DataAnnotations 中的自定义验证器属性异常

Question

以前有人见过这个异常吗？ Google 或 Bing 的结果绝对很少。

IsValid(object value) has not been implemented by this class.  
The preferred entry point is GetValidationResult() and classes should override 
IsValid(object value, ValidationContext context).

这是自定义验证器：

public class PriceAttribute : ValidationAttribute
    {
        public string Id { get; set; }

        protected override ValidationResult IsValid(object value, ValidationContext validationContext)
        {
            //I think this definition for IsValid is in DataAnnotations 4.0
            return base.IsValid(value, validationContext);
        }

        public override bool IsValid(object value)
        {
            //This I think is the older definition. Not sure why it expects this
            return base.IsValid(value);
        }

    }

谢谢！

Answer 1

您实际上应该为这些方法之一提供实现，而不是调用 base.IsValid(value) 或 base.IsValid(value,validationContext)。

public class PriceAttribute : ValidationAttribute
{
    public string Id { get; set; }

    public override bool IsValid(object value)
    {
        return Id == "120"; // <-- put your condition here
    }
}

如果可以在不检查上下文的其他值的情况下验证该值，则只需重写 IsValid(object value) 即可。