title: Localizing DataAnnotations Custom Validation Attribute
body: <p>I'm currently working in an MVC 2 app which has to have everything localized in n-languages (currently 2, none of them english btw). I validate my model classes with DataAnnotations but when I wanted to validate a DateTime field found out that the DataTypeAttribute returns always true, no matter it was a valid date or not (that's because when I enter a random string "foo", the IsValid() method checks against "01/01/0001 ", dont know why).</p>
  
  <p>Decided to write my own validator extending ValidationAtribute class:</p>
  
  <pre><code>public class DateTimeAttribute : ValidationAttribute
  {
      public override bool IsValid(object value)
      {
          DateTime result;
          if (value.ToString().Equals("01/01/0001 0:00:00"))
          {
                  return false;
          }
          return DateTime.TryParse(value.ToString(), out result);
      }
  }
  </code></pre>
  
  <p>Now it checks OK when is valid and when it's not, but my problem starts when I try to localize it:</p>
  
  <pre><code>[Required(ErrorMessageResourceType = typeof(MSG), ErrorMessageResourceName = "INS_DATA_Required")]
  [CustomValidation.DateTime(ErrorMessageResourceType = typeof(MSG), ErrorMessageResourceName = "INS_DATA_DataType")]
  public DateTime INS_DATA { get; set; }
  </code></pre>
  
  <p>If I put nothing in the field I get a localized MSG (MSG being my resource class) for the key=INS_DATA_Required but if I put a bad-formatted date I get the "The value 'foo' is not valid for INS_DATA" default message and not the localized MSG.</p>
  
  <p>What am I misssing?</p>