asp.net mvc DataAnnotation Validation

Question

Hi, i going to create some validation for custom object in my app. But i have some trouble when try to create CustomValidation rule. My object has field - BirthDay - which not required but if user enter it i need to validate it on simple validation, for example user DataType validation - DataType.DateTime. When i am try to do it i have validation error - BirthDay is required. When i create custom validation and always return true i have same error. Below some lines of code:

[MetadataType(typeof(User.Metadata))]
public class User
{
 #region Metadata  
 private class Metadata
 {
  [Required(ErrorMessage="Name is required")]
  [StringLength(5, ErrorMessage="Max Length is 5")]
  public string Name { get; set; }
  [CustomValidation(typeof(User), "ValidateBirthDay", ErrorMessage="We have trouble.")]
  public DateTime BirthDay { get; set; }

 }
 #endregion

 public static bool ValidateBirthDay(object value)
 {   
  return true;
 }

 public int? ID { get; set; }
 public string Name { get; set; }  
 public DateTime BirthDay { get; set; }
}

p.s. sorry for my English =)

Answer 1

You need to make your propery nullable, ie

public DateTime? BirthDay { get; set; }

so it can have a null value and not required to be set.

Also the way you use the CustomValidation attribute doesn't seem right. I believe you need to create a class that derives from ValidationAttribute base class and pass its type in CustomValidation attribute's first param.