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>
@@ -97,7 +97,29 @@ 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 : Microsoft.AspNetCore.Components.ComponentBase
+    {
+        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() { }
+    }
+    public partial class InputRadio<TValue> : Microsoft.AspNetCore.Components.Forms.InputBase<TValue>
+    {
+        public InputRadio() { }
+        protected string? GroupName { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } }
+        [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 { } }
+        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

@@ -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 +96,26 @@ 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 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() { }
+    }
+    public partial class InputRadio<TValue> : Microsoft.AspNetCore.Components.Forms.InputBase<TValue>
+    {
+        public InputRadio() { }
+        protected string? GroupName { [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 { } }
+        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>
     {
         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 +1,40 @@
+// 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)
+        {
+            if (typeof(TValue) == typeof(string))
+            {
+                result = (TValue)(object?)value;
+                validationErrorMessage = null;
+                return true;
+            }
+            else if (typeof(TValue).IsEnum || (Nullable.GetUnderlyingType(typeof(TValue))?.IsEnum ?? false))
+            {
+                var success = BindConverter.TryConvertTo<TValue>(value, CultureInfo.CurrentCulture, out var parsedValue);
+                if (success)
+                {
+                    result = parsedValue;
+                    validationErrorMessage = null;
+                    return true;
+                }
+                else
+                {
+                    result = default;
+                    validationErrorMessage = $"The {input.FieldIdentifier.FieldName} field is not valid.";
+                    return false;
+                }
+            }
+
+            throw new InvalidOperationException($"{input.GetType()} does not support the type '{typeof(TValue)}'.");
+        }
+    }
+}

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 +1,68 @@
+// 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;
+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> : InputBase<TValue>
+    {
+        /// <summary>
+        /// Gets the name of this <see cref="InputRadio{TValue}"/> group.
+        /// </summary>
+        protected string? GroupName { get; private set; }
+
+        /// <summary>
+        /// Gets or sets the value that will be bound when this radio input is selected.
+        /// </summary>
+        [AllowNull]
+        [MaybeNull]
+        [Parameter]
+        public TValue SelectedValue { get; set; } = default;
+
+        /// <summary>
+        /// Gets or sets group name inherited from an ancestor <see cref="InputRadioGroup"/>.
+        /// </summary>
+        [CascadingParameter] InputRadioGroup? CascadedRadioGroup { get; set; }
+
+        /// <inheritdoc />
+        protected override void OnParametersSet()
+        {
+            GroupName = AdditionalAttributes != null && AdditionalAttributes.TryGetValue("name", out var nameAttribute) ?
+                nameAttribute as string :
+                CascadedRadioGroup?.GroupName;
+
+            if (string.IsNullOrEmpty(GroupName))
+            {
+                throw new InvalidOperationException($"{GetType()} requires either an explicit string attribute 'name' or " +
+                    $"an ancestor {nameof(InputRadioGroup)}.");
+            }
+        }
+
+        /// <inheritdoc />
+        protected override void BuildRenderTree(RenderTreeBuilder builder)
+        {
+            Debug.Assert(GroupName != 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.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/InputRadioGroup.cs

@@ -0,0 +1,47 @@
+// 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;
+using Microsoft.AspNetCore.Components.Rendering;
+
+namespace Microsoft.AspNetCore.Components.Forms
+{
+    /// <summary>
+    /// Groups child <see cref="InputRadio{TValue}"/> components.
+    /// </summary>
+    public class InputRadioGroup : ComponentBase
+    {
+        private readonly string _defaultGroupName = Guid.NewGuid().ToString("N");
+
+        internal string? GroupName { get; private set; }
+
+        /// <summary>
+        /// Gets or sets the child content to be rendering inside the <see cref="InputRadioGroup"/>.
+        /// </summary>
+        [Parameter] public RenderFragment? ChildContent { get; set; }
+
+        /// <summary>
+        /// Gets or sets the name of the group.
+        /// </summary>
+        [Parameter] public string? Name { get; set; }
+
+        /// <inheritdoc />
+        protected override void OnParametersSet()
+        {
+            GroupName = !string.IsNullOrEmpty(Name) ? Name : _defaultGroupName;
+        }
+
+        /// <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);
+            builder.CloseComponent();
+        }
+    }
+}

src/Components/Web/src/Forms/InputSelect.cs

@@ -1,9 +1,7 @@
 // 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;
 using Microsoft.AspNetCore.Components.Rendering;
 
 namespace Microsoft.AspNetCore.Components.Forms
@@ -13,8 +11,6 @@ namespace Microsoft.AspNetCore.Components.Forms
     /// </summary>
     public class InputSelect<TValue> : InputBase<TValue>
     {
-        private static readonly Type? _nullableUnderlyingType = Nullable.GetUnderlyingType(typeof(TValue));
-
         /// <summary>
         /// Gets or sets the child content to be rendering inside the select element.
         /// </summary>
@@ -34,31 +30,6 @@ protected override void BuildRenderTree(RenderTreeBuilder builder)
 
         /// <inheritdoc />
         protected override bool TryParseValueFromString(string? value, [MaybeNull] out TValue result, [NotNullWhen(false)] out string? validationErrorMessage)
-        {
-            if (typeof(TValue) == typeof(string))
-            {
-                result = (TValue)(object?)value;
-                validationErrorMessage = null;
-                return true;
-            }
-            else if (typeof(TValue).IsEnum || (_nullableUnderlyingType != null && _nullableUnderlyingType.IsEnum))
-            {
-                var success = BindConverter.TryConvertTo<TValue>(value, CultureInfo.CurrentCulture, out var parsedValue);
-                if (success)
-                {
-                    result = parsedValue;
-                    validationErrorMessage = null;
-                    return true;
-                }
-                else
-                {
-                    result = default;
-                    validationErrorMessage = $"The {FieldIdentifier.FieldName} field is not valid.";
-                    return false;
-                }
-            }
-
-            throw new InvalidOperationException($"{GetType()} does not support the type '{typeof(TValue)}'.");
-        }
+            => this.TryParseSelectableValueFromString(value, out result, out validationErrorMessage);
     }
 }