Adding DataAnnontations to Generated Partial Classes

Question

I have a Subsonic3 Active Record generated partial User class which I've extended on with some methods in a separate partial class.

I would like to know if it is possible to add Data Annotations to the member properties on one partial class where it's declared on the other Subsonic Generated one I tried this.

public partial class User
{
    [DataType(DataType.EmailAddress, ErrorMessage = "Please enter an email address")]
    public string Email { get; set; }

    ...
}

That examples gives the "Member is already defined" error.

I think I might have seen an example a while ago of what I'm trying to do with Dynamic Data and Linq2Sql.

Answer 1

What you will need to do is create a 'buddy class' and apply the Data Annotations to that class:

[MetadataType(typeof(UserValidation))]
public partial class User 
{
  ...
}

public class UserValidation
{
  [DataType(DataType.EmailAddress, ErrorMessage = "Please enter an email address")]
  public string Email { get; set; }
}

Answer 2

You should create a buddy class as explained here by Scott Guthrie http://weblogs.asp.net/scottgu/archive/2010/01/15/asp-net-mvc-2-model-validation.aspx