Adjust DetectChanges events so they can be used to get a notification…

… when all changes for an entity have been detected (#28356)

src/EFCore/ChangeTracking/ChangeTracker.cs

@@ -381,25 +381,63 @@ public event EventHandler<EntityStateChangedEventArgs> StateChanged
     }
 
     /// <summary>
-    ///     An event fired when detecting changes to the entity graph or a single entity is about to happen, either through an
+    ///     An event fired when detecting changes to a single entity is about to happen, either through an
     ///     explicit call to <see cref="DetectChanges" /> or <see cref="EntityEntry.DetectChanges" />, or automatically, such as part of
     ///     executing <see cref="DbContext.SaveChanges()" /> or <see cref="DbContext.SaveChangesAsync(System.Threading.CancellationToken)" />.
     /// </summary>
-    public event EventHandler<DetectChangesEventArgs> DetectingChanges
+    /// <remarks>
+    ///     <see cref="AutoDetectChangesEnabled" /> is set to <see langword="false" /> for the duration of the event to prevent an infinite
+    ///     loop of recursive automatic calls.
+    /// </remarks>
+    public event EventHandler<DetectEntityChangesEventArgs> DetectingEntityChanges
     {
-        add => ChangeDetector.DetectingChanges += value;
-        remove => ChangeDetector.DetectingChanges -= value;
+        add => ChangeDetector.DetectingEntityChanges += value;
+        remove => ChangeDetector.DetectingEntityChanges -= value;
     }
 
     /// <summary>
-    ///     An event fired when any changes have been detected to the entity graph or a single entity, either through an
+    ///     An event fired when any changes have been detected to a single entity, either through an
     ///     explicit call to <see cref="DetectChanges" /> or <see cref="EntityEntry.DetectChanges" />, or automatically, such as part of
     ///     executing <see cref="DbContext.SaveChanges()" /> or <see cref="DbContext.SaveChangesAsync(System.Threading.CancellationToken)" />.
     /// </summary>
-    public event EventHandler<DetectedChangesEventArgs> DetectedChanges
+    /// <remarks>
+    ///     <see cref="AutoDetectChangesEnabled" /> is set to <see langword="false" /> for the duration of the event to prevent an infinite
+    ///     loop of recursive automatic calls.
+    /// </remarks>
+    public event EventHandler<DetectedEntityChangesEventArgs> DetectedEntityChanges
+    {
+        add => ChangeDetector.DetectedEntityChanges += value;
+        remove => ChangeDetector.DetectedEntityChanges -= value;
+    }
+
+    /// <summary>
+    ///     An event fired when detecting changes to the entity graph about to happen, either through an
+    ///     explicit call to <see cref="DetectChanges" />, or automatically, such as part of
+    ///     executing <see cref="DbContext.SaveChanges()" /> or <see cref="DbContext.SaveChangesAsync(System.Threading.CancellationToken)" />.
+    /// </summary>
+    /// <remarks>
+    ///     <see cref="AutoDetectChangesEnabled" /> is set to <see langword="false" /> for the duration of the event to prevent an infinite
+    ///     loop of recursive automatic calls.
+    /// </remarks>
+    public event EventHandler<DetectChangesEventArgs> DetectingAllChanges
+    {
+        add => ChangeDetector.DetectingAllChanges += value;
+        remove => ChangeDetector.DetectingAllChanges -= value;
+    }
+
+    /// <summary>
+    ///     An event fired when any changes have been detected to the entity graph, either through an
+    ///     explicit call to <see cref="DetectChanges" />, or automatically, such as part of
+    ///     executing <see cref="DbContext.SaveChanges()" /> or <see cref="DbContext.SaveChangesAsync(System.Threading.CancellationToken)" />.
+    /// </summary>
+    /// <remarks>
+    ///     <see cref="AutoDetectChangesEnabled" /> is set to <see langword="false" /> for the duration of the event to prevent an infinite
+    ///     loop of recursive automatic calls.
+    /// </remarks>
+    public event EventHandler<DetectedChangesEventArgs> DetectedAllChanges
     {
-        add => ChangeDetector.DetectedChanges += value;
-        remove => ChangeDetector.DetectedChanges -= value;
+        add => ChangeDetector.DetectedAllChanges += value;
+        remove => ChangeDetector.DetectedAllChanges -= value;
     }
 
     /// <summary>

src/EFCore/ChangeTracking/DetectChangesEventArgs.cs

@@ -1,39 +1,14 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-using Microsoft.EntityFrameworkCore.ChangeTracking.Internal;
-
 namespace Microsoft.EntityFrameworkCore.ChangeTracking;
 
 /// <summary>
-///     Event arguments for the <see cref="ChangeTracker.DetectingChanges" /> event.
+///     Event arguments for the <see cref="ChangeTracker.DetectingAllChanges" /> event.
 /// </summary>
 /// <remarks>
 ///     See <see href="https://aka.ms/efcore-docs-state-changes">State changes of entities in EF Core</see> for more information and examples.
 /// </remarks>
 public class DetectChangesEventArgs : EventArgs
 {
-    private readonly InternalEntityEntry? _internalEntityEntry;
-    private EntityEntry? _entry;
-
-    /// <summary>
-    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
-    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
-    ///     any release. You should only use it directly in your code with extreme caution and knowing that
-    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
-    /// </summary>
-    [EntityFrameworkInternal]
-    public DetectChangesEventArgs(InternalEntityEntry? internalEntityEntry)
-    {
-        _internalEntityEntry = internalEntityEntry;
-    }
-
-    /// <summary>
-    ///     If detecting changes for a single entity, then this is the <see cref="EntityEntry" /> for that entity.
-    ///     If detecting changes for an entire graph, then <see langword="null" />.
-    /// </summary>
-    public virtual EntityEntry? Entry
-        => _internalEntityEntry == null
-            ? null
-            : (_entry ??= new EntityEntry(_internalEntityEntry));
 }

src/EFCore/ChangeTracking/DetectEntityChangesEventArgs.cs

@@ -0,0 +1,36 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Microsoft.EntityFrameworkCore.ChangeTracking.Internal;
+
+namespace Microsoft.EntityFrameworkCore.ChangeTracking;
+
+/// <summary>
+///     Event arguments for the <see cref="ChangeTracker.DetectingEntityChanges" /> event.
+/// </summary>
+/// <remarks>
+///     See <see href="https://aka.ms/efcore-docs-state-changes">State changes of entities in EF Core</see> for more information and examples.
+/// </remarks>
+public class DetectEntityChangesEventArgs : DetectChangesEventArgs
+{
+    private readonly InternalEntityEntry _internalEntityEntry;
+    private EntityEntry? _entry;
+
+    /// <summary>
+    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+    ///     any release. You should only use it directly in your code with extreme caution and knowing that
+    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+    /// </summary>
+    [EntityFrameworkInternal]
+    public DetectEntityChangesEventArgs(InternalEntityEntry internalEntityEntry)
+    {
+        _internalEntityEntry = internalEntityEntry;
+    }
+
+    /// <summary>
+    ///     The <see cref="EntityEntry" /> for the entity.
+    /// </summary>
+    public virtual EntityEntry Entry
+        => _entry ??= new EntityEntry(_internalEntityEntry);
+}

src/EFCore/ChangeTracking/DetectedChangesEventArgs.cs

@@ -1,17 +1,15 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-using Microsoft.EntityFrameworkCore.ChangeTracking.Internal;
-
 namespace Microsoft.EntityFrameworkCore.ChangeTracking;
 
 /// <summary>
-///     Event arguments for the <see cref="ChangeTracker.DetectedChanges" /> event.
+///     Event arguments for the <see cref="ChangeTracker.DetectedAllChanges" /> event.
 /// </summary>
 /// <remarks>
 ///     See <see href="https://aka.ms/efcore-docs-state-changes">State changes of entities in EF Core</see> for more information and examples.
 /// </remarks>
-public class DetectedChangesEventArgs : DetectChangesEventArgs
+public class DetectedChangesEventArgs : EventArgs
 {
     /// <summary>
     ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
@@ -20,10 +18,7 @@ public class DetectedChangesEventArgs : DetectChangesEventArgs
     ///     doing so can result in application failures when updating to a new Entity Framework Core release.
     /// </summary>
     [EntityFrameworkInternal]
-    public DetectedChangesEventArgs(
-        InternalEntityEntry? internalEntityEntry,
-        bool changesFound)
-        : base(internalEntityEntry)
+    public DetectedChangesEventArgs(bool changesFound)
     {
         ChangesFound = changesFound;
     }

src/EFCore/ChangeTracking/DetectedEntityChangesEventArgs.cs

@@ -0,0 +1,39 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Microsoft.EntityFrameworkCore.ChangeTracking.Internal;
+
+namespace Microsoft.EntityFrameworkCore.ChangeTracking;
+
+/// <summary>
+///     Event arguments for the <see cref="ChangeTracker.DetectedEntityChanges" /> event.
+/// </summary>
+/// <remarks>
+///     See <see href="https://aka.ms/efcore-docs-state-changes">State changes of entities in EF Core</see> for more information and examples.
+/// </remarks>
+public class DetectedEntityChangesEventArgs : DetectedChangesEventArgs
+{
+    private readonly InternalEntityEntry _internalEntityEntry;
+    private EntityEntry? _entry;
+
+    /// <summary>
+    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+    ///     any release. You should only use it directly in your code with extreme caution and knowing that
+    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+    /// </summary>
+    [EntityFrameworkInternal]
+    public DetectedEntityChangesEventArgs(
+        InternalEntityEntry internalEntityEntry,
+        bool changesFound)
+        : base(changesFound)
+    {
+        _internalEntityEntry = internalEntityEntry;
+    }
+
+    /// <summary>
+    ///     The <see cref="EntityEntry" /> for the entity.
+    /// </summary>
+    public virtual EntityEntry Entry
+        => _entry ??= new EntityEntry(_internalEntityEntry);
+}