Sections support

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

@@ -3,4 +3,18 @@ Microsoft.AspNetCore.Components.ComponentBase.DispatchExceptionAsync(System.Exce
 Microsoft.AspNetCore.Components.RenderHandle.DispatchExceptionAsync(System.Exception! exception) -> System.Threading.Tasks.Task!
 *REMOVED*Microsoft.AspNetCore.Components.NavigationManager.ToAbsoluteUri(string! relativeUri) -> System.Uri!
 Microsoft.AspNetCore.Components.NavigationManager.ToAbsoluteUri(string? relativeUri) -> System.Uri!
+Microsoft.AspNetCore.Components.Sections.SectionContent
+Microsoft.AspNetCore.Components.Sections.SectionContent.ChildContent.get -> Microsoft.AspNetCore.Components.RenderFragment?
+Microsoft.AspNetCore.Components.Sections.SectionContent.ChildContent.set -> void
+Microsoft.AspNetCore.Components.Sections.SectionContent.Dispose() -> void
+Microsoft.AspNetCore.Components.Sections.SectionContent.IsDefaultContent.get -> bool
+Microsoft.AspNetCore.Components.Sections.SectionContent.IsDefaultContent.set -> void
+Microsoft.AspNetCore.Components.Sections.SectionContent.SectionContent() -> void
+Microsoft.AspNetCore.Components.Sections.SectionContent.SectionId.get -> object!
+Microsoft.AspNetCore.Components.Sections.SectionContent.SectionId.set -> void
+Microsoft.AspNetCore.Components.Sections.SectionOutlet
+Microsoft.AspNetCore.Components.Sections.SectionOutlet.Dispose() -> void
+Microsoft.AspNetCore.Components.Sections.SectionOutlet.SectionId.get -> object!
+Microsoft.AspNetCore.Components.Sections.SectionOutlet.SectionId.set -> void
+Microsoft.AspNetCore.Components.Sections.SectionOutlet.SectionOutlet() -> void
 Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder.AddComponentParameter(int sequence, string! name, object? value) -> void

src/Components/Components/src/Sections/SectionContent.cs

@@ -4,18 +4,19 @@
 namespace Microsoft.AspNetCore.Components.Sections;
 
 /// <summary>
-/// Provides content to <see cref="SectionOutlet"/> components with matching <see cref="Name"/>s.
+/// Provides content to <see cref="SectionOutlet"/> components with matching <see cref="SectionId"/>s.
 /// </summary>
-internal sealed class SectionContent : ISectionContentProvider, IComponent, IDisposable
+public sealed class SectionContent : ISectionContentProvider, IComponent, IDisposable
 {
-    private string? _registeredName;
+    private object? _registeredSectionId;
+    private bool? _registeredIsDefaultContent;
     private SectionRegistry _registry = default!;
 
     /// <summary>
-    /// Gets or sets the name that determines which <see cref="SectionOutlet"/> instance will render
+    /// Gets or sets the ID that determines which <see cref="SectionOutlet"/> instance will render
     /// the content of this instance.
     /// </summary>
-    [Parameter] public string Name { get; set; } = default!;
+    [Parameter, EditorRequired] public object SectionId { get; set; } = default!;
 
     /// <summary>
     /// Gets or sets whether this component should provide the default content for the target
@@ -39,33 +40,34 @@ Task IComponent.SetParametersAsync(ParameterView parameters)
     {
         parameters.SetParameterProperties(this);
 
-        if (string.IsNullOrEmpty(Name))
+        if (SectionId is null)
         {
-            throw new InvalidOperationException($"{GetType()} requires a non-empty string parameter '{nameof(Name)}'.");
+            throw new InvalidOperationException($"{nameof(SectionContent)} requires a non-null value for the parameter '{nameof(SectionId)}'.");
         }
 
-        if (Name != _registeredName)
+        if (!object.Equals(SectionId, _registeredSectionId) || IsDefaultContent != _registeredIsDefaultContent)
         {
-            if (_registeredName is not null)
+            if (_registeredSectionId is not null)
             {
-                _registry.RemoveProvider(_registeredName, this);
+                _registry.RemoveProvider(_registeredSectionId, this);
             }
 
-            _registry.AddProvider(Name, this, IsDefaultContent);
-            _registeredName = Name;
+            _registry.AddProvider(SectionId, this, IsDefaultContent);
+            _registeredSectionId = SectionId;
+            _registeredIsDefaultContent = IsDefaultContent;
         }
 
-        _registry.NotifyContentChanged(Name, this);
+        _registry.NotifyContentChanged(SectionId, this);
 
         return Task.CompletedTask;
     }
 
     /// <inheritdoc/>
     public void Dispose()
     {
-        if (_registeredName is not null)
+        if (_registeredSectionId is not null)
         {
-            _registry.RemoveProvider(_registeredName, this);
+            _registry.RemoveProvider(_registeredSectionId, this);
         }
     }
 }

src/Components/Components/src/Sections/SectionOutlet.cs

@@ -4,22 +4,22 @@
 namespace Microsoft.AspNetCore.Components.Sections;
 
 /// <summary>
-/// Renders content provided by <see cref="SectionContent"/> components with matching <see cref="Name"/>s.
+/// Renders content provided by <see cref="SectionContent"/> components with matching <see cref="SectionId"/>s.
 /// </summary>
-internal sealed class SectionOutlet : ISectionContentSubscriber, IComponent, IDisposable
+public sealed class SectionOutlet : ISectionContentSubscriber, IComponent, IDisposable
 {
     private static readonly RenderFragment _emptyRenderFragment = _ => { };
 
-    private string? _subscribedName;
+    private object? _subscribedSectionId;
     private RenderHandle _renderHandle;
     private SectionRegistry _registry = default!;
     private RenderFragment? _content;
 
     /// <summary>
-    /// Gets or sets the name that determines which <see cref="SectionContent"/> instances will provide
+    /// Gets or sets the ID that determines which <see cref="SectionContent"/> instances will provide
     /// content to this instance.
     /// </summary>
-    [Parameter] public string Name { get; set; } = default!;
+    [Parameter, EditorRequired] public object SectionId { get; set; } = default!;
 
     void IComponent.Attach(RenderHandle renderHandle)
     {
@@ -31,20 +31,20 @@ Task IComponent.SetParametersAsync(ParameterView parameters)
     {
         parameters.SetParameterProperties(this);
 
-        if (string.IsNullOrEmpty(Name))
+        if (SectionId is null)
         {
-            throw new InvalidOperationException($"{GetType()} requires a non-empty string parameter '{nameof(Name)}'.");
+            throw new InvalidOperationException($"{nameof(SectionOutlet)} requires a non-null value for the parameter '{nameof(SectionId)}'.");
         }
 
-        if (Name != _subscribedName)
+        if (!object.Equals(SectionId, _subscribedSectionId))
         {
-            if (_subscribedName is not null)
+            if (_subscribedSectionId is not null)
             {
-                _registry.Unsubscribe(_subscribedName);
+                _registry.Unsubscribe(_subscribedSectionId);
             }
 
-            _registry.Subscribe(Name, this);
-            _subscribedName = Name;
+            _registry.Subscribe(SectionId, this);
+            _subscribedSectionId = SectionId;
         }
 
         RenderContent();
@@ -74,9 +74,9 @@ private void RenderContent()
     /// <inheritdoc/>
     public void Dispose()
     {
-        if (_subscribedName is not null)
+        if (_subscribedSectionId is not null)
         {
-            _registry.Unsubscribe(_subscribedName);
+            _registry.Unsubscribe(_subscribedSectionId);
         }
     }
 }

src/Components/Components/src/Sections/SectionRegistry.cs

@@ -5,15 +5,15 @@ namespace Microsoft.AspNetCore.Components.Sections;
 
 internal sealed class SectionRegistry
 {
-    private readonly Dictionary<string, ISectionContentSubscriber> _subscribersByName = new();
-    private readonly Dictionary<string, List<ISectionContentProvider>> _providersByName = new();
+    private readonly Dictionary<object, ISectionContentSubscriber> _subscribersBySectionId = new();
+    private readonly Dictionary<object, List<ISectionContentProvider>> _providersBySectionId = new();
 
-    public void AddProvider(string name, ISectionContentProvider provider, bool isDefaultProvider)
+    public void AddProvider(object sectionId, ISectionContentProvider provider, bool isDefaultProvider)
     {
-        if (!_providersByName.TryGetValue(name, out var providers))
+        if (!_providersBySectionId.TryGetValue(sectionId, out var providers))
         {
             providers = new();
-            _providersByName.Add(name, providers);
+            _providersBySectionId.Add(sectionId, providers);
         }
 
         if (isDefaultProvider)
@@ -26,18 +26,18 @@ public void AddProvider(string name, ISectionContentProvider provider, bool isDe
         }
     }
 
-    public void RemoveProvider(string name, ISectionContentProvider provider)
+    public void RemoveProvider(object sectionId, ISectionContentProvider provider)
     {
-        if (!_providersByName.TryGetValue(name, out var providers))
+        if (!_providersBySectionId.TryGetValue(sectionId, out var providers))
         {
-            throw new InvalidOperationException($"There are no content providers with the name '{name}'.");
+            throw new InvalidOperationException($"There are no content providers with the given section ID.");
         }
 
         var index = providers.LastIndexOf(provider);
 
         if (index < 0)
         {
-            throw new InvalidOperationException($"The provider was not found in the providers list of name '{name}'.");
+            throw new InvalidOperationException($"The provider was not found in the providers list of the given section ID.");
         }
 
         providers.RemoveAt(index);
@@ -47,44 +47,44 @@ public void RemoveProvider(string name, ISectionContentProvider provider)
             // We just removed the most recently added provider, meaning we need to change
             // the current content to that of second most recently added provider.
             var content = GetCurrentProviderContentOrDefault(providers);
-            NotifyContentChangedForSubscriber(name, content);
+            NotifyContentChangedForSubscriber(sectionId, content);
         }
     }
 
-    public void Subscribe(string name, ISectionContentSubscriber subscriber)
+    public void Subscribe(object sectionId, ISectionContentSubscriber subscriber)
     {
-        if (_subscribersByName.ContainsKey(name))
+        if (_subscribersBySectionId.ContainsKey(sectionId))
         {
-            throw new InvalidOperationException($"There is already a subscriber to the content '{name}'.");
+            throw new InvalidOperationException($"There is already a subscriber to the content with the given section ID.");
         }
 
         // Notify the new subscriber with any existing content.
-        var content = GetCurrentProviderContentOrDefault(name);
+        var content = GetCurrentProviderContentOrDefault(sectionId);
         subscriber.ContentChanged(content);
 
-        _subscribersByName.Add(name, subscriber);
+        _subscribersBySectionId.Add(sectionId, subscriber);
     }
 
-    public void Unsubscribe(string name)
+    public void Unsubscribe(object sectionId)
     {
-        if (!_subscribersByName.Remove(name))
+        if (!_subscribersBySectionId.Remove(sectionId))
         {
-            throw new InvalidOperationException($"The subscriber with name '{name}' is already unsubscribed.");
+            throw new InvalidOperationException($"The subscriber with the given section ID is already unsubscribed.");
         }
     }
 
-    public void NotifyContentChanged(string name, ISectionContentProvider provider)
+    public void NotifyContentChanged(object sectionId, ISectionContentProvider provider)
     {
-        if (!_providersByName.TryGetValue(name, out var providers))
+        if (!_providersBySectionId.TryGetValue(sectionId, out var providers))
         {
-            throw new InvalidOperationException($"There are no content providers with the name '{name}'.");
+            throw new InvalidOperationException($"There are no content providers with the given section ID.");
         }
 
         // We only notify content changed for subscribers when the content of the
         // most recently added provider changes.
         if (providers.Count != 0 && providers[^1] == provider)
         {
-            NotifyContentChangedForSubscriber(name, provider.Content);
+            NotifyContentChangedForSubscriber(sectionId, provider.Content);
         }
     }
 
@@ -93,14 +93,14 @@ public void NotifyContentChanged(string name, ISectionContentProvider provider)
             ? providers[^1].Content
             : null;
 
-    private RenderFragment? GetCurrentProviderContentOrDefault(string name)
-        => _providersByName.TryGetValue(name, out var existingList)
+    private RenderFragment? GetCurrentProviderContentOrDefault(object sectionId)
+        => _providersBySectionId.TryGetValue(sectionId, out var existingList)
             ? GetCurrentProviderContentOrDefault(existingList)
             : null;
 
-    private void NotifyContentChangedForSubscriber(string name, RenderFragment? content)
+    private void NotifyContentChangedForSubscriber(object sectionId, RenderFragment? content)
     {
-        if (_subscribersByName.TryGetValue(name, out var subscriber))
+        if (_subscribersBySectionId.TryGetValue(sectionId, out var subscriber))
         {
             subscriber.ContentChanged(content);
         }

src/Components/Web/src/Head/HeadContent.cs

@@ -21,7 +21,7 @@ public sealed class HeadContent : ComponentBase
     protected override void BuildRenderTree(RenderTreeBuilder builder)
     {
         builder.OpenComponent<SectionContent>(0);
-        builder.AddComponentParameter(1, nameof(SectionContent.Name), HeadOutlet.HeadSectionOutletName);
+        builder.AddComponentParameter(1, nameof(SectionContent.SectionId), HeadOutlet.HeadSectionId);
         builder.AddComponentParameter(2, nameof(SectionContent.ChildContent), ChildContent);
         builder.CloseComponent();
     }

src/Components/Web/src/Head/HeadOutlet.cs

@@ -14,8 +14,8 @@ public sealed class HeadOutlet : ComponentBase
 {
     private const string GetAndRemoveExistingTitle = "Blazor._internal.PageTitle.getAndRemoveExistingTitle";
 
-    internal const string HeadSectionOutletName = "head";
-    internal const string TitleSectionOutletName = "title";
+    internal static readonly object HeadSectionId = new();
+    internal static readonly object TitleSectionId = new();
 
     private string? _defaultTitle;
 
@@ -37,22 +37,22 @@ protected override void BuildRenderTree(RenderTreeBuilder builder)
     {
         // Render the title content
         builder.OpenComponent<SectionOutlet>(0);
-        builder.AddComponentParameter(1, nameof(SectionOutlet.Name), TitleSectionOutletName);
+        builder.AddComponentParameter(1, nameof(SectionOutlet.SectionId), TitleSectionId);
         builder.CloseComponent();
 
         // Render the default title if it exists
         if (!string.IsNullOrEmpty(_defaultTitle))
         {
             builder.OpenComponent<SectionContent>(2);
-            builder.AddComponentParameter(3, nameof(SectionContent.Name), TitleSectionOutletName);
+            builder.AddComponentParameter(3, nameof(SectionContent.SectionId), TitleSectionId);
             builder.AddComponentParameter(4, nameof(SectionContent.IsDefaultContent), true);
             builder.AddComponentParameter(5, nameof(SectionContent.ChildContent), (RenderFragment)BuildDefaultTitleRenderTree);
             builder.CloseComponent();
         }
 
         // Render the rest of the head metadata
         builder.OpenComponent<SectionOutlet>(6);
-        builder.AddComponentParameter(7, nameof(SectionOutlet.Name), HeadSectionOutletName);
+        builder.AddComponentParameter(7, nameof(SectionOutlet.SectionId), TitleSectionId);
         builder.CloseComponent();
     }
 

src/Components/Web/src/Head/PageTitle.cs

@@ -21,7 +21,7 @@ public sealed class PageTitle : ComponentBase
     protected override void BuildRenderTree(RenderTreeBuilder builder)
     {
         builder.OpenComponent<SectionContent>(0);
-        builder.AddComponentParameter(1, nameof(SectionContent.Name), HeadOutlet.TitleSectionOutletName);
+        builder.AddComponentParameter(1, nameof(SectionContent.SectionId), HeadOutlet.TitleSectionId);
         builder.AddComponentParameter(2, nameof(SectionContent.ChildContent), (RenderFragment)BuildTitleRenderTree);
         builder.CloseComponent();
     }