编辑“︁C Sharp 属性验证”︁（章节）

== 高级验证技术 ==

=== 自定义验证特性 ===
创建继承自ValidationAttribute的类实现复杂规则：

<syntaxhighlight lang="csharp">
public class EvenNumberAttribute : ValidationAttribute
{
    protected override ValidationResult IsValid(object value, ValidationContext context)
    {
        if (value is int number && number % 2 == 0)
            return ValidationResult.Success;
            
        return new ValidationResult("必须输入偶数");
    }
}

public class InventoryItem
{
    [EvenNumber]
    public int ShelfQuantity { get; set; }
}
</syntaxhighlight>

=== 跨属性验证 ===
通过类级别特性实现多属性关联验证：

<syntaxhighlight lang="csharp">
[AttributeUsage(AttributeTargets.Class)]
public class DateRangeValidAttribute : ValidationAttribute
{
    public override bool IsValid(object value)
    {
        var model = value as Event;
        return model.StartDate < model.EndDate;
    }
}

[DateRangeValid(ErrorMessage = "结束日期必须晚于开始日期")]
public class Event
{
    public DateTime StartDate { get; set; }
    public DateTime EndDate { get; set; }
}
</syntaxhighlight>