MetadataType problem

Question

I\'m using VS2008 SP1, WCF Ria Service July 2009 CTP. I found out that MetadataType does not work in partial class mode, really don\'t know what I have missed out:

W

Answer 1

Many thanks to Jeremy Gruenwald for the answer above... I was completely stuck on this one.

I wanted to create a standard validation class based on this solution, but I didn't want to have to pass in the metadata class type because it just felt ugly.

To achieve this I created a static class which does a lookup on the custom attributes to get the metadata class type and then registers that class before returning the validation results.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;
using System.Linq;

namespace MyApp.Validation
{
    public static class EntityValidator
    {
        public static List Validate(object instance, bool validateAllProperties = true)
        {
            RegisterMetadataClass(instance);

            var validationContext = new ValidationContext(instance, null, null);
            var validationResults = new List();

            Validator.TryValidateObject(instance, validationContext, validationResults, validateAllProperties);

            return validationResults;
        }

        private static void RegisterMetadataClass(object instance)
        {
            var modelType = instance.GetType();
            var metadataType = GetMetadataType(modelType);

            if (metadataType != null) 
            {
                TypeDescriptor.AddProviderTransparent(new AssociatedMetadataTypeTypeDescriptionProvider(modelType, metadataType), modelType);
            }
        }

        private static Type GetMetadataType(Type type)
        {
            var attribute = (MetadataTypeAttribute)type.GetCustomAttributes(typeof (MetadataTypeAttribute), true).FirstOrDefault();
            return attribute == null ? null : attribute.MetadataClassType;
        }
    }
}

usage is a simple as:

var errors = EntityValidator.Validate(myEntity);