feat(NavigationService): exception handling && decouple by using mvvm toolkit messenger

LaoSparrow · LaoSparrow · commit 26c7c4e11557 · 2025-06-24T00:28:32.000+08:00
diff --git a/PCL.Neo/Messages/NavigationMessage.cs b/PCL.Neo/Messages/NavigationMessage.cs
@@ -0,0 +1,27 @@
+using PCL.Neo.Services;
+using PCL.Neo.ViewModels;
+using System;
+
+namespace PCL.Neo.Messages;
+
+public class NavigationMessage(
+    ViewModelBase? oldMainViewModel,
+    ViewModelBase? newMainViewModel,
+    ViewModelBase? oldSubViewModel,
+    ViewModelBase? newSubViewModel,
+    NavigationType navigationType)
+{
+    public static class Channels
+    {
+        public static readonly Guid Navigating = Guid.NewGuid();
+        public static readonly Guid Navigated = Guid.NewGuid();
+    }
+
+    public bool           IsMainViewModelChanged => oldMainViewModel != newMainViewModel;
+    public ViewModelBase? OldMainViewModel       => oldMainViewModel;
+    public ViewModelBase? NewMainViewModel       => newMainViewModel;
+    public bool           IsSubViewModelChanged  => oldSubViewModel != newSubViewModel;
+    public ViewModelBase? OldSubViewModel        => oldSubViewModel;
+    public ViewModelBase? NewSubViewModel        => newSubViewModel;
+    public NavigationType NavigationType         => navigationType;
+}
diff --git a/PCL.Neo/Services/NavigationService.cs b/PCL.Neo/Services/NavigationService.cs
@@ -1,4 +1,6 @@
+using CommunityToolkit.Mvvm.Messaging;
 using Microsoft.Extensions.DependencyInjection;
+using PCL.Neo.Messages;
 using PCL.Neo.ViewModels;
 using System;
 using System.Collections.Generic;
@@ -9,8 +11,8 @@ namespace PCL.Neo.Services;
 
 public interface INavigationService
 {
-    public event Action<NavigationEventArgs>? Navigating;
-    public event Action<NavigationEventArgs>? Navigated;
+    // public event Action<NavigationMessage>? Navigating;
+    // public event Action<NavigationMessage>? Navigated;
 
     public ViewModelBase? CurrentMainViewModel { get; }
 
@@ -30,28 +32,12 @@ public enum NavigationType
     Backward
 }
 
-public class NavigationEventArgs(
-    ViewModelBase? oldMainViewModel,
-    ViewModelBase? newMainViewModel,
-    ViewModelBase? oldSubViewModel,
-    ViewModelBase? newSubViewModel,
-    NavigationType navigationType)
-{
-    public bool           IsMainViewModelChanged => oldMainViewModel != newMainViewModel;
-    public ViewModelBase? OldMainViewModel       => oldMainViewModel;
-    public ViewModelBase? NewMainViewModel       => newMainViewModel;
-    public bool           IsSubViewModelChanged  => oldSubViewModel != newSubViewModel;
-    public ViewModelBase? OldSubViewModel        => oldSubViewModel;
-    public ViewModelBase? NewSubViewModel        => newSubViewModel;
-    public NavigationType NavigationType         => navigationType;
-}
-
 public class NavigationService(IServiceProvider serviceProvider) : INavigationService
 {
     public IServiceProvider ServiceProvider { get; } = serviceProvider;
 
-    public event Action<NavigationEventArgs>? Navigating;
-    public event Action<NavigationEventArgs>? Navigated;
+    // public event Action<NavigationMessage>? Navigating;
+    // public event Action<NavigationMessage>? Navigated;
 
     // 导航历史记录
     private readonly LinkedList<(Type?, Type?)> _navigationHistory = [];
@@ -73,40 +59,50 @@ public class NavigationService(IServiceProvider serviceProvider) : INavigationSe
     /// <exception cref="InvalidOperationException"></exception>
     public async Task<(ViewModelBase? mainVm, ViewModelBase? subVm)> GoToAsync<T>() where T : ViewModelBase
     {
-        // T 可为 `MainViewModel` 或 `SubViewModel`
-        // 根据 T 上附加的 attribute 判断
-        var mainAttr = typeof(T).GetCustomAttribute<MainViewModelAttribute>();
-        var subAttr  = typeof(T).GetCustomAttribute<SubViewModelAttribute>();
-        if (mainAttr is null && subAttr is null)
-            throw new InvalidOperationException(
-                $"ViewModel {typeof(T).Name} does not have a {nameof(MainViewModelAttribute)} or a {nameof(SubViewModelAttribute)}");
-        if (mainAttr is not null && subAttr is not null)
-            throw new InvalidOperationException(
-                $"ViewModel {typeof(T).Name} has both {nameof(MainViewModelAttribute)} and {nameof(SubViewModelAttribute)}");
-
-        Type? mainVmType;
-        Type? subVmType;
-        if (mainAttr is not null)
+        try
         {
-            mainVmType = typeof(T);
-            subVmType  = mainAttr.DefaultSubViewModelType;
+            // T 可为 `MainViewModel` 或 `SubViewModel`
+            // 根据 T 上附加的 attribute 判断
+            var mainAttr = typeof(T).GetCustomAttribute<MainViewModelAttribute>();
+            var subAttr = typeof(T).GetCustomAttribute<SubViewModelAttribute>();
+            if (mainAttr is null && subAttr is null)
+                throw new InvalidOperationException(
+                    $"ViewModel {typeof(T).Name} does not have a {nameof(MainViewModelAttribute)} or a {nameof(SubViewModelAttribute)}");
+            if (mainAttr is not null && subAttr is not null)
+                throw new InvalidOperationException(
+                    $"ViewModel {typeof(T).Name} has both {nameof(MainViewModelAttribute)} and {nameof(SubViewModelAttribute)}");
+
+            Type? mainVmType;
+            Type? subVmType;
+            if (mainAttr is not null)
+            {
+                mainVmType = typeof(T);
+                subVmType = mainAttr.DefaultSubViewModelType;
+            }
+            else // if (subAttr is not null)
+            {
+                mainVmType = subAttr!.MainViewModelType;
+                subVmType = typeof(T);
+            }
+
+            var mainVm = CurrentMainViewModel?.GetType() == mainVmType
+                ? CurrentMainViewModel
+                : (ViewModelBase)ServiceProvider.GetRequiredService(mainVmType);
+            var subVm = CurrentSubViewModel?.GetType() == subVmType
+                ? CurrentSubViewModel
+                : (ViewModelBase)ServiceProvider.GetRequiredService(subVmType);
+
+            await NavigateToAsync(mainVm, subVm);
+
+            return (mainVm, subVm);
         }
-        else // if (subAttr is not null)
+        catch (Exception ex)
         {
-            mainVmType = subAttr!.MainViewModelType;
-            subVmType  = typeof(T);
+            // TODO: logger
+            Console.WriteLine($"[{nameof(NavigationService)}] navigation failed: {ex}");
         }
 
-        var mainVm = CurrentMainViewModel?.GetType() == mainVmType
-            ? CurrentMainViewModel
-            : (ViewModelBase)ServiceProvider.GetRequiredService(mainVmType);
-        var subVm = CurrentSubViewModel?.GetType() == subVmType
-            ? CurrentSubViewModel
-            : (ViewModelBase)ServiceProvider.GetRequiredService(subVmType);
-
-        await NavigateToAsync(mainVm, subVm);
-
-        return (mainVm, subVm);
+        return (null, null);
     }
 
     /// <summary>
@@ -117,16 +113,26 @@ public class NavigationService(IServiceProvider serviceProvider) : INavigationSe
     /// <returns>(MainViewModel, SubViewModel)</returns>
     public async Task<(TM?, TS?)> GoToAsync<TM, TS>() where TM : ViewModelBase where TS : ViewModelBase
     {
-        var mainVm = CurrentMainViewModel?.GetType() == typeof(TM)
-            ? CurrentMainViewModel as TM
-            : ServiceProvider.GetRequiredService<TM>();
-        var subVm = CurrentSubViewModel?.GetType() == typeof(TS)
-            ? CurrentSubViewModel as TS
-            : ServiceProvider.GetRequiredService<TS>();
+        try
+        {
+            var mainVm = CurrentMainViewModel?.GetType() == typeof(TM)
+                ? CurrentMainViewModel as TM
+                : ServiceProvider.GetRequiredService<TM>();
+            var subVm = CurrentSubViewModel?.GetType() == typeof(TS)
+                ? CurrentSubViewModel as TS
+                : ServiceProvider.GetRequiredService<TS>();
 
-        await NavigateToAsync(mainVm, subVm);
+            await NavigateToAsync(mainVm, subVm);
 
-        return (mainVm, subVm);
+            return (mainVm, subVm);
+        }
+        catch (Exception ex)
+        {
+            // TODO: logger
+            Console.WriteLine($"[{nameof(NavigationService)}] navigation failed: {ex}");
+        }
+
+        return (null, null);
     }
 
     /// <summary>
@@ -139,25 +145,33 @@ protected async Task NavigateToAsync(ViewModelBase? main, ViewModelBase? sub,
         NavigationType                             navigationType = NavigationType.Forward)
     {
         var oldMainVm = CurrentMainViewModel;
-        var oldSubVm  = CurrentSubViewModel;
+        var oldSubVm = CurrentSubViewModel;
 
-        Navigating?.Invoke(new NavigationEventArgs(
+        // Navigating?.Invoke(new NavigationMessage(
+        //     oldMainVm, main,
+        //     oldSubVm, sub,
+        //     navigationType));
+        WeakReferenceMessenger.Default.Send(new NavigationMessage(
             oldMainVm, main,
             oldSubVm, sub,
-            navigationType));
+            navigationType), NavigationMessage.Channels.Navigating);
 
         if (navigationType == NavigationType.Forward)
             PushHistory(
                 oldMainVm?.GetType() ?? null,
                 oldSubVm?.GetType() ?? null);
 
         CurrentMainViewModel = main;
-        CurrentSubViewModel  = sub;
+        CurrentSubViewModel = sub;
 
-        Navigated?.Invoke(new NavigationEventArgs(
+        // Navigated?.Invoke(new NavigationMessage(
+        //     oldMainVm, main,
+        //     oldSubVm, sub,
+        //     navigationType));
+        WeakReferenceMessenger.Default.Send(new NavigationMessage(
             oldMainVm, main,
             oldSubVm, sub,
-            navigationType));
+            navigationType), NavigationMessage.Channels.Navigated);
     }
 
     /// <summary>
@@ -167,11 +181,21 @@ protected async Task NavigateToAsync(ViewModelBase? main, ViewModelBase? sub,
     /// <returns>(MainViewModel, SubViewModel)</returns>
     public async Task<(ViewModelBase? mainVm, ViewModelBase? subVm)> GoBackAsync()
     {
-        if (!TryPopHistory(out var main, out var sub))
-            return (CurrentMainViewModel, CurrentSubViewModel);
+        try
+        {
+            if (!TryPopHistory(out var main, out var sub))
+                return (CurrentMainViewModel, CurrentSubViewModel);
+
+            await NavigateToAsync(main, sub, NavigationType.Backward);
+            return (main, sub);
+        }
+        catch (Exception ex)
+        {
+            // TODO: logger
+            Console.WriteLine($"[{nameof(NavigationService)}] navigation failed: {ex}");
+        }
 
-        await NavigateToAsync(main, sub, NavigationType.Backward);
-        return (main, sub);
+        return (null, null);
     }
 
     /// <summary>
diff --git a/PCL.Neo/ViewModels/Home/HomeSubViewModel.cs b/PCL.Neo/ViewModels/Home/HomeSubViewModel.cs
@@ -195,7 +195,9 @@ private void ManageVersions()
     private async Task OpenGameSettings()
     {
         // 导航到游戏设置视图
-        _navigationService.NavigateTo(Ioc.Default.GetRequiredService<HomeViewModelBackup>(), _gameSettingsViewModel);
+        // TODO: NavigationService 设计某个可以传特定实例的方法
+
+        // _navigationService.NavigateTo(Ioc.Default.GetRequiredService<HomeViewModelBackup>(), _gameSettingsViewModel);
 
         // 如果版本ID不为空，初始化为当前选中的版本
         if (SelectedGameVersion != null)
diff --git a/PCL.Neo/ViewModels/HomeViewModel.cs b/PCL.Neo/ViewModels/HomeViewModel.cs
@@ -7,6 +7,8 @@
 using System.Threading.Tasks;
 using Avalonia.Media.Imaging;
 using Avalonia.Platform;
+using CommunityToolkit.Mvvm.Messaging;
+using PCL.Neo.Messages;
 using SkiaSharp;
 using System.IO;
 
@@ -48,15 +50,30 @@ public HomeViewModel(INavigationService navigationService, UserService userServi
         // 订阅用户更改事件
         _userService.CurrentUserChanged += OnCurrentUserChanged;
 
-        // 订阅子视图模型变化
-        // FIXME: TODO: potential memory leak
-        _navigationService.Navigated += args => CurrentSubViewModel = args.NewSubViewModel;
-
         // 初始化当前用户信息
         if (_userService.CurrentUser != null)
         {
             UpdateCurrentUserInfo(_userService.CurrentUser);
         }
+
+        // 启用所有 Messenger 注册事件
+        IsActive = true;
+    }
+
+    protected override void OnActivated()
+    {
+        base.OnActivated();
+
+        Messenger.Register<HomeViewModel, NavigationMessage, Guid>(
+            this,
+            NavigationMessage.Channels.Navigated,
+            (_, m) => OnNavigated(m));
+    }
+
+    private void OnNavigated(NavigationMessage message)
+    {
+        // 订阅子视图模型变化
+        CurrentSubViewModel = message.NewSubViewModel;
     }
 
     private void OnCurrentUserChanged(UserInfo? user)
diff --git a/PCL.Neo/ViewModels/MainWindowViewModel.cs b/PCL.Neo/ViewModels/MainWindowViewModel.cs
@@ -1,9 +1,11 @@
 using Avalonia.Controls;
 using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
+using CommunityToolkit.Mvvm.Messaging;
 using PCL.Neo.Controls.MyMsg;
 using PCL.Neo.Services;
 using PCL.Neo.Helpers;
+using PCL.Neo.Messages;
 using System;
 using System.Threading.Tasks;
 
@@ -62,22 +64,38 @@ public MainWindowViewModel()
         public MainWindowViewModel(Window window)
         {
             this._window = window;
+
+            // 启用所有 Messenger 注册事件
+            IsActive = true;
         }
 
         public MainWindowViewModel(INavigationService navigationService)
         {
             NavigationService = navigationService;
-            NavigationService.Navigated += args =>
-            {
-                if (args.IsMainViewModelChanged)
-                    CurrentViewModel    = args.NewMainViewModel;
-                if (args.IsSubViewModelChanged)
-                    CurrentSubViewModel = args.NewSubViewModel;
-                // 更新返回按钮状态
-                CanGoBack = NavigationService.CanGoBack;
-                // 由外部的页面跳转反向触发设置按钮状态
-                UpdateNavBtnState();
-            };
+
+            // 启用所有 Messenger 注册事件
+            IsActive = true;
+        }
+
+        protected override void OnActivated()
+        {
+            base.OnActivated();
+
+            Messenger.Register<MainWindowViewModel, NavigationMessage, Guid>(
+                this, NavigationMessage.Channels.Navigated,
+                (_, m) => OnNavigated(m));
+        }
+
+        public void OnNavigated(NavigationMessage message)
+        {
+            if (message.IsMainViewModelChanged)
+                CurrentViewModel    = message.NewMainViewModel;
+            if (message.IsSubViewModelChanged)
+                CurrentSubViewModel = message.NewSubViewModel;
+            // 更新返回按钮状态
+            CanGoBack = NavigationService.CanGoBack;
+            // 由外部的页面跳转反向触发设置按钮状态
+            UpdateNavBtnState();
         }
 
         [RelayCommand]
diff --git a/PCL.Neo/ViewModels/ViewModelBase.cs b/PCL.Neo/ViewModels/ViewModelBase.cs
@@ -2,7 +2,7 @@
 
 namespace PCL.Neo.ViewModels;
 
-public partial class ViewModelBase : ObservableObject
+public partial class ViewModelBase : ObservableRecipient
 {
 
 }
diff --git a/PCL.Neo/Views/MainWindow.axaml.cs b/PCL.Neo/Views/MainWindow.axaml.cs

Original file line number	Diff line number	Diff line change
`@@ -2,7 +2,7 @@`
`2`	`2`
`3`	`3`	`namespace PCL.Neo.ViewModels;`
`4`	`4`
`5`		`-public partial class ViewModelBase : ObservableObject`
	`5`	`+public partial class ViewModelBase : ObservableRecipient`
`6`	`6`	`{`
`7`	`7`
`8`	`8`	`}`