增加ViewModelBase 生命周期控制View

Source/Store.Management.Framework/Controls/ConfirmDialog.cs

@@ -32,7 +32,7 @@ public static class IDialogServiceExtension
 /// <summary>
 /// 确定取消对话框 ViewModel
 /// </summary>
-public class ConfirmDialogViewModel : BindableBase, IDialogAware
+public class ConfirmDialogViewModel : ViewModelBase, IDialogAware
 {
 	public ConfirmDialogViewModel()
 	{
@@ -286,4 +286,4 @@ public abstract class ConfirmDialogViewModel<TParameter, TResult> : ConfirmDialo
 //public abstract class ConfirmDialogParameterViewModel : ConfirmDialogViewModel<ConfirmDialogParameterViewModel.Parameter>
 //{
 //	public abstract class Parameter;
-//}
+//}

Source/Store.Management.Framework/Controls/ViewLifecycle.cs

@@ -0,0 +1,85 @@
+using Prism.Services.Dialogs;
+using System.ComponentModel;
+using System.Windows;
+using System.Windows.Controls;
+
+namespace Store.Management.Framework.Controls;
+
+internal static class ViewLifecycle
+{
+    // 卸载时 DataContext 可能已改变，记录实际收到 OnLoaded 的实例。
+    private static readonly DependencyProperty LoadedViewModelProperty =
+        DependencyProperty.RegisterAttached("LoadedViewModel", typeof(ViewModelBase), typeof(ViewLifecycle));
+
+    internal static void Register()
+    {
+        foreach (Type type in new[] { typeof(UserControl), typeof(Window) })
+        {
+            FrameworkElement.DataContextProperty.OverrideMetadata(type,
+                new FrameworkPropertyMetadata(null, OnDataContextChanged));
+        }
+    }
+
+    private static void OnDataContextChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
+    {
+        if (sender is Window window)
+        {
+            if (e.OldValue is ViewModelBase)
+            {
+                window.Activated -= OnActivated;
+                window.Deactivated -= OnDeactivated;
+                window.Closing -= OnClosing;
+                window.Closed -= OnClosed;
+            }
+            if (e.NewValue is ViewModelBase)
+            {
+                window.Activated += OnActivated;
+                window.Deactivated += OnDeactivated;
+                window.Closing += OnClosing;
+                window.Closed += OnClosed;
+            }
+            if (window is IDialogWindow) return; // Prism 弹窗由内容页接收加载与卸载。
+        }
+        var view = (FrameworkElement)sender;
+        if (e.OldValue is ViewModelBase)
+        {
+            view.Loaded -= OnLoaded;
+            view.Unloaded -= OnUnloaded;
+        }
+        if (e.NewValue is ViewModelBase)
+        {
+            view.Loaded += OnLoaded;
+            view.Unloaded += OnUnloaded;
+        }
+        if (view.IsLoaded || view.GetValue(LoadedViewModelProperty) != null)
+            UpdateViewModel(view);
+    }
+
+    private static void OnLoaded(object sender, RoutedEventArgs e)
+        => UpdateViewModel((FrameworkElement)sender);
+
+    private static void OnActivated(object? sender, EventArgs e) => (((Window)sender!).DataContext as ViewModelBase)?.OnActivated();
+    private static void OnDeactivated(object? sender, EventArgs e) => (((Window)sender!).DataContext as ViewModelBase)?.OnDeactivated();
+    private static void OnClosing(object? sender, CancelEventArgs e) => (((Window)sender!).DataContext as ViewModelBase)?.OnClosing(e);
+    private static void OnClosed(object? sender, EventArgs e) => (((Window)sender!).DataContext as ViewModelBase)?.OnClosed();
+
+    private static void UpdateViewModel(FrameworkElement view)
+    {
+        // 共享父级 DataContext 的页眉、导航栏等子控件不拥有页面生命周期。
+        var source = DependencyPropertyHelper.GetValueSource(view, FrameworkElement.DataContextProperty);
+        var next = source.BaseValueSource == BaseValueSource.Inherited ? null : view.DataContext as ViewModelBase;
+        var previous = (ViewModelBase?)view.GetValue(LoadedViewModelProperty);
+        if (ReferenceEquals(previous, next)) return;
+        view.SetValue(LoadedViewModelProperty, next);
+        previous?.OnUnloaded();
+        next?.OnLoaded();
+    }
+
+    private static void OnUnloaded(object sender, RoutedEventArgs e)
+    {
+        var view = (FrameworkElement)sender;
+        var previous = (ViewModelBase?)view.GetValue(LoadedViewModelProperty);
+        view.ClearValue(LoadedViewModelProperty);
+        previous?.OnUnloaded();
+    }
+}

Source/Store.Management.Framework/Controls/ViewModelBase.cs

@@ -0,0 +1,14 @@
+using Prism.Mvvm;
+using System.ComponentModel;
+
+namespace Store.Management.Framework.Controls;
+
+public abstract class ViewModelBase : BindableBase
+{
+    protected internal virtual void OnLoaded() { }
+    protected internal virtual void OnUnloaded() { }
+    protected internal virtual void OnActivated() { }
+    protected internal virtual void OnDeactivated() { }
+    protected internal virtual void OnClosing(CancelEventArgs e) { }
+    protected internal virtual void OnClosed() { }
+}

Source/Store.Management.Framework/FrameworkApplication.cs

@@ -26,6 +26,8 @@ public abstract class FrameworkApplication : PrismApplication
 	private IStatusBarService StatusBarService;
 	private IMessageBoxService MessageBoxService;
 	private static bool FatalShutdown = false;
+	static FrameworkApplication() => Controls.ViewLifecycle.Register();
+
 	protected FrameworkApplication()
 	{
 		DispatcherUnhandledException += OnDispatcherUnhandledException;

Source/Store.Management/ViewModels/FrameworkTestPageViewModel.cs

@@ -2,12 +2,12 @@ using Prism.Commands;
 using MAX.Notification;
 using Store.Management.Notifications;
 using Prism.Ioc;
-using Prism.Mvvm;
+using Store.Management.Framework.Controls;
 using Prism.Services.Dialogs;
 using Store.Management.Services;
 using Store.Management.Views;
 namespace Store.Management.ViewModels;
-public sealed class FrameworkTestPageViewModel : BindableBase
+public sealed class FrameworkTestPageViewModel : ViewModelBase
 {
     private readonly IContainerProvider container;
     private readonly SingletonProbe singleton;

Source/Store.Management/ViewModels/MainViewModel.cs

@@ -1,5 +1,5 @@
 using Store.Management.Framework.Services;
-using Prism.Mvvm;
+using Store.Management.Framework.Controls;
 using Prism.Regions;
 using System;
 using System.Collections.Generic;
@@ -9,7 +9,7 @@ using System.Threading.Tasks;
 
 namespace Store.Management.ViewModels
 {
-	partial class MainViewModel : BindableBase
+	partial class MainViewModel : ViewModelBase
 	{
 		private readonly IRegionManager _regionManager;
 		public IStatusBarService StatusBar { get; }

Source/Store.Management/ViewModels/UserManagementPageViewModel.cs

@@ -12,7 +12,7 @@ using System.Windows.Controls.Primitives;
 
 namespace Store.Management.ViewModels;
 
-public sealed class UserManagementPageViewModel(IUserService userService, IDialogService dialogs, IStatusBarService statusBar) : BindableBase
+public sealed class UserManagementPageViewModel(IUserService userService, IDialogService dialogs, IStatusBarService statusBar) : ViewModelBase
 {
     public const int KeywordLimit = 100;
     private string appliedKeyword = "";
@@ -37,6 +37,10 @@ public sealed class UserManagementPageViewModel(IUserService userService, IDialo
 
     public AsyncDelegateCommand LoginCommand => field ??= new(LoginAsync);
 
+	protected override void OnLoaded()
+	{
+		base.OnLoaded();
+	}
     private async Task LoginAsync()
     {
         ButtonResult result = ButtonResult.None;

Tests/Store.Management.App.SmokeTests/Program.cs

@@ -58,8 +58,46 @@ class Program
             Console.WriteLine("PASS: LoginViewModel -> ILoginService -> AuthApi, retry, password contract and cancellation.");
             return 0;
         }
-        App app = args.Contains("--status-bar") ? new App() : new TestApp(client);
+        App app = args.Contains("--status-bar") || args.Contains("--view-lifecycle") ? new App() : new TestApp(client);
         app.InitializeComponent();
+        if (args.Contains("--view-lifecycle"))
+        {
+            app.ShutdownMode = ShutdownMode.OnExplicitShutdown;
+            var pageVm = new LifecycleProbe();
+            var windowVm = new LifecycleProbe();
+            var page = new UserControl { DataContext = pageVm, Content = new UserControl() };
+            var window = new Window { DataContext = windowVm, Content = page };
+            window.Show();
+            app.Dispatcher.Invoke(() => { }, DispatcherPriority.ApplicationIdle);
+            Check(pageVm.Loads == 1 && windowVm.Loads == 1, $"窗口和页面各加载一次：{windowVm.Loads}/{pageVm.Loads}");
+            window.Content = null;
+            app.Dispatcher.Invoke(() => { }, DispatcherPriority.ApplicationIdle);
+            Check(pageVm.Unloads == 1, "移出页面触发卸载");
+            window.Content = page;
+            app.Dispatcher.Invoke(() => { }, DispatcherPriority.ApplicationIdle);
+            Check(pageVm.Loads == 2, "重新加入页面再次加载");
+            var replacement = new LifecycleProbe();
+            page.DataContext = replacement;
+            Check(pageVm.Unloads == 2 && replacement.Loads == 1, "已加载的页面更换 ViewModel 后转移通知");
+            windowVm.CancelClose = true;
+            window.Close();
+            Check(window.IsVisible && windowVm.Closes == 0, "ViewModel 可以取消关闭");
+            windowVm.CancelClose = false;
+            window.Close();
+            Check(windowVm.Closes == 1, "窗口关闭后通知 ViewModel");
+            var dialogVm = new LifecycleProbe();
+            var dialog = new DialogWindow
+            {
+                DataContext = dialogVm,
+                Content = new UserControl { DataContext = dialogVm }
+            };
+            dialog.Show();
+            app.Dispatcher.Invoke(() => { }, DispatcherPriority.ApplicationIdle);
+            Check(dialogVm.Loads == 1, "Prism 弹窗宿主和内容共享 ViewModel 时只加载一次");
+            dialog.Close();
+            Console.WriteLine("PASS: view and window lifecycle.");
+            return 0;
+        }
         int exitCode = 0;
         app.Dispatcher.BeginInvoke(DispatcherPriority.ApplicationIdle, new Action(async () =>
         {
@@ -227,6 +265,18 @@ class Program
     static void Check(bool success, string message) { if (!success) throw new Exception(message); }
 }
 
+sealed class LifecycleProbe : ViewModelBase
+{
+    public int Loads { get; private set; }
+    public int Unloads { get; private set; }
+    public int Closes { get; private set; }
+    public bool CancelClose { get; set; }
+    protected override void OnLoaded() => Loads++;
+    protected override void OnUnloaded() => Unloads++;
+    protected override void OnClosing(System.ComponentModel.CancelEventArgs e) => e.Cancel = CancelClose;
+    protected override void OnClosed() => Closes++;
+}
+
 sealed class LoginHandler : HttpMessageHandler
 {
     public int RequestCount { get; private set; }