Merge pull request #11 from RolandKoenig/10-provide-viewmodel-propert…

…y-which-does-not-bubble-like-datacontext

10 Add ViewFor property on MvvmWindow and MvvmUserControl to handle bubbling of DataContext

README.md

@@ -116,7 +116,10 @@ when the ViewService can not be found.
 In order for that to work, you also have to use one of the base classes MvvmWindow or MvvmUserControl on the
 view side. They are responsible for attaching to the view model and detaching again, when
 the view is closed. Be sure that you also derive from the correct base class in
-the corresponding code behind.
+the corresponding code behind. Attention: You also have to set the 'ViewFor' property
+on MvvmWindow or MvvmUserControl. The reason behind this is that DataContext is also set
+on child elements automatically. If one of these would also derive from MvvmWindow oder
+MvvmUserControl, these one would attach to your ViewModel too.
 
 ```xml
 <ext:MvvmWindow xmlns="https://github.com/avaloniaui"
@@ -126,7 +129,8 @@ the corresponding code behind.
         xmlns:ext="https://github.com/RolandK.AvaloniaExtensions"
         xmlns:local="clr-namespace:RolandK.AvaloniaExtensions.TestApp"
         mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
-        x:Class="RolandK.AvaloniaExtensions.TestApp.MainWindow">
+        x:Class="RolandK.AvaloniaExtensions.TestApp.MainWindow"
+        ViewFor="{x:Type [YourViewModelTypeHere]}">
 </ext:MvvmWindow>
 ```
 

src/RolandK.AvaloniaExtensions.TestApp/MainWindow.axaml

@@ -8,6 +8,7 @@
         x:Class="RolandK.AvaloniaExtensions.TestApp.MainWindow"
         Title="{Binding Path=Title}"
         ExtendClientAreaToDecorationsHint="True"
+        ViewFor="{x:Type local:MainWindowViewModel}"
         DataContext="{ext:CreateUsingDependencyInjection {x:Type local:MainWindowViewModel}}"
         d:DataContext="{x:Static local:MainWindowViewModel.DesignViewModel}">
     <ext:MainWindowFrame>

src/RolandK.AvaloniaExtensions.TestApp/MainWindow.axaml.cs

@@ -1,4 +1,4 @@
-using RolandK.AvaloniaExtensions.Mvvm.Markup;
+using RolandK.AvaloniaExtensions.Mvvm.Controls;
 
 namespace RolandK.AvaloniaExtensions.TestApp;
 

src/RolandK.AvaloniaExtensions.Tests/Mvvm/MvvmUserControlTests.cs

@@ -1,9 +1,9 @@
 using Avalonia.Controls;
 using CommunityToolkit.Mvvm.ComponentModel;
 using RolandK.AvaloniaExtensions.Mvvm;
-using RolandK.AvaloniaExtensions.Mvvm.Markup;
+using RolandK.AvaloniaExtensions.Mvvm.Controls;
 using RolandK.AvaloniaExtensions.Tests.Util;
-using RolandK.AvaloniaExtensions.Views;
+using RolandK.AvaloniaExtensions.Controls;
 using RolandK.AvaloniaExtensions.ViewServices;
 using RolandK.AvaloniaExtensions.ViewServices.Base;
 
@@ -23,6 +23,7 @@ public Task Attach_MvvmUserControl_to_ViewModel()
 
             // Act
             testMvvmControl.DataContext = testViewModel;
+            testMvvmControl.ViewFor = typeof(TestViewModel);
             var testRoot = new TestRootWindow(testMvvmControl);
 
             // Assert
@@ -43,6 +44,7 @@ public Task Attach_MvvmUserControl_to_ViewModel_then_detach()
 
             // Act
             testMvvmControl.DataContext = testViewModel;
+            testMvvmControl.ViewFor = typeof(TestViewModel);
             var testRoot = new TestRootWindow(testMvvmControl);
 
             testRoot.Content = new Grid();
@@ -65,6 +67,7 @@ public Task Attach_MvvmUserControl_to_ViewModel_then_detach_with_Grid_in_control
 
             // Act
             testMvvmControl.DataContext = testViewModel;
+            testMvvmControl.ViewFor = typeof(TestViewModel);
 
             var mvvmControlContainer = new Grid();
             mvvmControlContainer.Children.Add(testMvvmControl);
@@ -95,6 +98,7 @@ public Task Attach_MvvmUserControl_to_ViewModel_then_close_parent_Window_using_V
 
             // Act
             testMvvmControl.DataContext = testViewModel;
+            testMvvmControl.ViewFor = typeof(TestViewModel);
             testViewModel.TriggerCloseWindowRequest();
 
             parentWindow.Content = null;
@@ -116,6 +120,7 @@ public Task Attach_MvvmUserControl_to_ViewModel_get_ViewService_MessageBox()
 
             // Act
             testMvvmControl.DataContext = testViewModel;
+            testMvvmControl.ViewFor = typeof(TestViewModel);
             var mainWindowFrame = new MainWindowFrame(testMvvmControl);
             var testRoot = new TestRootWindow(mainWindowFrame);
             var messageBoxService = testViewModel.TryGetViewService<IMessageBoxViewService>();

src/RolandK.AvaloniaExtensions.Tests/Mvvm/MvvmWindowTests.cs

@@ -1,9 +1,9 @@
 using Avalonia.Controls;
 using CommunityToolkit.Mvvm.ComponentModel;
 using RolandK.AvaloniaExtensions.Mvvm;
-using RolandK.AvaloniaExtensions.Mvvm.Markup;
+using RolandK.AvaloniaExtensions.Mvvm.Controls;
 using RolandK.AvaloniaExtensions.Tests.Util;
-using RolandK.AvaloniaExtensions.Views;
+using RolandK.AvaloniaExtensions.Controls;
 using RolandK.AvaloniaExtensions.ViewServices;
 using RolandK.AvaloniaExtensions.ViewServices.Base;
 
@@ -23,6 +23,7 @@ await UnitTestApplication.RunInApplicationContextAsync(() =>
 
             // Act
             mvvmWindow.DataContext = testViewModel;
+            mvvmWindow.ViewFor = typeof(TestViewModel);
             mvvmWindow.Show();
 
             // Assert
@@ -45,6 +46,7 @@ await UnitTestApplication.RunInApplicationContextAsync(() =>
 
             // Act
             mvvmWindow.DataContext = testViewModel;
+            mvvmWindow.ViewFor = typeof(TestViewModel);
             mvvmWindow.Show();
 
             testViewModel.TriggerCloseWindowRequest();
@@ -71,6 +73,7 @@ await UnitTestApplication.RunInApplicationContextAsync(async Task () =>
 
             // Act
             mvvmWindow.DataContext = testViewModel;
+            mvvmWindow.ViewFor = typeof(TestViewModel);
             var showDialogTask = mvvmWindow.ShowDialog<object>(topLevelWindow);
 
             var dialogResult = new object();
@@ -100,6 +103,7 @@ await UnitTestApplication.RunInApplicationContextAsync(() =>
 
             // Act
             mvvmWindow.DataContext = testViewModel;
+            mvvmWindow.ViewFor = typeof(TestViewModel);
             mvvmWindow.Show();
 
             var messageBoxService = testViewModel.TryGetViewService<IOpenFileViewService>();
@@ -124,6 +128,7 @@ await UnitTestApplication.RunInApplicationContextAsync(() =>
 
             // Act
             mvvmWindow.DataContext = testViewModel;
+            mvvmWindow.ViewFor = typeof(TestViewModel);
             mvvmWindow.Show();
 
             var messageBoxService = testViewModel.TryGetViewService<ISaveFileViewService>();
@@ -151,6 +156,7 @@ await UnitTestApplication.RunInApplicationContextAsync(() =>
 
             // Act
             mvvmWindow.DataContext = testViewModel;
+            mvvmWindow.ViewFor = typeof(TestViewModel);
             mvvmWindow.Show();
 
             var messageBoxService = testViewModel.TryGetViewService<IMessageBoxViewService>();
@@ -178,6 +184,7 @@ await UnitTestApplication.RunInApplicationContextAsync(() =>
 
             // Act
             mvvmWindow.DataContext = testViewModel;
+            mvvmWindow.ViewFor = typeof(TestViewModel);
             mvvmWindow.Show();
 
             var messageBoxService = testViewModel.TryGetViewService<IMessageBoxViewService>();

src/RolandK.AvaloniaExtensions.Tests/ViewServices/DefaultViewServicesTests.cs

@@ -1,7 +1,7 @@
 using Avalonia.Controls;
-using RolandK.AvaloniaExtensions.Mvvm.Markup;
+using RolandK.AvaloniaExtensions.Mvvm.Controls;
 using RolandK.AvaloniaExtensions.Tests.Util;
-using RolandK.AvaloniaExtensions.Views;
+using RolandK.AvaloniaExtensions.Controls;
 using RolandK.AvaloniaExtensions.ViewServices;
 
 namespace RolandK.AvaloniaExtensions.Tests.ViewServices;

src/RolandK.AvaloniaExtensions.Tests/ViewServices/ViewServiceHostUserControlTests.cs

@@ -1,4 +1,4 @@
-using RolandK.AvaloniaExtensions.Mvvm.Markup;
+using RolandK.AvaloniaExtensions.Mvvm.Controls;
 using RolandK.AvaloniaExtensions.Tests.Util;
 using RolandK.AvaloniaExtensions.ViewServices;
 using RolandK.AvaloniaExtensions.ViewServices.Base;

src/RolandK.AvaloniaExtensions.Tests/Views/DialogBoxControlTests.cs

@@ -1,7 +1,7 @@
 using Avalonia.Controls;
 using Avalonia.LogicalTree;
 using RolandK.AvaloniaExtensions.Tests.Util;
-using RolandK.AvaloniaExtensions.Views;
+using RolandK.AvaloniaExtensions.Controls;
 
 namespace RolandK.AvaloniaExtensions.Tests.Views;
 

src/RolandK.AvaloniaExtensions.Tests/Views/DialogHostControlTests.cs

@@ -1,7 +1,7 @@
 using Avalonia.Controls;
 using Avalonia.LogicalTree;
 using RolandK.AvaloniaExtensions.Tests.Util;
-using RolandK.AvaloniaExtensions.Views;
+using RolandK.AvaloniaExtensions.Controls;
 
 namespace RolandK.AvaloniaExtensions.Tests.Views;
 

src/RolandK.AvaloniaExtensions.Tests/Views/MainWindowFrameTests.cs

@@ -1,7 +1,7 @@
 using Avalonia.Controls;
 using Avalonia.LogicalTree;
 using RolandK.AvaloniaExtensions.Tests.Util;
-using RolandK.AvaloniaExtensions.Views;
+using RolandK.AvaloniaExtensions.Controls;
 
 namespace RolandK.AvaloniaExtensions.Tests.Views;
 

src/RolandK.AvaloniaExtensions/Attributes.cs

@@ -3,9 +3,9 @@
 
 [assembly: XmlnsDefinition(
     "https://github.com/RolandK.AvaloniaExtensions", 
-    "RolandK.AvaloniaExtensions.Views")]
+    "RolandK.AvaloniaExtensions.Controls")]
 [assembly: XmlnsDefinition(
     "https://github.com/RolandK.AvaloniaExtensions", 
-    "RolandK.AvaloniaExtensions.Mvvm.Markup")]
+    "RolandK.AvaloniaExtensions.Mvvm.Controls")]
 
 [assembly: InternalsVisibleTo("RolandK.AvaloniaExtensions.Tests")]    

src/RolandK.AvaloniaExtensions/Views/DialogBoxControl.axaml → src/RolandK.AvaloniaExtensions/Controls/DialogBoxControl.axaml

@@ -3,7 +3,7 @@
              xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
              mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
-             x:Class="RolandK.AvaloniaExtensions.Views.DialogBoxControl">
+             x:Class="RolandK.AvaloniaExtensions.Controls.DialogBoxControl">
     <Border BorderThickness="1"
             BorderBrush="{DynamicResource DialogBoxControlBorderBrush}">
         <DockPanel LastChildFill="True">

src/RolandK.AvaloniaExtensions/Views/DialogBoxControl.axaml.cs → src/RolandK.AvaloniaExtensions/Controls/DialogBoxControl.axaml.cs

@@ -1,7 +1,7 @@
 using Avalonia.Controls;
 using Avalonia.Markup.Xaml;
 
-namespace RolandK.AvaloniaExtensions.Views;
+namespace RolandK.AvaloniaExtensions.Controls;
 
 public partial class DialogBoxControl : UserControl
 {
@@ -14,7 +14,7 @@ public string Header
         set => _txtHeader.Text = value;
     }
 
-    public Controls ContentArea
+    public Avalonia.Controls.Controls ContentArea
     {
         get => _gridContent.Children;
     }

src/RolandK.AvaloniaExtensions/Views/DialogHostControl.cs → src/RolandK.AvaloniaExtensions/Controls/DialogHostControl.cs

@@ -4,7 +4,7 @@
 using Avalonia.Layout;
 using Avalonia.Media;
 
-namespace RolandK.AvaloniaExtensions.Views;
+namespace RolandK.AvaloniaExtensions.Controls;
 
 public class DialogHostControl : Grid
 {

src/RolandK.AvaloniaExtensions/Views/MainWindowFrame.axaml → src/RolandK.AvaloniaExtensions/Controls/MainWindowFrame.axaml

@@ -2,9 +2,9 @@
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
-             xmlns:local="clr-namespace:RolandK.AvaloniaExtensions.Views"
+             xmlns:local="clr-namespace:RolandK.AvaloniaExtensions.Controls"
              mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
-             x:Class="RolandK.AvaloniaExtensions.Views.MainWindowFrame">
+             x:Class="RolandK.AvaloniaExtensions.Controls.MainWindowFrame">
     <Grid x:Name="CtrlFullWindowGrid">
         <Grid.RowDefinitions>
             <RowDefinition Height="30" />

src/RolandK.AvaloniaExtensions/Views/MainWindowFrame.axaml.cs → src/RolandK.AvaloniaExtensions/Controls/MainWindowFrame.axaml.cs

@@ -6,11 +6,10 @@
 using Avalonia.Markup.Xaml;
 using Avalonia.Media;
 using Avalonia.Threading;
-using RolandK.AvaloniaExtensions.Mvvm.Markup;
 
-namespace RolandK.AvaloniaExtensions.Views;
+namespace RolandK.AvaloniaExtensions.Controls;
 
-public partial class MainWindowFrame : MvvmUserControl
+public partial class MainWindowFrame : UserControl
 {
     public static readonly StyledProperty<MainWindowFrameStatus> StatusProperty =
         AvaloniaProperty.Register<MainWindowFrame, MainWindowFrameStatus>(
@@ -26,15 +25,15 @@ public partial class MainWindowFrame : MvvmUserControl
     private Panel _ctrlFooterArea;
     private Panel _ctrlStatusBar;
 
-    public Controls FullBackgroundArea => _ctrlFullBackgroundPanel.Children;
+    public Avalonia.Controls.Controls FullBackgroundArea => _ctrlFullBackgroundPanel.Children;
 
-    public Controls CustomTitleArea => _ctrlCustomTitleArea.Children;
+    public Avalonia.Controls.Controls CustomTitleArea => _ctrlCustomTitleArea.Children;
 
-    public Controls HeaderMenuArea => _ctrlHeaderMenuArea.Children;
+    public Avalonia.Controls.Controls HeaderMenuArea => _ctrlHeaderMenuArea.Children;
 
-    public Controls MainContentArea => _ctrlMainContentArea.Children;
+    public Avalonia.Controls.Controls MainContentArea => _ctrlMainContentArea.Children;
 
-    public Controls FooterArea => _ctrlFooterArea.Children;
+    public Avalonia.Controls.Controls FooterArea => _ctrlFooterArea.Children;
 
     public DialogHostControl Overlay { get; }
 

src/RolandK.AvaloniaExtensions/Views/MainWindowFrameStatus.cs → src/RolandK.AvaloniaExtensions/Controls/MainWindowFrameStatus.cs

@@ -1,4 +1,4 @@
-namespace RolandK.AvaloniaExtensions.Views;
+namespace RolandK.AvaloniaExtensions.Controls;
 
 public enum MainWindowFrameStatus
 {

src/RolandK.AvaloniaExtensions/Mvvm/Markup/MvvmUserControl.cs → src/RolandK.AvaloniaExtensions/Mvvm/Controls/MvvmUserControl.cs

@@ -5,13 +5,26 @@
 using RolandK.AvaloniaExtensions.ViewServices;
 using RolandK.AvaloniaExtensions.ViewServices.Base;
 
-namespace RolandK.AvaloniaExtensions.Mvvm.Markup;
+namespace RolandK.AvaloniaExtensions.Mvvm.Controls;
 
 public class MvvmUserControl : UserControl, IViewServiceHost
 {
     private IAttachableViewModel? _currentlyAttachedViewModel;
     private bool _isAttachedToLogicalTree;
     private ViewServiceContainer _viewServiceContainer;
+    private Type? _viewFor;
+
+    public Type? ViewFor
+    {
+        get => _viewFor;
+        set
+        {
+            if (_viewFor == value) { return; }
+
+            _viewFor = value;
+            this.OnViewForChanged();
+        }
+    }
 
     /// <inheritdoc />
     public ICollection<IViewService> ViewServices => _viewServiceContainer.ViewServices;
@@ -34,7 +47,7 @@ public MvvmUserControl(Control initialChild)
     protected override void OnAttachedToLogicalTree(LogicalTreeAttachmentEventArgs e)
     {
         _isAttachedToLogicalTree = true;
-        this.AttachToDataContext();
+        this.TryAttachToDataContext();
 
         base.OnAttachedToLogicalTree(e);
     }
@@ -54,23 +67,31 @@ protected override void OnDataContextChanged(EventArgs e)
         if (!_isAttachedToLogicalTree)
         {
             base.OnDataContextChanged(e);
+            return;
         }
-        else
-        {
-            this.DetachFromDataContext();
+
+        this.DetachFromDataContext();
 
-            base.OnDataContextChanged(e);
+        base.OnDataContextChanged(e);
 
-            this.AttachToDataContext();
-        }
+        this.TryAttachToDataContext();
+    }
+
+    private void OnViewForChanged()
+    {
+        if (!_isAttachedToLogicalTree) { return; }
+
+        this.DetachFromDataContext();
+        this.TryAttachToDataContext();
     }
 
-    private void AttachToDataContext()
+    private void TryAttachToDataContext()
     {
         if (_currentlyAttachedViewModel == this.DataContext) { return; }
 
         this.DetachFromDataContext();
-        if (this.DataContext is IAttachableViewModel dataContextAttachable)
+        if ((this.DataContext is IAttachableViewModel dataContextAttachable) &&
+            (this.DataContext.GetType() == this.ViewFor))
         {
             dataContextAttachable.ViewServiceRequest += this.OnDataContextAttachable_ViewServiceRequest;
             dataContextAttachable.CloseWindowRequest += this.OnDataContextAttachable_CloseWindowRequest;