Circular Reference exception with JSON Serialisation with MVC3 and EF4 CTP5w

Question

I\'m having problems with a circular reference when i try and serialise an object returned via EF4 CTP5. Im using the code first approach and simple poco\'s for my model.

Answer 1

I used the following ContractResolver. Note that I inherited from the CamelCaseContractPropertyResolver to get that feature as well, but you can also inherit directly from DefaultContractResolver.

using System;
using System.Collections.Generic;
using System.Reflection;
using Newtonsoft.Json.Serialization;

namespace MyNamespace
{
    /// 

    /// This class enables EntityFramework POCO objects to be serialized. In some cases POCO
    /// objects are subclassed by a proxy which has an additional member _entityWrapper. This
    /// object prevents serialization (circular references and references to non-serializable types).
    /// This removes the _entityWrapper from the list of members to be serialized.
    /// 
    public class ContractResolver : CamelCasePropertyNamesContractResolver
    {
        protected override List GetSerializableMembers(Type objectType)
        {
            if (objectType.FullName.StartsWith("System.Data.Entity.DynamicProxies."))
            {
                var members = base.GetSerializableMembers(objectType);
                members.RemoveAll(memberInfo => memberInfo.Name == "_entityWrapper");
                return members;
            }
            return base.GetSerializableMembers(objectType);
        }
    }
}

To use it, create your serializer and then set the ContractResolver property to a new instance of this class:

var ser = JsonSerializer.Create(sJsonSerializerSettings);            
ser.ContractResolver = new ContractResolver();