如何通过Dependency Property绑定用户控件的ValueRange最大最小值至DataGrid？

问题根源分析 #

你的代码存在三个核心错误，导致始终获取Int32RangeChecker的默认值：

1. MyUserControl属性逻辑错误：MinRange的getter返回的是maxRange，构造函数赋值顺序完全颠倒
2. XAML绑定目标类型错误：RelativeSource指定的MyForm并非你的用户控件类型，应该是MyUserControl
3. 嵌套DependencyObject绑定限制：ValidationRule不是DependencyObject，嵌套绑定Int32RangeChecker的属性无法正确传递值

修正后的完整代码 #

1. 修复MyUserControl的属性与构造函数 #

public partial class MyUserControl : UserControl, INotifyPropertyChanged
{
    private int minRange;
    private int maxRange;

    public int MaxRange
    {
        get => maxRange;
        set
        {
            maxRange = value;
            OnPropertyChanged();
        }
    }

    public int MinRange
    {
        get => minRange; // 修正：返回正确的私有字段
        set
        {
            minRange = value; // 修正：赋值给正确的私有字段
            OnPropertyChanged();
        }
    }

    public MyUserControl(int minRange = 0, int maxRange = 500)
    {
        InitializeComponent();
        // 修正赋值顺序
        MinRange = minRange;
        MaxRange = maxRange;
    }

    public event PropertyChangedEventHandler PropertyChanged;
    protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

2. 简化验证规则，避免嵌套绑定问题 #

直接在ValueRangeRule中暴露Min/Max属性，跳过Int32RangeChecker的嵌套绑定：

public class ValueRangeRule : ValidationRule
{
    public int Minimum { get; set; }
    public int Maximum { get; set; }

    public override ValidationResult Validate(object value, CultureInfo cultureInfo)
    {
        double myValue = 0;

        try
        {
            if (!string.IsNullOrEmpty(value?.ToString()))
                myValue = double.Parse(value.ToString());
        }
        catch (Exception e)
        {
            return new ValidationResult(false, $"非法字符或 {e.Message}");
        }

        if (myValue <= Minimum || myValue >= Maximum)
        {
            return new ValidationResult(false, $"请输入 {Minimum}-{Maximum} 范围内的值。");
        }
        return ValidationResult.ValidResult;
    }
}

3. 修正XAML绑定目标 #

<TextBox.Text>
    <Binding Path="MyValue" Converter="{StaticResource ConvertString}" Mode="TwoWay" UpdateSourceTrigger="PropertyChanged">
        <Binding.ValidationRules>
            <local:ValueRangeRule
                Minimum="{Binding MinRange, RelativeSource={RelativeSource AncestorType={x:Type local:MyUserControl}}}"
                Maximum="{Binding MaxRange, RelativeSource={RelativeSource AncestorType={x:Type local:MyUserControl}}}" />
        </Binding.ValidationRules>
    </Binding>
</TextBox.Text>

额外注意事项 #

• 确保用户控件的DataContext未被意外覆盖，否则RelativeSource绑定会失效
• 如果需要动态更新Min/Max值，MyUserControl的属性已正确触发PropertyChanged事件，验证规则会在绑定源更新时自动重新验证
• 若需实时响应范围值变化并重新验证，可手动调用TextBox.GetBindingExpression(TextBox.TextProperty).UpdateSource()

内容的提问来源于stack exchange，提问作者abdou_dev