropriate view, based the CurrentViewModel (using if statements). This seems to work, but it also seems very inelegant. I'm hoping there's a better way. Could you please advise me the best way to handle view switching so that value converters don't fire unnecessarily?

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  • How do you pass a BitmapImage from a background thread to the UI thread in WPF?

    - by DanM
    I have a background thread that generates a series of BitmapImage objects. Each time the background thread finishes generating a bitmap, I would like to show this bitmap to the user. The problem is figuring out how to pass the BitmapImage from the background thread to the UI thread. This is an MVVM project, so my view has an Image element: <Image Source="{Binding GeneratedImage}" /> My view-model has a property GeneratedImage: private BitmapImage _generatedImage; public BitmapImage GeneratedImage { get { return _generatedImage; } set { if (value == _generatedImage) return; _generatedImage= value; RaisePropertyChanged("GeneratedImage"); } } My view-model also has the code that creates the background thread: public void InitiateGenerateImages(List<Coordinate> coordinates) { ThreadStart generatorThreadStarter = delegate { GenerateImages(coordinates); }; var generatorThread = new Thread(generatorThreadStarter); generatorThread.ApartmentState = ApartmentState.STA; generatorThread.IsBackground = true; generatorThread.Start(); } private void GenerateImages(List<Coordinate> coordinates) { foreach (var coordinate in coordinates) { var backgroundThreadImage = GenerateImage(coordinate); // I'm stuck here...how do I pass this to the UI thread? } } I'd like to somehow pass backgroundThreadImage to the UI thread, where it will become uiThreadImage, then set GeneratedImage = uiThreadImage so the view can update. I've looked at some examples dealing with the WPF Dispatcher, but I can't seem to come up with an example that addresses this issue. Please advise.

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  • How to tell which dataform button ended edit when using EventToCommand

    - by Rodd
    I'm new to SilverLight and Mvvm-Light. I have a DataForm on my view that displays/edits a SelectedPerson property (a Person object) of my view model. I want to execute a command on my viewmodel when the user clicks the Save button but don't want to take action if the user clicks cancel. I added the following to my ViewModel: public RelayCommand PersonEditEnded {get; set;} ... public void Initialize() { PersonEditEnded = new RelayCommand(DoSomething); ... } public void DoSomething() { } I added the following to my View: <toolkit:DataForm x:Name="PersonForm" ... CurrentItem="{Binding SelectedPerson, Mode=TwoWay}"> <i:Interaction.Triggers> <i:EventTrigger EventName="EditEnded"> <gs:EventToCommand Command="{Binding PersonEditEnded, Mode=OneWay}"/> </i:EventTrigger> </i:Interaction.Triggers> </toolkit:DataForm> This works and the DoSomething method is being called when the user presses Submit. However, DoSomething is also called when user presses Cancel. Is there a way to know which button was pressed or to supress the call when Cancel is pressed? Thanks for whatever help you can offer!

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  • Validation L2S question

    - by user158020
    This may be a bit winded because I am new to wpf. I have created a partial class for an entity in my L2S class that is primarily used for validation. It implements the onchanging and onvalidate methods. I am trying to use the MVVM pattern, and in a window/view I have set the datacontext in the xaml: <Window.DataContext> <vm:StartViewModel /> </Window.DataContext> when a user leaves a required field in the view blank, the onchanging event of the partial class is fired when I close the form, not when I save the data. So, if a user leaves the textbox blank, the old value is retained and the onchaging method is fired, but I have no idea how to alert the user of the resulting error. here is my onchanging code in the partial class: partial void Ondocument_titleChanging(string value) { if (value.Length == 0) throw new Exception("Document title is required."); if (value.Length > 256) throw new Exception("Document title cannot be longer than 256 characters."); } throwing an exception doesn't notify the user of the error. it just allows the form to close and rejects the changes to the textbox. hope this makes sense... edit: this example was taken from Scott Guthries article here: http://aspalliance.com/1427_LINQ_to_SQL_Part_5__Binding_UI_using_the_ASPLinqDataSource_Control.5

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  • Set form MinWidth and MinHeight based on child property

    - by Jon Mitchell
    I'm writing an application in WPF using the MVVM pattern. In my application I've got an IPopupWindowService which I use to create a popup dialog window. So to show a ViewModel in a popup window you'd do something like this: var container = ServiceLocator.Current.GetInstance<IUnityContainer>(); var popupService = container.Resolve<IPopupWindowService>(); var myViewModel = container.Resolve<IMyViewModel>(); popupService.Show((ViewModelBase)myViewModel); This is all well and good. What I want to do is be able to set the MinHeight and MinWidth on the View bound to myViewModel and have the popup window use those settings so that a user cannot make the window smaller than its contents will allow. At the moment when the user shrinks the window the contents stops resizing but the window doesn't. EDIT: I map my Views to my ViewModels in ResourceDictionarys like so: <DataTemplate DataType="{x:Type ViewModels:MyViewModel}"> <Views:MyView /> </DataTemplate> And my popup view looks like this: <Window x:Class="TheCompany.Cubit.Shell.Views.PopupWindowView" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" SizeToContent="WidthAndHeight" WindowStartupLocation="CenterOwner"> <DockPanel x:Name="panelContent"> <StackPanel HorizontalAlignment="Right" DockPanel.Dock="Bottom" Orientation="Horizontal" Visibility="{Binding RelativeSource={RelativeSource AncestorType=Window},Path=ButtonPanelVisibility}"> <Button Width="75" IsDefault="True" x:Uid="ViewDialog_AcceptButton" Click="OnAcceptButtonClick" Margin="4">OK</Button> <Button Width="75" IsCancel="True" x:Uid="ViewDialog_CancelButton" Click="OnCancelButtonClick" Margin="0,4,4,4">Cancel</Button> </StackPanel> <ContentPresenter Content="{Binding}" /> </DockPanel>

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  • How can I change the visibility of elements inside a DataTemplate when a row is selected in a Silver

    - by miketrash
    I'm using the MVVM pattern. I've bound my items and I want to only show the edit button when a row is selected in the datagrid. It appears to be possible with triggers in WPF but we don't have triggers in Silverlight. I tried a TemplatedParent binding but I'm not sure what the TemplatedParent is in this case. We don't have RelativeSource ancestor in Silverlight either. At this point I'm going to look at a solution using the code behind... <data:DataGrid.Columns> <data:DataGridTemplateColumn IsReadOnly="True" Header="Name" Width="300"> <data:DataGridTemplateColumn.CellTemplate> <DataTemplate> <Grid> <TextBlock x:Name="textBlock" Text="{Binding Name, Mode=OneWay}" VerticalAlignment="Center" Margin="4,4,0,4"/> <Button Margin="1,1,4,1" HorizontalAlignment="Right" VerticalAlignment="Center" Padding="7,4" Content="Edit" /> </Grid> </DataTemplate> </data:DataGridTemplateColumn.CellTemplate> </data:DataGridTemplateColumn> </data:DataGrid.Columns>

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  • Regarding the ViewModel

    - by mizipzor
    Im struggling to understand the ViewModel part of the MVVM pattern. My current approach is to have a class, with no logic whatsoever (important), except that it implements INotifyPropertyChanged. The class is just a collection of properties, a struct if you like, describing an as small part of the data as possible. I consider this my Model. Most of the WPF code I write are settings dialogs that configure said Model. The code-behind of the dialog exposes a property which returns an instance of the Model. In the XAML code I bind to subproperties of that property, thereby binding directly to the Model's properties. Which works quite well since it implements the INotifyPropertyChanged. I consider this settings dialog the View. However, I havent really been able to figure out what in all this is the ViewModel. The articles Ive read suggests that the ViewModel should tie the View and the Model together, providing the logic the Model lacks but is still to complex to go directly into the View. Is this correct? Would, in my example, the code-behind of the settings dialog be considered the ViewModel? I just feel a bit lost and would like my peers to debunk some of my assumptions. Am I completely off track here?

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  • Avoiding mass propagation of properties and events for exposure to ViewModels.

    - by firoso
    I have an MVVM application I am developing that is to the point where I'm ready to start putting together a user interface (my client code is largely functional) I'm now running into the issue that I'm trying to get my application data to where I need it so that it can be consumed by the view model and then bound to the view. Unfortunately, it seems that I've either got a few structural oversights, or I'm just going to have to face the reality that I need to be propogating events and raising excessive amounts of errors to notify view models that thier properties have changed. Let me go into some examples of my issue: I have a class "Unit" contained in a class "Test", contained in a class "Session" contained in a class "TestManager" which is contained in "TestDataModel" which is utilized by "TestViewModel" which is databound to by my "TestView" .... WHOA. Now, consider that Unit (the bottom of the heiarchy) has a property called "Results" that is updated periodically, I want to expose that to my viewmodel and then databind it to my view, trouble is, the only way I can really think to do this is to perpetuate events WAY up a chain that say "I've been updated!" and then request the new value... This seems like an aweful way to do this. Alternatively, I could register a static event and raise it, and have the appropriate "Unit view model" grab the event and request the update. This SEEMS better... but... static events? Is that a taboo idea? Also, having an expression like: TestDataModel.TestManager.Session.Test.Unit.Results[i] Seems REALLY gross to have on a View Model. I know this all reeks of a bad design issue, but I can't figure out what I did wrong? Should I be using more singleton/container controlled lifetimes type objects? Register object instances with static helper containers? Obviously these are hard questions to answer without being intimate with the existing structure, but if you've run into situations like this, what did you do to refactor? Should I just live with this, add mass events, and propogate them?

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  • Focus-dependent text change for TextBoxes in WPF

    - by Simon
    Hey there. I'm writing an application in WPF using the MVVM-pattern and will really often use TextBoxes. I don't want to use labels for the user to know user what the text box is for, i.e. I don't want something like this: <TextBlock> Name: </TextBlock> <TextBox /> Instead, I would like the TextBox to contain its own label. Statically, you would express it like this: <TextBox>Name</TextBox> If the cursor is displayed in the textbox, i.e. the TextBox gains focus, I want the description text to disappear. If the TextBox is left empty and it loses the focus, the description text should be shown again. It's similar to the search textbox of StackOverflow or the one of Firefox. (please tell me if your not sure what I mean). One TextBox's label may change at runtime, dependending on e.g. a ComboBox's selected element or a value in my ViewModel. (It's like in Firefox's search TextBox, if you select google from the search engins' menu, the TextBox's label changes to "Google", if you select "Yahoo" its set to "Yahoo"). Thus I want to be able to bind the label's content. Consider that I may already have a Binding on the Text-Property of the TextBox. How can implement such a behaviour and make it reusable for any of my TextBox's? Code is welcome but not needed; a description of what to do is enough. Thank you in advance.

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  • Grouping Categorized Data In WPF.

    - by VoidDweller
    Here is what I am trying to do. Dynamic Category: Columns can be 0 or more. Must contain 1 or more Type Columns. Will only be displayed if any row contains Type Column data associated with it. Data Rows: Will be added Asynchronously. Will be grouped by a Common Category column. Will add a Dynamic Category if it does not yet exist. Will add a Type Column if it does not yet exist within its appropriate Dynamic Category. Platform Info: WPF .Net 3.5 sp1 C# MVVM I have a few partially functional prototypes, but each has it's own major set of problems. Can any of you give me some guidance on this? Envision this nicely styled. :-) -------------------------------------------------------------------------- |[ Common Category ]|[ Dynamic Category 0 ]|[ Dynamic Category N ]| -------------------------------------------------------------------------- |[Header 1]|[Header 2]|[ Type 0 ]|[ Type N ]|[ Type 0 ]|[ Type N ]| -------------------------------------------------------------------------- |[Data 2 Group] | -------------------------------------------------------------------------- | Data A | Data 2 || Null | Data 1 || Data 0 | Data 1 || | Data B | Data 2 || Data 0 | Null || Data 0 | Data 1 || -------------------------------------------------------------------------- |[Data 1 Group] | -------------------------------------------------------------------------- | Data C | Data 1 || Null | Data 1 || Data 0 | Data 1 || | Data D | Data 1 || Null | Null || Data 0 | Null || -------------------------------------------------------------------------- Edit: Sorting and Paging is not necessary. I have looked at nested ListViews and DataGrids, dynamically building a Grid. Dynamically building a Grid and leveraging the SharedSizeGroup property seems the most promising strategy, but I am concerned about performance. Would a better approach be to consider this a dynamic report? If so, what should I be looking at? Thanks for your help.

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