InputRadio component with form support

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

@@ -61,7 +61,7 @@ protected InputBase() { }
         protected TValue CurrentValue { get { throw null; } set { } }
         protected string? CurrentValueAsString { get { throw null; } set { } }
         protected Microsoft.AspNetCore.Components.Forms.EditContext EditContext { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
-        protected Microsoft.AspNetCore.Components.Forms.FieldIdentifier FieldIdentifier { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
+        protected internal Microsoft.AspNetCore.Components.Forms.FieldIdentifier FieldIdentifier { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
         [Microsoft.AspNetCore.Components.ParameterAttribute]
         [System.Diagnostics.CodeAnalysis.MaybeNullAttribute]
         [System.Diagnostics.CodeAnalysis.AllowNullAttribute]
@@ -71,7 +71,7 @@ protected InputBase() { }
         [Microsoft.AspNetCore.Components.ParameterAttribute]
         public System.Linq.Expressions.Expression<System.Func<TValue>>? ValueExpression { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
         protected virtual void Dispose(bool disposing) { }
-        protected virtual string? FormatValueAsString(TValue value) { throw null; }
+        protected virtual string? FormatValueAsString([System.Diagnostics.CodeAnalysis.AllowNullAttribute] TValue value) { throw null; }
         public override System.Threading.Tasks.Task SetParametersAsync(Microsoft.AspNetCore.Components.ParameterView parameters) { throw null; }
         void System.IDisposable.Dispose() { }
         protected abstract bool TryParseValueFromString(string? value, [System.Diagnostics.CodeAnalysis.MaybeNullAttribute] out TValue result, [System.Diagnostics.CodeAnalysis.NotNullWhenAttribute(false)] out string? validationErrorMessage);
@@ -88,7 +88,7 @@ public InputDate() { }
         [Microsoft.AspNetCore.Components.ParameterAttribute]
         public string ParsingErrorMessage { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
         protected override void BuildRenderTree(Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder builder) { }
-        protected override string FormatValueAsString(TValue value) { throw null; }
+        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 InputNumber<TValue> : Microsoft.AspNetCore.Components.Forms.InputBase<TValue>
@@ -97,9 +97,34 @@ public InputNumber() { }
         [Microsoft.AspNetCore.Components.ParameterAttribute]
         public string ParsingErrorMessage { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
         protected override void BuildRenderTree(Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder builder) { }
-        protected override string? FormatValueAsString(TValue value) { throw null; }
+        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<TValue> : Microsoft.AspNetCore.Components.Forms.InputBase<TValue>
+    {
+        public InputRadioGroup() { }
+        [Microsoft.AspNetCore.Components.ParameterAttribute]
+        public Microsoft.AspNetCore.Components.RenderFragment? ChildContent { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
+        [Microsoft.AspNetCore.Components.ParameterAttribute]
+        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.ComponentBase
+    {
+        public InputRadio() { }
+        [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 { } }
+        [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 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() { }
+    }
     public partial class InputSelect<TValue> : Microsoft.AspNetCore.Components.Forms.InputBase<TValue>
     {
         public InputSelect() { }

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

@@ -59,7 +59,7 @@ protected InputBase() { }
         protected TValue CurrentValue { get { throw null; } set { } }
         protected string? CurrentValueAsString { get { throw null; } set { } }
         protected Microsoft.AspNetCore.Components.Forms.EditContext EditContext { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
-        protected Microsoft.AspNetCore.Components.Forms.FieldIdentifier FieldIdentifier { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
+        protected internal Microsoft.AspNetCore.Components.Forms.FieldIdentifier FieldIdentifier { [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 { } }
         [Microsoft.AspNetCore.Components.ParameterAttribute]
@@ -96,6 +96,29 @@ 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<TValue> : Microsoft.AspNetCore.Components.Forms.InputBase<TValue>
+    {
+        public InputRadioGroup() { }
+        [Microsoft.AspNetCore.Components.ParameterAttribute]
+        public Microsoft.AspNetCore.Components.RenderFragment? ChildContent { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
+        [Microsoft.AspNetCore.Components.ParameterAttribute]
+        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.ComponentBase
+    {
+        public InputRadio() { }
+        [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 { } }
+        [Microsoft.AspNetCore.Components.ParameterAttribute]
+        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() { }
+    }
     public partial class InputSelect<TValue> : Microsoft.AspNetCore.Components.Forms.InputBase<TValue>
     {
         public InputSelect() { }

src/Components/Web/src/Forms/InputBase.cs

@@ -58,7 +58,7 @@ public abstract class InputBase<TValue> : ComponentBase, IDisposable
         /// <summary>
         /// Gets the <see cref="FieldIdentifier"/> for the bound value.
         /// </summary>
-        protected FieldIdentifier FieldIdentifier { get; set; }
+        protected internal FieldIdentifier FieldIdentifier { get; set; }
 
         /// <summary>
         /// Gets or sets the current value of the input.
@@ -142,7 +142,7 @@ protected InputBase()
         /// </summary>
         /// <param name="value">The value to format.</param>
         /// <returns>A string representation of the value.</returns>
-        protected virtual string? FormatValueAsString(TValue value)
+        protected virtual string? FormatValueAsString([AllowNull] TValue value)
             => value?.ToString();
 
         /// <summary>

src/Components/Web/src/Forms/InputDate.cs

@@ -34,7 +34,7 @@ protected override void BuildRenderTree(RenderTreeBuilder builder)
         }
 
         /// <inheritdoc />
-        protected override string FormatValueAsString(TValue value)
+        protected override string FormatValueAsString([AllowNull] TValue value)
         {
             switch (value)
             {

src/Components/Web/src/Forms/InputExtensions.cs

@@ -0,0 +1,35 @@
+// 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.
+
+using System;
+using System.Diagnostics.CodeAnalysis;
+using System.Globalization;
+
+namespace Microsoft.AspNetCore.Components.Forms
+{
+    internal static class InputExtensions
+    {
+        public static bool TryParseSelectableValueFromString<TValue>(this InputBase<TValue> input, string? value, [MaybeNull] out TValue result, [NotNullWhen(false)] out string? validationErrorMessage)
+        {
+            try
+            {
+                if (BindConverter.TryConvertTo<TValue>(value, CultureInfo.CurrentCulture, out var parsedValue))
+                {
+                    result = parsedValue;
+                    validationErrorMessage = null;
+                    return true;
+                }
+                else
+                {
+                    result = default;
+                    validationErrorMessage = $"The {input.FieldIdentifier.FieldName} field is not valid.";
+                    return false;
+                }
+            }
+            catch (InvalidOperationException ex)
+            {
+                throw new InvalidOperationException($"{input.GetType()} does not support the type '{typeof(TValue)}'.", ex);
+            }
+        }
+    }
+}

src/Components/Web/src/Forms/InputNumber.cs

@@ -74,7 +74,7 @@ protected override bool TryParseValueFromString(string? value, [MaybeNull] out T
         /// </summary>
         /// <param name="value">The value to format.</param>
         /// <returns>A string representation of the value.</returns>
-        protected override string? FormatValueAsString(TValue value)
+        protected override string? FormatValueAsString([AllowNull] TValue value)
         {
             // Avoiding a cast to IFormattable to avoid boxing.
             switch (value)

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

@@ -0,0 +1,82 @@
+// 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.
+
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
+using Microsoft.AspNetCore.Components.Rendering;
+
+namespace Microsoft.AspNetCore.Components.Forms
+{
+    /// <summary>
+    /// An input component used for selecting a value from a group of choices.
+    /// </summary>
+    public class InputRadio<TValue> : ComponentBase
+    {
+        /// <summary>
+        /// Gets context for this <see cref="InputRadio{TValue}"/>.
+        /// </summary>
+        internal InputRadioContext? Context { get; private set; }
+
+        /// <summary>
+        /// 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 Value { get; set; } = default;
+
+        /// <summary>
+        /// Gets or sets the name of the parent input radio group.
+        /// </summary>
+        [Parameter] public string? Name { get; set; }
+
+        [CascadingParameter] private InputRadioContext? CascadedContext { get; set; }
+
+        private string GetCssClass(string fieldClass)
+        {
+            if (AdditionalAttributes != null &&
+                AdditionalAttributes.TryGetValue("class", out var @class) &&
+                !string.IsNullOrEmpty(Convert.ToString(@class)))
+            {
+                return $"{@class} {fieldClass}";
+            }
+
+            return fieldClass;
+        }
+
+        /// <inheritdoc />
+        protected override void OnParametersSet()
+        {
+            Context = string.IsNullOrEmpty(Name) ? CascadedContext : CascadedContext?.FindContextInAncestors(Name);
+
+            if (Context == null)
+            {
+                throw new InvalidOperationException($"{GetType()} must have an ancestor {typeof(InputRadioGroup<TValue>)} " +
+                    $"with a matching 'Name' property, if specified.");
+            }
+        }
+
+        /// <inheritdoc />
+        protected override void BuildRenderTree(RenderTreeBuilder builder)
+        {
+            Debug.Assert(Context != null);
+
+            builder.OpenElement(0, "input");
+            builder.AddMultipleAttributes(1, AdditionalAttributes);
+            builder.AddAttribute(2, "class", GetCssClass(Context.FieldClass));
+            builder.AddAttribute(3, "type", "radio");
+            builder.AddAttribute(4, "name", Context.GroupName);
+            builder.AddAttribute(5, "value", BindConverter.FormatValue(Value?.ToString()));
+            builder.AddAttribute(6, "checked", Context.CurrentValue?.Equals(Value));
+            builder.AddAttribute(7, "onchange", Context.ChangeEventCallback);
+            builder.CloseElement();
+        }
+    }
+}

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

@@ -0,0 +1,64 @@
+// 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>
+    internal 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 a css class indicating the validation state of input radio elements.
+        /// </summary>
+        public string FieldClass { 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="fieldClass">The css class indicating the validation state of input radio elements.</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,
+            string fieldClass,
+            EventCallback<ChangeEventArgs> changeEventCallback)
+        {
+            _parentContext = parentContext;
+
+            GroupName = groupName;
+            CurrentValue = currentValue;
+            FieldClass = fieldClass;
+            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);
+    }
+}