Adding custom property attributes in Entity Framework code

Question

Is there any way to add custom attributes to properties in EF generated code? The only thing I can see as a plausible solution would be to come up with a custom T4 template. However, because of the nature of the attribute it would be impossible to determine the correct attribute parameter per EF property.

Answer 1

You can do this by specifying a metadata type that mirrors the properties and is used simply for attribution.

[MetadataType(typeof(Dinner_Validation))] 
public partial class Dinner 
{} 

public class Dinner_Validation 
{ 
    [Required] 
    public string Title { get; set; } 
}

Steve Smith blogs about it here.

Unfortunately the above approach is brittle to refactoring. Another option is to use the new POCO entities. These avoid compile-time code generation altogether as far as I can tell. I haven't used them yet so can't comment on any pitfalls or tradeoffs.