How do you use DataAnnotations in WCF

[Sevententh]

Hi I've been struggling with this all week, validation on EDM in a WCF service (using basicHttpBinding). Ideally I'd like to use DataAnnotations as it seems easier/quicker to code when I have 100+ tables that all require some validation on the fields. The following code works using On<FieldName>Changing but I can't get the same to work with DataAnnotations.

public partial class tblCfg\_Agent
{
    partial void OnAgentCodeChanging(string value)
    {
        if (value == String.Empty)
        {
            throw new ValidationException("Agent must have a code");
        }
        if (value.Length > 5)
        {
            throw new ValidationException("Agent Code must be no more than 5 characters");
        }
    }
}

But if I want to use the following no validation happens

\[MetadataType(typeof(tblCfg\_AgentValidation))\]
public partial class tblCfg\_Agent
{}
public class tblCfg\_AgentValidation
{
    \[Required(ErrorMessage = "Agent must have a code")\] 
    \[StringLength(5, ErrorMessage = "Agent Code must be no more than 5 characters")\] 
    public string AgentCode { get; set; } 
}

Could somebody spot what I'm doing wrong please :sigh: Update code

    /// <summary>
    /// Updates an existing tblCfg\_Agent
    /// </summary>
    public void Update(tblCfg\_Agent ds)
    {
        try
        {
            EntitiesContext context = new EntitiesContext();

            context.AttachUpdated(ds);
            context.SaveChanges();
        }
        catch (OptimisticConcurrencyException e)
        {
            // someone else changed the data, throw
            throw (e);
        }
    }