Merge pull request PrismLibrary#2171 from PrismLibrary/vml-opt-out

Make ViewModelLocator Opt-Out

src/Uno/Prism.Uno/PrismApplicationBase.cs

@@ -1,4 +1,5 @@
-using Prism.Events;
+using Prism.Common;
+using Prism.Events;
 using Prism.Ioc;
 using Prism.Logging;
 using Prism.Modularity;
@@ -88,7 +89,7 @@ public virtual void Initialize()
             var shell = CreateShell();
             if (shell != null)
             {
-                _containerExtension.Resolve<IRegionNavigationService>().NavigationFailed += (s, e) => Console.WriteLine($"Region navigation failed {e.Error}");
+                MvvmHelpers.AutowireViewModel(shell);
                 InitializeShell(shell);
 
                 void FinalizeInitialization()

src/Uno/Prism.Uno/Services/Dialogs/DialogService.cs

@@ -49,14 +49,14 @@ IDialogWindow CreateDialogWindow(string name)
         void ConfigureDialogWindowContent(string dialogName, IDialogWindow window, IDialogParameters parameters)
         {
             var content = _containerProvider.Resolve<object>(dialogName);
-            var dialogContent = content as FrameworkElement;
-            if (dialogContent == null)
+            if (!(content is FrameworkElement dialogContent))
             {
                 throw new NullReferenceException("A dialog's content must be a FrameworkElement");
             }
 
-            var viewModel = dialogContent.DataContext as IDialogAware;
-            if (viewModel == null)
+            MvvmHelpers.AutowireViewModel(content);
+
+            if (!(dialogContent.DataContext is IDialogAware viewModel))
             {
                 throw new NullReferenceException($"A dialog's ViewModel must implement the IDialogAware interface ({dialogContent.DataContext})");
             }

src/Wpf/Prism.Wpf/Common/MvvmHelpers.cs

@@ -1,7 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
-
+using Prism.Mvvm;
 #if HAS_WINUI
 using Windows.UI.Xaml;
 #else
@@ -15,6 +15,14 @@ namespace Prism.Common
     /// </summary>
     public static class MvvmHelpers
     {
+        internal static void AutowireViewModel(object viewOrViewModel)
+        {
+            if(viewOrViewModel is FrameworkElement view && ViewModelLocator.GetAutoWireViewModel(view) is null)
+            {
+                ViewModelLocator.SetAutoWireViewModel(view, true);
+            }
+        }
+
         /// <summary>
         /// Perform an <see cref="Action{T}"/> on a view and viewmodel.
         /// </summary>

src/Wpf/Prism.Wpf/Mvvm/ViewModelLocator.cs

@@ -16,24 +16,24 @@ public static class ViewModelLocator
         /// <summary>
         /// The AutoWireViewModel attached property.
         /// </summary>
-        public static DependencyProperty AutoWireViewModelProperty = DependencyProperty.RegisterAttached("AutoWireViewModel", typeof(bool), typeof(ViewModelLocator), new PropertyMetadata(defaultValue: false, propertyChangedCallback: AutoWireViewModelChanged));
+        public static DependencyProperty AutoWireViewModelProperty = DependencyProperty.RegisterAttached("AutoWireViewModel", typeof(bool?), typeof(ViewModelLocator), new PropertyMetadata(defaultValue: null, propertyChangedCallback: AutoWireViewModelChanged));
 
         /// <summary>
         /// Gets the value for the <see cref="AutoWireViewModelProperty"/> attached property.
         /// </summary>
         /// <param name="obj">The target element.</param>
         /// <returns>The <see cref="AutoWireViewModelProperty"/> attached to the <paramref name="obj"/> element.</returns>
-        public static bool GetAutoWireViewModel(DependencyObject obj)
+        public static bool? GetAutoWireViewModel(DependencyObject obj)
         {
-            return (bool)obj.GetValue(AutoWireViewModelProperty);
+            return (bool?)obj.GetValue(AutoWireViewModelProperty);
         }
 
         /// <summary>
         /// Sets the <see cref="AutoWireViewModelProperty"/> attached property.
         /// </summary>
         /// <param name="obj">The target element.</param>
         /// <param name="value">The value to attach.</param>
-        public static void SetAutoWireViewModel(DependencyObject obj, bool value)
+        public static void SetAutoWireViewModel(DependencyObject obj, bool? value)
         {
             obj.SetValue(AutoWireViewModelProperty, value);
         }
@@ -44,7 +44,8 @@ private static void AutoWireViewModelChanged(DependencyObject d, DependencyPrope
             if (!DesignerProperties.GetIsInDesignMode(d))
 #endif
             {
-                if ((bool)e.NewValue)
+                var value = (bool?)e.NewValue;
+                if (value.HasValue && value.Value)
                 {
                     ViewModelLocationProvider.AutoWireViewModelChanged(d, Bind);
                 }

src/Wpf/Prism.Wpf/PrismApplicationBase.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Windows;
+using Prism.Common;
 using Prism.Ioc;
 using Prism.Modularity;
 using Prism.Regions;
@@ -75,6 +76,7 @@ protected virtual void Initialize()
             var shell = CreateShell();
             if (shell != null)
             {
+                MvvmHelpers.AutowireViewModel(shell);
                 RegionManager.SetRegionManager(shell, _containerExtension.Resolve<IRegionManager>());
                 RegionManager.UpdateRegions();
                 InitializeShell(shell);

src/Wpf/Prism.Wpf/PrismBootstrapperBase.cs

@@ -1,4 +1,5 @@
-using Prism.Ioc;
+using Prism.Common;
+using Prism.Ioc;
 using Prism.Modularity;
 using Prism.Regions;
 using System;
@@ -72,6 +73,7 @@ protected virtual void Initialize()
             var shell = CreateShell();
             if (shell != null)
             {
+                MvvmHelpers.AutowireViewModel(shell);
                 RegionManager.SetRegionManager(shell, _containerExtension.Resolve<IRegionManager>());
                 RegionManager.UpdateRegions();
                 InitializeShell(shell);

src/Wpf/Prism.Wpf/Regions/RegionNavigationContentLoader.cs

@@ -102,6 +102,7 @@ protected virtual object CreateNewRegionItem(string candidateTargetContract)
             try
             {
                 newRegionItem = _container.Resolve<object>(candidateTargetContract);
+                MvvmHelpers.AutowireViewModel(newRegionItem);
             }
             catch (Exception e)
             {

src/Wpf/Prism.Wpf/Services/Dialogs/DialogService.cs

@@ -106,12 +106,12 @@ protected virtual IDialogWindow CreateDialogWindow(string name)
         protected virtual void ConfigureDialogWindowContent(string dialogName, IDialogWindow window, IDialogParameters parameters)
         {
             var content = _containerExtension.Resolve<object>(dialogName);
-            var dialogContent = content as FrameworkElement;
-            if (dialogContent == null)
+            if (!(content is FrameworkElement dialogContent))
                 throw new NullReferenceException("A dialog's content must be a FrameworkElement");
 
-            var viewModel = dialogContent.DataContext as IDialogAware;
-            if (viewModel == null)
+            MvvmHelpers.AutowireViewModel(dialogContent);
+
+            if (!(dialogContent.DataContext is IDialogAware viewModel))
                 throw new NullReferenceException("A dialog's ViewModel must implement the IDialogAware interface");
 
             ConfigureDialogWindowProperties(window, dialogContent, viewModel);