feat(DateTimePicker): use DateTimeHelper enhance IsEditable function

src/BootstrapBlazor/Components/DateTimePicker/DateTimePicker.razor.cs

@@ -4,7 +4,6 @@
 // Maintainer: Argo Zhang(argo@live.ca) Website: https://www.blazor.zone
 
 using Microsoft.Extensions.Localization;
-using System.Globalization;
 
 namespace BootstrapBlazor.Components;
 
@@ -569,10 +568,9 @@ private async Task OnClear()
     /// <param name="validationErrorMessage"></param>
     protected override bool TryParseValueFromString(string value, [MaybeNullWhen(false)] out TValue result, out string? validationErrorMessage)
     {
-        var format = ViewMode == DatePickerViewMode.DateTime ? DateTimeFormat : DateFormat;
         result = default;
         validationErrorMessage = null;
-        var ret = DateTime.TryParseExact(value, format, CultureInfo.InvariantCulture, DateTimeStyles.None, out var val);
+        var ret = DateTimeHelper.TryToDateTime(value, out var val);
         if (ret)
         {
             result = (TValue)(object)val;

src/BootstrapBlazor/Utils/DateTimeHelper.cs

@@ -0,0 +1,87 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the Apache 2.0 License
+// See the LICENSE file in the project root for more information.
+// Maintainer: Argo Zhang(argo@live.ca) Website: https://www.blazor.zone
+
+using System.Globalization;
+
+namespace BootstrapBlazor.Components;
+
+static class DateTimeHelper
+{
+    /// <summary>
+    /// 无分隔符等标准解析无法识别的紧凑格式，需要显式列出
+    /// </summary>
+    private static readonly string[] CompactFormats =
+    [
+        "yyyyMMdd",
+        "yyyyMMddHHmm",
+        "yyyyMMddHHmmss",
+        "yyyyMMddHHmmssfff",
+        "yyyyMMdd HHmmss",
+        "yyyyMMdd HH:mm:ss",
+        "yyyyMMdd HH:mm",
+        "yyyy-M-d",
+        "yyyy/M/d"
+    ];
+
+    /// <summary>
+    /// 将字符串解析为 <see cref="DateTime"/>，无法解析时返回 <see langword="null"/>
+    /// </summary>
+    public static DateTime? ToDateTime(string value)
+        => TryToDateTime(value, out var result) ? result : null;
+
+    /// <summary>
+    /// 将字符串解析为 <see cref="DateTime"/>，无法解析时返回 <paramref name="defaultValue"/>
+    /// </summary>
+    /// <param name="value">要解析的字符串</param>
+    /// <param name="defaultValue">解析失败时返回的默认值</param>
+    public static DateTime ToDateTime(string value, DateTime defaultValue)
+            => TryToDateTime(value, out var result) ? result : defaultValue;
+
+    /// <summary>
+    /// 尝试将字符串解析为 <see cref="DateTime"/>
+    /// </summary>
+    /// <param name="value">要解析的字符串</param>
+    /// <param name="result">解析成功时的结果，失败时为 <see cref="DateTime.MinValue"/></param>
+    public static bool TryToDateTime(string value, out DateTime result)
+    {
+        result = DateTime.MinValue;
+        if (string.IsNullOrWhiteSpace(value))
+        {
+            return false;
+        }
+
+        var text = value.Trim();
+
+        // 先尝试无分隔符等紧凑格式（如 20260501），这类格式标准解析无法识别
+        if (DateTime.TryParseExact(text, CompactFormats, CultureInfo.InvariantCulture, DateTimeStyles.None, out result))
+        {
+            return true;
+        }
+
+        // 再回退到通用解析，覆盖 2026-5-1、2026/5/1、2026-05-01 13:04:05 等带分隔符写法
+        return DateTime.TryParse(text, CultureInfo.InvariantCulture, DateTimeStyles.AllowWhiteSpaces, out result);
+    }
+
+    /// <summary>
+    /// 将字符串解析为 <see cref="DateTimeOffset"/>，无法解析时返回 <see langword="null"/>
+    /// </summary>
+    /// <remarks>
+    /// 适用于 <c>DateTimePicker</c> 绑定 <see cref="DateTimeOffset"/> 的场景；
+    /// 不含时区信息时按本地时区处理。
+    /// </remarks>
+    /// <param name="value">要解析的字符串</param>
+    /// <returns>解析成功返回对应的 <see cref="DateTimeOffset"/>，否则返回 <see langword="null"/></returns>
+    public static DateTimeOffset? ToDateTimeOffset(string value)
+    {
+        if (TryToDateTime(value, out var dateTime))
+        {
+            // 紧凑/无时区字符串解析出的 Kind 为 Unspecified，按本地时区补齐偏移
+            return dateTime.Kind == DateTimeKind.Unspecified
+                ? new DateTimeOffset(DateTime.SpecifyKind(dateTime, DateTimeKind.Local))
+                : new DateTimeOffset(dateTime);
+        }
+        return null;
+    }
+}

test/UnitTest/Utils/DateTimeHelperTest.cs

@@ -0,0 +1,148 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the Apache 2.0 License
+// See the LICENSE file in the project root for more information.
+// Maintainer: Argo Zhang(argo@live.ca) Website: https://www.blazor.zone
+
+using System.Runtime.CompilerServices;
+
+namespace UnitTest.Utils;
+
+/// <summary>
+/// <c>DateTimeHelper</c> 为内部类，通过 <see cref="UnsafeAccessorAttribute"/> 配合
+/// <see cref="UnsafeAccessorTypeAttribute"/> 直接访问其静态方法进行测试
+/// </summary>
+public class DateTimeHelperTest
+{
+    /// <summary>
+    /// 内部类型的程序集限定名
+    /// </summary>
+    private const string HelperTypeName = "BootstrapBlazor.Components.DateTimeHelper, BootstrapBlazor";
+
+    [Fact]
+    public void ToDateTime_Ok()
+    {
+        // 紧凑格式解析成功
+        Assert.Equal(new DateTime(2026, 5, 1), ToDateTime(null, "20260501"));
+
+        // 带分隔符格式解析成功
+        Assert.Equal(new DateTime(2026, 5, 1, 13, 4, 5), ToDateTime(null, "2026-05-01 13:04:05"));
+    }
+
+    [Fact]
+    public void ToDateTime_Null()
+    {
+        // 解析失败返回 null
+        Assert.Null(ToDateTime(null, "test"));
+        Assert.Null(ToDateTime(null, null!));
+    }
+
+    [Fact]
+    public void ToDateTime_DefaultValue_Ok()
+    {
+        var defaultValue = new DateTime(2020, 1, 1);
+
+        // 解析成功返回解析值
+        Assert.Equal(new DateTime(2026, 5, 1), ToDateTimeWithDefaultValue(null, "20260501", defaultValue));
+
+        // 解析失败返回默认值
+        Assert.Equal(defaultValue, ToDateTimeWithDefaultValue(null, "test", defaultValue));
+    }
+
+    [Theory]
+    [InlineData(null)]
+    [InlineData("")]
+    [InlineData(" ")]
+    [InlineData("\t")]
+    public void TryToDateTime_NullOrWhiteSpace(string? value)
+    {
+        // 空字符串直接返回 false 且结果为 DateTime.MinValue
+        Assert.False(TryToDateTime(null, value!, out var result));
+        Assert.Equal(DateTime.MinValue, result);
+    }
+
+    [Fact]
+    public void TryToDateTime_Invalid()
+    {
+        // 两种解析方式均失败
+        Assert.False(TryToDateTime(null, "test", out var result));
+        Assert.Equal(DateTime.MinValue, result);
+
+        Assert.False(TryToDateTime(null, "20261301", out _));
+    }
+
+    [Theory]
+    [InlineData("20260501", 2026, 5, 1, 0, 0, 0, 0)]
+    [InlineData("202605011304", 2026, 5, 1, 13, 4, 0, 0)]
+    [InlineData("20260501130405", 2026, 5, 1, 13, 4, 5, 0)]
+    [InlineData("20260501130405123", 2026, 5, 1, 13, 4, 5, 123)]
+    [InlineData("20260501 130405", 2026, 5, 1, 13, 4, 5, 0)]
+    [InlineData("20260501 13:04:05", 2026, 5, 1, 13, 4, 5, 0)]
+    [InlineData("20260501 13:04", 2026, 5, 1, 13, 4, 0, 0)]
+    [InlineData("2026-5-1", 2026, 5, 1, 0, 0, 0, 0)]
+    [InlineData("2026/5/1", 2026, 5, 1, 0, 0, 0, 0)]
+    public void TryToDateTime_CompactFormats(string value, int year, int month, int day, int hour, int minute, int second, int millisecond)
+    {
+        // 紧凑格式由 TryParseExact 分支解析
+        Assert.True(TryToDateTime(null, value, out var result));
+        Assert.Equal(new DateTime(year, month, day, hour, minute, second, millisecond), result);
+    }
+
+    [Theory]
+    [InlineData("2026-05-01")]
+    [InlineData("2026/05/01")]
+    public void TryToDateTime_Fallback(string value)
+    {
+        // 标准格式由 TryParse 回退分支解析
+        Assert.True(TryToDateTime(null, value, out var result));
+        Assert.Equal(new DateTime(2026, 5, 1), result);
+    }
+
+    [Fact]
+    public void TryToDateTime_Trim()
+    {
+        // 前后空白被裁剪后可正常解析
+        Assert.True(TryToDateTime(null, "  20260501  ", out var result));
+        Assert.Equal(new DateTime(2026, 5, 1), result);
+    }
+
+    [Fact]
+    public void ToDateTimeOffset_Unspecified()
+    {
+        // 无时区信息按本地时区补齐偏移
+        var value = new DateTime(2026, 5, 1, 13, 4, 5);
+        var expected = TimeZoneInfo.Local.GetUtcOffset(value);
+
+        var actual = ToDateTimeOffset(null, "20260501 130405");
+        Assert.NotNull(actual);
+        Assert.Equal(expected, actual.Value.Offset);
+        Assert.Equal(value, actual.Value.DateTime);
+    }
+
+    [Fact]
+    public void ToDateTimeOffset_Local()
+    {
+        // 带时区信息的字符串解析出的 Kind 不是 Unspecified，直接构造
+        var actual = ToDateTimeOffset(null, "2026-05-01T13:04:05Z");
+        Assert.NotNull(actual);
+        Assert.Equal(new DateTime(2026, 5, 1, 13, 4, 5, DateTimeKind.Utc), actual.Value.UtcDateTime);
+    }
+
+    [Fact]
+    public void ToDateTimeOffset_Null()
+    {
+        // 解析失败返回 null
+        Assert.Null(ToDateTimeOffset(null, "test"));
+    }
+
+    [UnsafeAccessor(UnsafeAccessorKind.StaticMethod, Name = "ToDateTime")]
+    static extern DateTime? ToDateTime([UnsafeAccessorType(HelperTypeName)] object? @this, string value);
+
+    [UnsafeAccessor(UnsafeAccessorKind.StaticMethod, Name = "ToDateTime")]
+    static extern DateTime ToDateTimeWithDefaultValue([UnsafeAccessorType(HelperTypeName)] object? @this, string value, DateTime defaultValue);
+
+    [UnsafeAccessor(UnsafeAccessorKind.StaticMethod, Name = "TryToDateTime")]
+    static extern bool TryToDateTime([UnsafeAccessorType(HelperTypeName)] object? @this, string value, out DateTime result);
+
+    [UnsafeAccessor(UnsafeAccessorKind.StaticMethod, Name = "ToDateTimeOffset")]
+    static extern DateTimeOffset? ToDateTimeOffset([UnsafeAccessorType(HelperTypeName)] object? @this, string value);
+}