From 056d22c87e74054f7fb3266dccbd2df866588526 Mon Sep 17 00:00:00 2001
From: Yuriy Durov <u.a.durov@gmail.com>
Date: Fri, 10 May 2024 18:22:22 +0400
Subject: [PATCH] Changes to stateful ViewModel lifecycle

---
 .../Interfaces/IStatefulViewModel.cs           |  5 +++++
 src/BitzArt.Blazor.MVVM/Models/PageBase.cs     |  4 ++++
 src/BitzArt.Blazor.MVVM/Models/ViewModel.cs    | 18 ++++++++++++------
 3 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/src/BitzArt.Blazor.MVVM/Interfaces/IStatefulViewModel.cs b/src/BitzArt.Blazor.MVVM/Interfaces/IStatefulViewModel.cs
index 3e88574..f53179e 100644
--- a/src/BitzArt.Blazor.MVVM/Interfaces/IStatefulViewModel.cs
+++ b/src/BitzArt.Blazor.MVVM/Interfaces/IStatefulViewModel.cs
@@ -7,5 +7,10 @@ internal interface IStatefulViewModel
 
     public void InitializeState();
     public Task InitializeStateAsync();
+
     public void OnStateRestored();
+    public Task OnStateRestoredAsync();
+
+    public void OnStateChanged();
+    public Task OnStateChangedAsync();
 }
diff --git a/src/BitzArt.Blazor.MVVM/Models/PageBase.cs b/src/BitzArt.Blazor.MVVM/Models/PageBase.cs
index 33c6c86..859070b 100644
--- a/src/BitzArt.Blazor.MVVM/Models/PageBase.cs
+++ b/src/BitzArt.Blazor.MVVM/Models/PageBase.cs
@@ -39,6 +39,7 @@ private static async Task RestoreComponentStateAsync(ViewModel viewModel, string
             var buffer = Convert.FromBase64String(state);
             var json = Encoding.UTF8.GetString(buffer);
             statefulViewModel.State = JsonSerializer.Deserialize(json, statefulViewModel.StateType, StateJsonOptionsProvider.Options)!;
+            await statefulViewModel.OnStateRestoredAsync();
             statefulViewModel.OnStateRestored();
         }
         else
@@ -48,6 +49,9 @@ private static async Task RestoreComponentStateAsync(ViewModel viewModel, string
             statefulViewModel.InitializeState();
             await statefulViewModel.InitializeStateAsync();
         }
+
+        statefulViewModel.OnStateChanged();
+        await statefulViewModel.OnStateChangedAsync();
     }
 
     /// <summary>
diff --git a/src/BitzArt.Blazor.MVVM/Models/ViewModel.cs b/src/BitzArt.Blazor.MVVM/Models/ViewModel.cs
index b785329..2c2702c 100644
--- a/src/BitzArt.Blazor.MVVM/Models/ViewModel.cs
+++ b/src/BitzArt.Blazor.MVVM/Models/ViewModel.cs
@@ -33,11 +33,7 @@ public abstract class ViewModel<TState> : ViewModel, IStatefulViewModel
     public TState State
     {
         get => _state;
-        set
-        {
-            _state = value;
-            OnStateChanged(State);
-        }
+        set => _state = value;
     }
 
     object IStatefulViewModel.State
@@ -69,8 +65,18 @@ public virtual Task InitializeStateAsync()
     /// </summary>
     public virtual void OnStateRestored() { }
 
+    public virtual Task OnStateRestoredAsync()
+    {
+        return Task.CompletedTask;
+    }
+
     /// <summary>
     /// Called when the state has changed.
     /// </summary>
-    public virtual void OnStateChanged(TState state) { }
+    public virtual void OnStateChanged() { }
+
+    public virtual Task OnStateChangedAsync()
+    {
+        return Task.CompletedTask;
+    }
 }