Making custom dataannotation attributes work with MVC client side validation

In a previous blog entry I showed you a easier approach to localized DataAnnotation attributes.

The problem with that approach was that client side validation didn’t work. It isn’t hard to fix. All you need is to borrow some code from the built in DataAnnotation support and reference the custom attributes instead.

Here is a sample implementation.

    public class RequiredAttributeAdapter : DataAnnotationsModelValidator<RequiredAttribute>
    {
        public RequiredAttributeAdapter(ModelMetadata metadata, ControllerContext context, RequiredAttribute attribute)
            : base(metadata, context, attribute)
        {
        }

        public static void SelfRegister()
        {
            DataAnnotationsModelValidatorProvider
                .RegisterAdapter(
                    typeof (RequiredAttribute),
                    typeof (RequiredAttributeAdapter));
        }

        public override IEnumerable<ModelClientValidationRule> GetClientValidationRules()
        {
            return new[] { new ModelClientValidationRequiredRule(ErrorMessage) };
        }
    }

Then simply call RequiredAttributeAdapter.SelfRegister(); somewhere in your Global.asax