簡單的方式

Question

我有我的DomainRegistry模型以下屬性：

[Domain("Extension")] 
    public string Name { get; set; } 

    [Required(ErrorMessage = "Select extension")] 
    public string Extension { get; set; } 

域名是我的自定義數據註解，我已經在我的IsValid方法來訪問值tryed一切內部擴展屬性。

我有我的自定義數據註解如下：

[AttributeUsage(AttributeTargets.Field | AttributeTargets.Property, AllowMultiple = false, Inherited = true)] 
public class DomainAttribute : ValidationAttribute 
{ 
    public string ExtensionProperty { get; set; } 

    public DominioAttribute(string property) 
    { 
     ExtensionProperty = property; 
    } 

    protected override ValidationResult IsValid(object value, ValidationContext validationContext) 
    { 
     PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(value); 
     var extension = (string) properties.Find(Propriedade, true).GetValue(value); 
     if (extension == null) return new ValidationResult("Extension shouldn't be null"); 
     return null; 
    } 

我似乎無法進去IsValid方法從擴展中的值。任何人有任何提示如何做到這一點？另外我需要將擴展​​名作爲字符串值。

Answer 1

試試這個：

protected override ValidationResult IsValid(object value, ValidationContext validationContext) 
    { 
     var containerType = validationContext.ObjectInstance.GetType(); 
     var field = containerType.GetProperty("Extension"); 

     if (field != null) 
     { 
      var extensionValue = field.GetValue(validationContext.ObjectInstance, null); 

      return extensionValue != null ? ValidationResult.Success : new ValidationResult("Extension shouldn't be null", new[] { validationContext.MemberName }); 
     } 

     return ValidationResult.Success; 
    } 

Answer 2

IsValid方法的value參數包含註釋屬性的實際值，所以在您的情況下Name屬性的值。訪問實際DomainRegistry實例（獲得Extension屬性的值），你應該使用validationContext.ObjectInstance屬性：

protected override ValidationResult IsValid(object value, ValidationContext validationContext) 
{ 
    PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(validationContext.ObjectInstance); 
    var extension = (string)properties.Find(ExtensionProperty, true).GetValue(validationContext.ObjectInstance); 
    if (extension == null) return new ValidationResult("Extension shouldn't be null"); 
    return ValidationResult.Success; 
}