InputRadio component with form support

src/Components/Web/ref/Microsoft.AspNetCore.Components.Web.netcoreapp.cs

@@ -100,7 +100,15 @@ protected override void BuildRenderTree(Microsoft.AspNetCore.Components.Renderin
         protected override string? FormatValueAsString([System.Diagnostics.CodeAnalysis.AllowNullAttribute] TValue value) { throw null; }
         protected override bool TryParseValueFromString(string? value, [System.Diagnostics.CodeAnalysis.MaybeNullAttribute] out TValue result, [System.Diagnostics.CodeAnalysis.NotNullWhenAttribute(false)] out string? validationErrorMessage) { throw null; }
     }
-    public partial class InputRadioGroup : Microsoft.AspNetCore.Components.ComponentBase
+    public partial class InputRadioContext
+    {
+        public InputRadioContext(Microsoft.AspNetCore.Components.Forms.InputRadioContext? parentContext, string groupName, object? currentValue, Microsoft.AspNetCore.Components.EventCallback<Microsoft.AspNetCore.Components.ChangeEventArgs> changeEventCallback) { }
+        public Microsoft.AspNetCore.Components.EventCallback<Microsoft.AspNetCore.Components.ChangeEventArgs> ChangeEventCallback { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } }
+        public object? CurrentValue { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } }
+        public string GroupName { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } }
+        public Microsoft.AspNetCore.Components.Forms.InputRadioContext? FindContextInAncestors(string groupName) { throw null; }
+    }
+    public partial class InputRadioGroup<TValue> : Microsoft.AspNetCore.Components.Forms.InputBase<TValue>
     {
         public InputRadioGroup() { }
         [Microsoft.AspNetCore.Components.ParameterAttribute]
@@ -109,18 +117,22 @@ public InputRadioGroup() { }
         public string? Name { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
         protected override void BuildRenderTree(Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder builder) { }
         protected override void OnParametersSet() { }
+        protected override bool TryParseValueFromString(string? value, [System.Diagnostics.CodeAnalysis.MaybeNullAttribute] out TValue result, [System.Diagnostics.CodeAnalysis.NotNullWhenAttribute(false)] out string? validationErrorMessage) { throw null; }
     }
-    public partial class InputRadio<TValue> : Microsoft.AspNetCore.Components.Forms.InputBase<TValue>
+    public partial class InputRadio<TValue> : Microsoft.AspNetCore.Components.ComponentBase
     {
         public InputRadio() { }
-        protected string? GroupName { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } }
+        [Microsoft.AspNetCore.Components.ParameterAttribute(CaptureUnmatchedValues=true)]
+        public System.Collections.Generic.IReadOnlyDictionary<string, object>? AdditionalAttributes { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
+        protected Microsoft.AspNetCore.Components.Forms.InputRadioContext? Context { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } }
+        [Microsoft.AspNetCore.Components.ParameterAttribute]
+        public string? Name { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
         [Microsoft.AspNetCore.Components.ParameterAttribute]
         [System.Diagnostics.CodeAnalysis.MaybeNullAttribute]
         [System.Diagnostics.CodeAnalysis.AllowNullAttribute]
-        public TValue SelectedValue { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
+        public TValue Value { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
         protected override void BuildRenderTree(Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder builder) { }
         protected override void OnParametersSet() { }
-        protected override bool TryParseValueFromString(string? value, [System.Diagnostics.CodeAnalysis.MaybeNullAttribute] out TValue result, [System.Diagnostics.CodeAnalysis.NotNullWhenAttribute(false)] out string? validationErrorMessage) { throw null; }
     }
     public partial class InputSelect<TValue> : Microsoft.AspNetCore.Components.Forms.InputBase<TValue>
     {

src/Components/Web/ref/Microsoft.AspNetCore.Components.Web.netstandard2.0.cs

@@ -96,7 +96,15 @@ protected override void BuildRenderTree(Microsoft.AspNetCore.Components.Renderin
         protected override string? FormatValueAsString(TValue value) { throw null; }
         protected override bool TryParseValueFromString(string? value, out TValue result, out string? validationErrorMessage) { throw null; }
     }
-    public partial class InputRadioGroup : Microsoft.AspNetCore.Components.ComponentBase
+    public partial class InputRadioContext
+    {
+        public InputRadioContext(Microsoft.AspNetCore.Components.Forms.InputRadioContext? parentContext, string groupName, object? currentValue, Microsoft.AspNetCore.Components.EventCallback<Microsoft.AspNetCore.Components.ChangeEventArgs> changeEventCallback) { }
+        public Microsoft.AspNetCore.Components.EventCallback<Microsoft.AspNetCore.Components.ChangeEventArgs> ChangeEventCallback { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } }
+        public object? CurrentValue { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } }
+        public string GroupName { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } }
+        public Microsoft.AspNetCore.Components.Forms.InputRadioContext? FindContextInAncestors(string groupName) { throw null; }
+    }
+    public partial class InputRadioGroup<TValue> : Microsoft.AspNetCore.Components.Forms.InputBase<TValue>
     {
         public InputRadioGroup() { }
         [Microsoft.AspNetCore.Components.ParameterAttribute]
@@ -105,16 +113,20 @@ public InputRadioGroup() { }
         public string? Name { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
         protected override void BuildRenderTree(Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder builder) { }
         protected override void OnParametersSet() { }
+        protected override bool TryParseValueFromString(string? value, out TValue result, out string? validationErrorMessage) { throw null; }
     }
-    public partial class InputRadio<TValue> : Microsoft.AspNetCore.Components.Forms.InputBase<TValue>
+    public partial class InputRadio<TValue> : Microsoft.AspNetCore.Components.ComponentBase
     {
         public InputRadio() { }
-        protected string? GroupName { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } }
+        [Microsoft.AspNetCore.Components.ParameterAttribute(CaptureUnmatchedValues=true)]
+        public System.Collections.Generic.IReadOnlyDictionary<string, object>? AdditionalAttributes { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
+        protected Microsoft.AspNetCore.Components.Forms.InputRadioContext? Context { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } }
         [Microsoft.AspNetCore.Components.ParameterAttribute]
-        public TValue SelectedValue { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
+        public string? Name { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
+        [Microsoft.AspNetCore.Components.ParameterAttribute]
+        public TValue Value { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
         protected override void BuildRenderTree(Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder builder) { }
         protected override void OnParametersSet() { }
-        protected override bool TryParseValueFromString(string? value, out TValue result, out string? validationErrorMessage) { throw null; }
     }
     public partial class InputSelect<TValue> : Microsoft.AspNetCore.Components.Forms.InputBase<TValue>
     {

src/Components/Web/src/Forms/InputRadio.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Collections.Generic;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using Microsoft.AspNetCore.Components.Rendering;
@@ -11,58 +12,58 @@ namespace Microsoft.AspNetCore.Components.Forms
     /// <summary>
     /// An input component used for selecting a value from a group of choices.
     /// </summary>
-    public class InputRadio<TValue> : InputBase<TValue>
+    public class InputRadio<TValue> : ComponentBase
     {
         /// <summary>
-        /// Gets the name of this <see cref="InputRadio{TValue}"/> group.
+        /// Gets context for this <see cref="InputRadio{TValue}"/>.
         /// </summary>
-        protected string? GroupName { get; private set; }
+        protected InputRadioContext? Context { get; private set; }
 
         /// <summary>
-        /// Gets or sets the value that will be bound when this radio input is selected.
+        /// Gets or sets a collection of additional attributes that will be applied to the input element.
+        /// </summary>
+        [Parameter(CaptureUnmatchedValues = true)] public IReadOnlyDictionary<string, object>? AdditionalAttributes { get; set; }
+
+        /// <summary>
+        /// Gets or sets the value of this input.
         /// </summary>
         [AllowNull]
         [MaybeNull]
         [Parameter]
-        public TValue SelectedValue { get; set; } = default;
+        public TValue Value { get; set; } = default;
 
         /// <summary>
-        /// Gets or sets group name inherited from an ancestor <see cref="InputRadioGroup"/>.
+        /// Gets or sets the name of the parent input radio group.
         /// </summary>
-        [CascadingParameter] InputRadioGroup? CascadedRadioGroup { get; set; }
+        [Parameter] public string? Name { get; set; }
+
+        [CascadingParameter] private InputRadioContext? CascadedContext { get; set; }
 
         /// <inheritdoc />
         protected override void OnParametersSet()
         {
-            GroupName = AdditionalAttributes != null && AdditionalAttributes.TryGetValue("name", out var nameAttribute) ?
-                nameAttribute as string :
-                CascadedRadioGroup?.GroupName;
+            Context = string.IsNullOrEmpty(Name) ? CascadedContext : CascadedContext?.FindContextInAncestors(Name);
 
-            if (string.IsNullOrEmpty(GroupName))
+            if (Context == null)
             {
-                throw new InvalidOperationException($"{GetType()} requires either an explicit string attribute 'name' or " +
-                    $"an ancestor {nameof(InputRadioGroup)}.");
+                throw new InvalidOperationException($"{GetType()} must have an ancestor {typeof(InputRadioGroup<TValue>)} " +
+                    $"with a matching 'Name' property, if specified.");
             }
         }
 
         /// <inheritdoc />
         protected override void BuildRenderTree(RenderTreeBuilder builder)
         {
-            Debug.Assert(GroupName != null);
+            Debug.Assert(Context != null);
 
             builder.OpenElement(0, "input");
             builder.AddMultipleAttributes(1, AdditionalAttributes);
             builder.AddAttribute(2, "type", "radio");
-            builder.AddAttribute(3, "class", CssClass);
-            builder.AddAttribute(4, "name", GroupName);
-            builder.AddAttribute(5, "value", BindConverter.FormatValue(FormatValueAsString(SelectedValue)));
-            builder.AddAttribute(6, "checked", SelectedValue?.Equals(CurrentValue));
-            builder.AddAttribute(7, "onchange", EventCallback.Factory.CreateBinder<string?>(this, __value => CurrentValueAsString = __value, CurrentValueAsString));
+            builder.AddAttribute(3, "name", Context.GroupName);
+            builder.AddAttribute(4, "value", BindConverter.FormatValue(Value?.ToString()));
+            builder.AddAttribute(5, "checked", Context.CurrentValue?.Equals(Value));
+            builder.AddAttribute(6, "onchange", Context.ChangeEventCallback!);
             builder.CloseElement();
         }
-
-        /// <inheritdoc />
-        protected override bool TryParseValueFromString(string? value, [MaybeNull] out TValue result, [NotNullWhen(false)] out string? validationErrorMessage)
-            => this.TryParseSelectableValueFromString(value, out result, out validationErrorMessage);
     }
 }

src/Components/Web/src/Forms/InputRadioContext.cs

@@ -0,0 +1,56 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.AspNetCore.Components.Forms
+{
+    /// <summary>
+    /// Describes context for an <see cref="InputRadio{TValue}"/> component.
+    /// </summary>
+    public class InputRadioContext
+    {
+        private readonly InputRadioContext? _parentContext;
+
+        /// <summary>
+        /// Gets the name of the input radio group.
+        /// </summary>
+        public string GroupName { get; } 
+
+        /// <summary>
+        /// Gets the current selected value in the input radio group.
+        /// </summary>
+        public object? CurrentValue { get; }
+
+        /// <summary>
+        /// Gets the event callback to be invoked when the selected value is changed.
+        /// </summary>
+        public EventCallback<ChangeEventArgs> ChangeEventCallback { get; }
+
+        /// <summary>
+        /// Instantiates a new <see cref="InputRadioContext" />.
+        /// </summary>
+        /// <param name="parentContext">The parent <see cref="InputRadioContext" />.</param>
+        /// <param name="groupName">The name of the input radio group.</param>
+        /// <param name="currentValue">The current selected value in the input radio group.</param>
+        /// <param name="changeEventCallback">The event callback to be invoked when the selected value is changed.</param>
+        public InputRadioContext(
+            InputRadioContext? parentContext,
+            string groupName,
+            object? currentValue,
+            EventCallback<ChangeEventArgs> changeEventCallback)
+        {
+            _parentContext = parentContext;
+
+            GroupName = groupName;
+            CurrentValue = currentValue;
+            ChangeEventCallback = changeEventCallback;
+        }
+
+        /// <summary>
+        /// Finds an <see cref="InputRadioContext"/> in the context's ancestors with the matching <paramref name="groupName"/>.
+        /// </summary>
+        /// <param name="groupName">The group name of the ancestor <see cref="InputRadioContext"/>.</param>
+        /// <returns>The <see cref="InputRadioContext"/>, or <c>null</c> if none was found.</returns>
+        public InputRadioContext? FindContextInAncestors(string groupName)
+            => string.Equals(GroupName, groupName) ? this : _parentContext?.FindContextInAncestors(groupName);
+    }
+}

src/Components/Web/src/Forms/InputRadioGroup.cs

@@ -3,21 +3,21 @@
 
 using System;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using Microsoft.AspNetCore.Components.Rendering;
 
 namespace Microsoft.AspNetCore.Components.Forms
 {
     /// <summary>
     /// Groups child <see cref="InputRadio{TValue}"/> components.
     /// </summary>
-    public class InputRadioGroup : ComponentBase
+    public class InputRadioGroup<TValue> : InputBase<TValue>
     {
         private readonly string _defaultGroupName = Guid.NewGuid().ToString("N");
-
-        internal string? GroupName { get; private set; }
+        private InputRadioContext? _context;
 
         /// <summary>
-        /// Gets or sets the child content to be rendering inside the <see cref="InputRadioGroup"/>.
+        /// Gets or sets the child content to be rendering inside the <see cref="InputRadioGroup{TValue}"/>.
         /// </summary>
         [Parameter] public RenderFragment? ChildContent { get; set; }
 
@@ -26,22 +26,35 @@ public class InputRadioGroup : ComponentBase
         /// </summary>
         [Parameter] public string? Name { get; set; }
 
+        [CascadingParameter] private InputRadioContext? CascadedContext { get; set; }
+
         /// <inheritdoc />
         protected override void OnParametersSet()
         {
-            GroupName = !string.IsNullOrEmpty(Name) ? Name : _defaultGroupName;
+            var changeEventCallback = EventCallback.Factory.CreateBinder<string?>(this, __value => CurrentValueAsString = __value, CurrentValueAsString);
+            var groupName = !string.IsNullOrEmpty(Name) ? Name : _defaultGroupName;
+
+            _context = new InputRadioContext(CascadedContext, groupName, CurrentValue, changeEventCallback);
         }
 
         /// <inheritdoc />
         protected override void BuildRenderTree(RenderTreeBuilder builder)
         {
-            Debug.Assert(GroupName != null);
-
-            builder.OpenComponent<CascadingValue<InputRadioGroup>>(0);
-            builder.AddAttribute(1, "IsFixed", true);
-            builder.AddAttribute(2, "Value", this);
-            builder.AddAttribute(3, "ChildContent", ChildContent);
+            Debug.Assert(_context != null);
+
+            builder.OpenElement(0, "div");
+            builder.AddMultipleAttributes(1, AdditionalAttributes);
+            builder.AddAttribute(2, "class", CssClass);
+            builder.OpenComponent<CascadingValue<InputRadioContext>>(3);
+            builder.AddAttribute(4, "IsFixed", true);
+            builder.AddAttribute(5, "Value", _context);
+            builder.AddAttribute(6, "ChildContent", ChildContent);
             builder.CloseComponent();
+            builder.CloseElement();
         }
+
+        /// <inheritdoc />
+        protected override bool TryParseValueFromString(string? value, [MaybeNull] out TValue result, [NotNullWhen(false)] out string? validationErrorMessage)
+            => this.TryParseSelectableValueFromString(value, out result, out validationErrorMessage);
     }
 }