DataAnnotations中的自定義驗證器屬性異常

Question

有沒有人看到過此異常？ Google或Bing的結果絕對非常少。

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). 

這裏的自定義驗證：

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); 
     } 

    } 

謝謝！

Answer 1

實際上，您應該爲其中一種方法提供實現，而不是調用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 
    } 
} 

如果該值可以不檢查上下文的其他值進行驗證，你可以重寫IsValid(object value)。