Question

The title is somewhat self explanatory. I have an entity that has another key already defined (that must remain that way) and I need to validate that a certain field is unique.

I am hoping to use a Validator applied in the metadata. But I can’t use DomainService there since the code must run on both Server and Client. So I have no idea how I could access my entity set to see if the field’s value is unique….

Ideas?

Thanks!

Answer 1

The way to do this is to create a file with the extension .shared.cs on the Server side. Put the validator in that:

public class CustomValidation
{
     public static ValidationResult ValidateUnique(object o, ValidationContext c)
     {
         #if SILVERLIGHT
             //Do actual validation client-side:
             MyObject mo = c.ObjectInstance as mo; //Object we are checking is type MyObject
             MyDS ctx = new MyDS; //Domain Service
             System.ServiceModel.DomainServices.Client.InvokeOperation<bool> 
                    isUnique = //some invoke operation in Domain Service;

             isUnique .Completed += (s, e) =>
             {
                 if (!isUnique .HasError && !isUnique.Value)
                 {
                      //return error;
                      mo.ValidationErrors.Add(error);
                 }
             };
         #endif
         //Server-side always returns success:
         return ValidationResult.Success;
     }
}