Forms behavior clarifications (#49340)

src/Components/Components/src/CascadingParameterState.cs

@@ -7,6 +7,7 @@
 using System.Reflection;
 using Microsoft.AspNetCore.Components.Reflection;
 using Microsoft.AspNetCore.Components.Rendering;
+using Microsoft.AspNetCore.Components.RenderTree;
 using static Microsoft.AspNetCore.Internal.LinkerFlags;
 
 namespace Microsoft.AspNetCore.Components;
@@ -43,7 +44,7 @@ public static IReadOnlyList<CascadingParameterState> FindCascadingParameters(Com
         for (var infoIndex = 0; infoIndex < numInfos; infoIndex++)
         {
             ref var info = ref infos[infoIndex];
-            var supplier = GetMatchingCascadingValueSupplier(info, componentState);
+            var supplier = GetMatchingCascadingValueSupplier(info, componentState.Renderer, componentState.LogicalParentComponentState);
             if (supplier != null)
             {
                 // Although not all parameters might be matched, we know the maximum number
@@ -55,10 +56,10 @@ public static IReadOnlyList<CascadingParameterState> FindCascadingParameters(Com
         return resultStates ?? (IReadOnlyList<CascadingParameterState>)Array.Empty<CascadingParameterState>();
     }
 
-    private static ICascadingValueSupplier? GetMatchingCascadingValueSupplier(in CascadingParameterInfo info, ComponentState componentState)
+    internal static ICascadingValueSupplier? GetMatchingCascadingValueSupplier(in CascadingParameterInfo info, Renderer renderer, ComponentState? componentState)
     {
         // First scan up through the component hierarchy
-        var candidate = componentState.LogicalParentComponentState;
+        var candidate = componentState;
         while (candidate is not null)
         {
             if (candidate.Component is ICascadingValueSupplier valueSupplier && valueSupplier.CanSupplyValue(info))
@@ -70,7 +71,7 @@ public static IReadOnlyList<CascadingParameterState> FindCascadingParameters(Com
         }
 
         // We got to the root and found no match, so now look at the providers registered in DI
-        foreach (var valueSupplier in componentState.Renderer.ServiceProviderCascadingValueSuppliers)
+        foreach (var valueSupplier in renderer.ServiceProviderCascadingValueSuppliers)
         {
             if (valueSupplier.CanSupplyValue(info))
             {

src/Components/Components/src/PublicAPI.Unshipped.txt

@@ -32,15 +32,18 @@ Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder.AddComponentRenderMo
 Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder.AddNamedEvent(int sequence, string! eventType, string! assignedName) -> void
 Microsoft.AspNetCore.Components.RenderTree.ComponentFrameFlags
 Microsoft.AspNetCore.Components.RenderTree.ComponentFrameFlags.HasCallerSpecifiedRenderMode = 1 -> Microsoft.AspNetCore.Components.RenderTree.ComponentFrameFlags
-Microsoft.AspNetCore.Components.RenderTree.NamedEvent
-Microsoft.AspNetCore.Components.RenderTree.NamedEvent.AssignedName.get -> string!
-Microsoft.AspNetCore.Components.RenderTree.NamedEvent.ComponentId.get -> int
-Microsoft.AspNetCore.Components.RenderTree.NamedEvent.EventType.get -> string!
-Microsoft.AspNetCore.Components.RenderTree.NamedEvent.FrameIndex.get -> int
-Microsoft.AspNetCore.Components.RenderTree.NamedEvent.NamedEvent() -> void
-Microsoft.AspNetCore.Components.RenderTree.NamedEvent.NamedEvent(int componentId, int frameIndex, string! eventType, string! assignedName) -> void
-Microsoft.AspNetCore.Components.RenderTree.RenderBatch.AddedNamedEvents.get -> Microsoft.AspNetCore.Components.RenderTree.ArrayRange<Microsoft.AspNetCore.Components.RenderTree.NamedEvent>?
-Microsoft.AspNetCore.Components.RenderTree.RenderBatch.RemovedNamedEvents.get -> Microsoft.AspNetCore.Components.RenderTree.ArrayRange<Microsoft.AspNetCore.Components.RenderTree.NamedEvent>?
+Microsoft.AspNetCore.Components.RenderTree.NamedEventChange
+Microsoft.AspNetCore.Components.RenderTree.NamedEventChange.AssignedName.get -> string!
+Microsoft.AspNetCore.Components.RenderTree.NamedEventChange.ChangeType.get -> Microsoft.AspNetCore.Components.RenderTree.NamedEventChangeType
+Microsoft.AspNetCore.Components.RenderTree.NamedEventChange.ComponentId.get -> int
+Microsoft.AspNetCore.Components.RenderTree.NamedEventChange.EventType.get -> string!
+Microsoft.AspNetCore.Components.RenderTree.NamedEventChange.FrameIndex.get -> int
+Microsoft.AspNetCore.Components.RenderTree.NamedEventChange.NamedEventChange() -> void
+Microsoft.AspNetCore.Components.RenderTree.NamedEventChange.NamedEventChange(Microsoft.AspNetCore.Components.RenderTree.NamedEventChangeType changeType, int componentId, int frameIndex, string! eventType, string! assignedName) -> void
+Microsoft.AspNetCore.Components.RenderTree.NamedEventChangeType
+Microsoft.AspNetCore.Components.RenderTree.NamedEventChangeType.Added = 0 -> Microsoft.AspNetCore.Components.RenderTree.NamedEventChangeType
+Microsoft.AspNetCore.Components.RenderTree.NamedEventChangeType.Removed = 1 -> Microsoft.AspNetCore.Components.RenderTree.NamedEventChangeType
+Microsoft.AspNetCore.Components.RenderTree.RenderBatch.NamedEventChanges.get -> Microsoft.AspNetCore.Components.RenderTree.ArrayRange<Microsoft.AspNetCore.Components.RenderTree.NamedEventChange>?
 Microsoft.AspNetCore.Components.RenderTree.RenderTreeFrame.ComponentFrameFlags.get -> Microsoft.AspNetCore.Components.RenderTree.ComponentFrameFlags
 Microsoft.AspNetCore.Components.RenderTree.RenderTreeFrameType.ComponentRenderMode = 9 -> Microsoft.AspNetCore.Components.RenderTree.RenderTreeFrameType
 Microsoft.AspNetCore.Components.RenderTree.RenderTreeFrameType.NamedEvent = 10 -> Microsoft.AspNetCore.Components.RenderTree.RenderTreeFrameType

src/Components/Components/src/RenderTree/NamedEvent.cs → src/Components/Components/src/RenderTree/NamedEventChange.cs

@@ -8,14 +8,20 @@ namespace Microsoft.AspNetCore.Components.RenderTree;
 /// of the Blazor framework. These types will change in a future release.
 /// </summary>
 /// <remarks>
-/// Constructs an instance of <see cref="NamedEvent"/>.
+/// Constructs an instance of <see cref="NamedEventChange"/>.
 /// </remarks>
+/// <param name="changeType">The type of the change.</param>
 /// <param name="componentId">The ID of the component holding the named value.</param>
 /// <param name="frameIndex">The index of the <see cref="RenderTreeFrameType.NamedEvent"/> frame within the component's current render output.</param>
 /// <param name="eventType">The event type.</param>
 /// <param name="assignedName">The application-assigned name.</param>
-public readonly struct NamedEvent(int componentId, int frameIndex, string eventType, string assignedName)
+public readonly struct NamedEventChange(NamedEventChangeType changeType, int componentId, int frameIndex, string eventType, string assignedName)
 {
+    /// <summary>
+    /// Describes the type of the change.
+    /// </summary>
+    public readonly NamedEventChangeType ChangeType { get; } = changeType;
+
     /// <summary>
     /// The ID of the component holding the named event.
     /// </summary>

src/Components/Components/src/RenderTree/NamedEventChangeType.cs

@@ -0,0 +1,20 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace Microsoft.AspNetCore.Components.RenderTree;
+
+/// <summary>
+/// Describes a change to a named event.
+/// </summary>
+public enum NamedEventChangeType : int
+{
+    /// <summary>
+    /// Indicates that the item was added.
+    /// </summary>
+    Added,
+
+    /// <summary>
+    /// Indicates that the item was removed.
+    /// </summary>
+    Removed,
+}

src/Components/Components/src/RenderTree/RenderBatch.cs

@@ -34,29 +34,22 @@ public readonly struct RenderBatch
     public ArrayRange<ulong> DisposedEventHandlerIDs { get; }
 
     /// <summary>
-    /// Gets the named events that were added, or null.
+    /// Gets the named events that were changed, or null.
     /// </summary>
-    public ArrayRange<NamedEvent>? AddedNamedEvents { get; }
-
-    /// <summary>
-    /// Gets the named events that were removed, or null.
-    /// </summary>
-    public ArrayRange<NamedEvent>? RemovedNamedEvents { get; }
+    public ArrayRange<NamedEventChange>? NamedEventChanges { get; }
 
     internal RenderBatch(
         ArrayRange<RenderTreeDiff> updatedComponents,
         ArrayRange<RenderTreeFrame> referenceFrames,
         ArrayRange<int> disposedComponentIDs,
         ArrayRange<ulong> disposedEventHandlerIDs,
-        ArrayRange<NamedEvent>? addedNamedEvents,
-        ArrayRange<NamedEvent>? removedNamedEvents)
+        ArrayRange<NamedEventChange>? changedNamedEvents)
     {
         UpdatedComponents = updatedComponents;
         ReferenceFrames = referenceFrames;
         DisposedComponentIDs = disposedComponentIDs;
         DisposedEventHandlerIDs = disposedEventHandlerIDs;
-        AddedNamedEvents = addedNamedEvents;
-        RemovedNamedEvents = removedNamedEvents;
+        NamedEventChanges = changedNamedEvents;
     }
 }
 

src/Components/Components/src/Rendering/RenderBatchBuilder.cs

@@ -22,8 +22,7 @@ internal sealed class RenderBatchBuilder : IDisposable
     public ArrayBuilder<RenderTreeDiff> UpdatedComponentDiffs { get; } = new ArrayBuilder<RenderTreeDiff>();
     public ArrayBuilder<int> DisposedComponentIds { get; } = new ArrayBuilder<int>();
     public ArrayBuilder<ulong> DisposedEventHandlerIds { get; } = new ArrayBuilder<ulong>();
-    public ArrayBuilder<NamedEvent>? AddedNamedEvents;
-    public ArrayBuilder<NamedEvent>? RemovedNamedEvents;
+    public ArrayBuilder<NamedEventChange>? NamedEventChanges;
 
     // Buffers referenced by UpdatedComponentDiffs
     public ArrayBuilder<RenderTreeEdit> EditsBuffer { get; } = new ArrayBuilder<RenderTreeEdit>(64);
@@ -56,8 +55,7 @@ public void ClearStateForCurrentBatch()
         DisposedComponentIds.Clear();
         DisposedEventHandlerIds.Clear();
         AttributeDiffSet.Clear();
-        AddedNamedEvents?.Clear();
-        RemovedNamedEvents?.Clear();
+        NamedEventChanges?.Clear();
     }
 
     public RenderBatch ToBatch()
@@ -66,8 +64,7 @@ public RenderBatch ToBatch()
             ReferenceFramesBuffer.ToRange(),
             DisposedComponentIds.ToRange(),
             DisposedEventHandlerIds.ToRange(),
-            AddedNamedEvents?.ToRange(),
-            RemovedNamedEvents?.ToRange());
+            NamedEventChanges?.ToRange());
 
     public void InvalidateParameterViews()
     {
@@ -87,14 +84,14 @@ public void InvalidateParameterViews()
 
     public void AddNamedEvent(int componentId, int frameIndex, ref RenderTreeFrame frame)
     {
-        AddedNamedEvents ??= new();
-        AddedNamedEvents.Append(new NamedEvent(componentId, frameIndex, frame.NamedEventType, frame.NamedEventAssignedName));
+        NamedEventChanges ??= new();
+        NamedEventChanges.Append(new NamedEventChange(NamedEventChangeType.Added, componentId, frameIndex, frame.NamedEventType, frame.NamedEventAssignedName));
     }
 
     public void RemoveNamedEvent(int componentId, int frameIndex, ref RenderTreeFrame frame)
     {
-        RemovedNamedEvents ??= new();
-        RemovedNamedEvents.Append(new NamedEvent(componentId, frameIndex, frame.NamedEventType, frame.NamedEventAssignedName));
+        NamedEventChanges ??= new();
+        NamedEventChanges.Append(new NamedEventChange(NamedEventChangeType.Removed, componentId, frameIndex, frame.NamedEventType, frame.NamedEventAssignedName));
     }
 
     public void Dispose()
@@ -104,7 +101,6 @@ public void Dispose()
         UpdatedComponentDiffs.Dispose();
         DisposedComponentIds.Dispose();
         DisposedEventHandlerIds.Dispose();
-        AddedNamedEvents?.Dispose();
-        RemovedNamedEvents?.Dispose();
+        NamedEventChanges?.Dispose();
     }
 }

src/Components/Components/src/Rendering/RenderTreeBuilder.cs

@@ -28,7 +28,7 @@ public sealed class RenderTreeBuilder : IDisposable
     private bool _hasSeenAddMultipleAttributes;
     private Dictionary<string, int>? _seenAttributeNames;
     private IComponentRenderMode? _pendingComponentCallSiteRenderMode; // TODO: Remove when Razor compiler supports call-site @rendermode
-    private (int Sequence, string AssignedName)? _pendingNamedSubmitEvent; // TODO: Remove when Razor compiler supports @onsubmit:name
+    private (int Sequence, string AssignedName)? _pendingNamedSubmitEvent; // TODO: Remove when Razor compiler supports @formname
 
     /// <summary>
     /// The reserved parameter name used for supplying child content.
@@ -80,7 +80,7 @@ public void CloseElement()
         _entries.Buffer[indexOfEntryBeingClosed].ElementSubtreeLengthField = _entries.Count - indexOfEntryBeingClosed;
     }
 
-    // TODO: Remove this once Razor supports @onsubmit:name
+    // TODO: Remove this once Razor supports @formname
     private void CompletePendingNamedSubmitEvent()
     {
         if (_pendingNamedSubmitEvent is { } pendingNamedSubmitEvent)
@@ -237,9 +237,9 @@ public void AddAttribute(int sequence, string name, string? value)
         AssertCanAddAttribute();
         if (value != null || _lastNonAttributeFrameType == RenderTreeFrameType.Component)
         {
-            // TODO: Remove this once the Razor compiler is updated to support @onsubmit:name
-            // That should compile directly as a call to AddNamedValue.
-            if (string.Equals(name, "@onsubmit:name", StringComparison.Ordinal) && _lastNonAttributeFrameType == RenderTreeFrameType.Element)
+            // TODO: Remove this once the Razor compiler is updated to support @formname
+            // That should compile directly as a call to AddNamedEvent.
+            if (string.Equals(name, "@formname", StringComparison.Ordinal) && _lastNonAttributeFrameType == RenderTreeFrameType.Element)
             {
                 _pendingNamedSubmitEvent = (sequence, value!);
             }
@@ -722,7 +722,7 @@ public void AddComponentRenderMode(int sequence, IComponentRenderMode renderMode
     public void AddNamedEvent(int sequence, string eventType, string assignedName)
     {
         ArgumentNullException.ThrowIfNull(eventType);
-        ArgumentNullException.ThrowIfNull(assignedName);
+        ArgumentException.ThrowIfNullOrEmpty(assignedName);
 
         // Note that we could trivially extend this to a generic concept of "named values" that exist within the rendertree
         // and are tracked when added, removed, or updated. Currently we don't need that generality, but if we ever do, we

src/Components/Components/test/RenderTreeDiffBuilderTest.cs

@@ -2237,10 +2237,9 @@ public void RecognizesNamedEventBeingAdded()
                 Assert.Equal(0, entry.ReferenceFrameIndex);
                 Assert.Equal("new element", referenceFrames[entry.ReferenceFrameIndex].ElementName);
             });
-        Assert.Collection(batch.AddedNamedEvents.Value.AsEnumerable(),
-            entry => AssertNamedEvent(entry, 123, 2, "someevent1", "added to existing element"),
-            entry => AssertNamedEvent(entry, 123, 4, "someevent2", "added with new element"));
-        Assert.False(batch.RemovedNamedEvents.HasValue);
+        Assert.Collection(batch.NamedEventChanges.Value.AsEnumerable(),
+            entry => AssertNamedEventChange(entry, NamedEventChangeType.Added, 123, 2, "someevent1", "added to existing element"),
+            entry => AssertNamedEventChange(entry, NamedEventChangeType.Added, 123, 4, "someevent2", "added with new element"));
     }
 
     [Fact]
@@ -2264,10 +2263,9 @@ public void RecognizesNamedEventBeingRemoved()
         // Assert
         Assert.Collection(result.Edits,
             entry => AssertEdit(entry, RenderTreeEditType.RemoveFrame, 1));
-        Assert.False(batch.AddedNamedEvents.HasValue);
-        Assert.Collection(batch.RemovedNamedEvents.Value.AsEnumerable(),
-            entry => AssertNamedEvent(entry, 123, 2, "someevent1", "removing from retained element"),
-            entry => AssertNamedEvent(entry, 123, 4, "someevent2", "removed because element was removed"));
+        Assert.Collection(batch.NamedEventChanges.Value.AsEnumerable(),
+            entry => AssertNamedEventChange(entry, NamedEventChangeType.Removed, 123, 2, "someevent1", "removing from retained element"),
+            entry => AssertNamedEventChange(entry, NamedEventChangeType.Removed, 123, 4, "someevent2", "removed because element was removed"));
     }
 
     [Fact]
@@ -2293,10 +2291,9 @@ public void RecognizesNamedEventBeingMoved()
                 Assert.Equal(0, entry.ReferenceFrameIndex);
                 Assert.Equal("attr1", referenceFrames[entry.ReferenceFrameIndex].AttributeName);
             });
-        Assert.Collection(batch.RemovedNamedEvents.Value.AsEnumerable(),
-            entry => AssertNamedEvent(entry, 123, 1, "eventname", "assigned name"));
-        Assert.Collection(batch.AddedNamedEvents.Value.AsEnumerable(),
-            entry => AssertNamedEvent(entry, 123, 2, "eventname", "assigned name"));
+        Assert.Collection(batch.NamedEventChanges.Value.AsEnumerable(),
+            entry => AssertNamedEventChange(entry, NamedEventChangeType.Removed, 123, 1, "eventname", "assigned name"),
+            entry => AssertNamedEventChange(entry, NamedEventChangeType.Added, 123, 2, "eventname", "assigned name"));
     }
 
     [Fact]
@@ -2317,10 +2314,9 @@ public void RecognizesNamedEventChangingAssignedName()
 
         // Assert
         Assert.Empty(result.Edits);
-        Assert.Collection(batch.RemovedNamedEvents.Value.AsEnumerable(),
-            entry => AssertNamedEvent(entry, 123, 1, "eventname1", "original name"));
-        Assert.Collection(batch.AddedNamedEvents.Value.AsEnumerable(),
-            entry => AssertNamedEvent(entry, 123, 1, "eventname1", "changed name"));
+        Assert.Collection(batch.NamedEventChanges.Value.AsEnumerable(),
+            entry => AssertNamedEventChange(entry, NamedEventChangeType.Removed, 123, 1, "eventname1", "original name"),
+            entry => AssertNamedEventChange(entry, NamedEventChangeType.Added, 123, 1, "eventname1", "changed name"));
     }
 
     private (RenderTreeDiff, RenderTreeFrame[]) GetSingleUpdatedComponent(bool initializeFromFrames = false)
@@ -2486,13 +2482,15 @@ private static void AssertPermutationListEntry(
         Assert.Equal(toSiblingIndex, edit.MoveToSiblingIndex);
     }
 
-    private static void AssertNamedEvent(
-        NamedEvent namedEvent,
+    private static void AssertNamedEventChange(
+        NamedEventChange namedEvent,
+        NamedEventChangeType type,
         int componentId,
         int frameIndex,
         string eventType,
         string assignedName)
     {
+        Assert.Equal(type, namedEvent.ChangeType);
         Assert.Equal(componentId, namedEvent.ComponentId);
         Assert.Equal(frameIndex, namedEvent.FrameIndex);
         Assert.Equal(eventType, namedEvent.EventType);

src/Components/Components/test/Rendering/RenderTreeBuilderTest.cs

@@ -2270,6 +2270,21 @@ public void CannotAddNamedEventWithNullAssignedName()
         Assert.Equal("assignedName", ex.ParamName);
     }
 
+    [Fact]
+    public void CannotAddNamedEventWithEmptyAssignedName()
+    {
+        // Arrange
+        var builder = new RenderTreeBuilder();
+        builder.OpenElement(0, "elem");
+
+        // Act/Assert
+        var ex = Assert.Throws<ArgumentException>(() =>
+        {
+            builder.AddNamedEvent(1, "eventtype", "");
+        });
+        Assert.Equal("assignedName", ex.ParamName);
+    }
+
     [Fact]
     public void CannotAddAttributesAfterNamedEvent()
     {
@@ -2287,9 +2302,9 @@ public void CannotAddAttributesAfterNamedEvent()
     }
 
     [Fact]
-    public void TemporaryApiForNamedSubmitEventsWorksEvenIfAttributesAddedAfter()
+    public void TemporaryApiForFormNameEventsWorksEvenIfAttributesAddedAfter()
     {
-        // TODO: Remove this once the Razor compiler is updated to support @onsubmit:name directly
+        // TODO: Remove this once the Razor compiler is updated to support @formname directly
 
         // Arrange
         var builder = new RenderTreeBuilder();
@@ -2298,7 +2313,7 @@ public void TemporaryApiForNamedSubmitEventsWorksEvenIfAttributesAddedAfter()
         // Act
         builder.OpenElement(0, "div");
         builder.AddAttribute(1, "attr1", 123);
-        builder.AddAttribute(2, "@onsubmit:name", "some custom name");
+        builder.AddAttribute(2, "@formname", "some custom name");
         builder.AddAttribute(3, "attr2", 456);
         builder.OpenElement(4, "other");
         builder.CloseElement();