InputTime component with form support

src/Components/Web/src/Forms/InputTime.cs

@@ -0,0 +1,112 @@
+using System;
+using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
+using System.Globalization;
+using Microsoft.AspNetCore.Components.Rendering;
+
+namespace Microsoft.AspNetCore.Components.Forms
+{
+    /// <summary>
+    /// An input component for editing time values.
+    /// Supported types are <see cref="DateTime"/> and <see cref="DateTimeOffset"/>.
+    /// </summary>
+    public class InputTime<TValue> : InputBase<TValue>
+    {
+        private const string TimeFormat = "HH:mm:ss"; // Compatible with HTML time inputs
+
+        /// <summary>
+        /// Gets or sets the error message used when displaying an a parsing error.
+        /// </summary>
+        [Parameter] public string ParsingErrorMessage { get; set; } = "The {0} field must be a time.";
+
+        /// <inheritdoc />
+        protected override void BuildRenderTree(RenderTreeBuilder builder)
+        {
+            builder.OpenElement(0, "input");
+            builder.AddMultipleAttributes(1, AdditionalAttributes);
+            builder.AddAttribute(2, "type", "time");
+            builder.AddAttribute(3, "class", CssClass);
+            builder.AddAttribute(4, "value", BindConverter.FormatValue(CurrentValueAsString));
+            builder.AddAttribute(5, "onchange", EventCallback.Factory.CreateBinder<string?>(this, __value => CurrentValueAsString = __value, CurrentValueAsString));
+            builder.CloseElement();
+        }
+
+        /// <inheritdoc />
+        protected override string FormatValueAsString(TValue? value)
+        {
+            switch (value)
+            {
+                case DateTime dateTimeValue:
+                    return BindConverter.FormatValue(dateTimeValue, TimeFormat, CultureInfo.InvariantCulture);
+                case DateTimeOffset dateTimeOffsetValue:
+                    return BindConverter.FormatValue(dateTimeOffsetValue, TimeFormat, CultureInfo.InvariantCulture);
+                default:
+                    return string.Empty; // Handles null for Nullable<DateTime>, etc.
+            }
+        }
+
+        /// <inheritdoc />
+        protected override bool TryParseValueFromString(string? value, [MaybeNullWhen(false)] out TValue result, [NotNullWhen(false)] out string? validationErrorMessage)
+        {
+            // Unwrap nullable types. We don't have to deal with receiving empty values for nullable
+            // types here, because the underlying InputBase already covers that.
+            var targetType = Nullable.GetUnderlyingType(typeof(TValue)) ?? typeof(TValue);
+
+            bool success;
+            if (targetType == typeof(DateTime))
+            {
+                success = TryParseDateTime(value, out result);
+            }
+            else if (targetType == typeof(DateTimeOffset))
+            {
+                success = TryParseDateTimeOffset(value, out result);
+            }
+            else
+            {
+                throw new InvalidOperationException($"The type '{targetType}' is not a supported time type.");
+            }
+
+            if (success)
+            {
+                Debug.Assert(result != null);
+                validationErrorMessage = null;
+                return true;
+            }
+            else
+            {
+                validationErrorMessage = string.Format(ParsingErrorMessage, DisplayName ?? FieldIdentifier.FieldName);
+                return false;
+            }
+        }
+
+        private static bool TryParseDateTime(string? value, [MaybeNullWhen(false)] out TValue result)
+        {
+            var success = BindConverter.TryConvertToDateTime(value, CultureInfo.InvariantCulture, TimeFormat, out var parsedValue);
+            if (success)
+            {
+                result = (TValue)(object)parsedValue;
+                return true;
+            }
+            else
+            {
+                result = default;
+                return false;
+            }
+        }
+
+        private static bool TryParseDateTimeOffset(string? value, [MaybeNullWhen(false)] out TValue result)
+        {
+            var success = BindConverter.TryConvertToDateTimeOffset(value, CultureInfo.InvariantCulture, TimeFormat, out var parsedValue);
+            if (success)
+            {
+                result = (TValue)(object)parsedValue;
+                return true;
+            }
+            else
+            {
+                result = default;
+                return false;
+            }
+        }
+    }
+}