Serialize Entity Framework Object using Json.Net

I had this problem and solved it by adding the Newtonsoft.Json.JsonIgnoreAttribute to the property causing the loop. Obviously, that property won't be serialized. To help with this problem, I typically will have both the foreign reference ID and the foreign class in my entities. I realize this is not intuitive (or super great OO), but it is the way recommended by Julia Lerman in her book Programming Entity Framework: Code First. I've found it helps smooth out several problems with Entity Framework.

 public class SomeEntity
 {
      [JsonIgnore]
      public ForeignEntity SomeForeignEntity {get;set;}
      public Guid ForeignEntityId {get;set;}
 }

Update: I forgot to mention I also needed to disable proxies on the DbContext like so:

dataContext.Configuration.ProxyCreationEnabled = false;

If you are writing the code for a service (which seems likely if you are serializing), then this is probably not a problem, but there are some things you lose when the proxy creation is disabled. See here: http://www.sellsbrothers.com/posts/Details/12665 for more details.

I am using the MS Web Api, so I just disable the the proxy creation when I construct my controller:

public class MailingApiController : ApiController
{
    public MailingApiController()
    {
        PreventDeepSerialization();
    }

    private static void PreventDeepSerialization()
    {
        var dataContext = Injector.Get<IIntertwyneDbContext>();
        dataContext.Configuration.ProxyCreationEnabled = false;
    }
      ....

To get around this I converted my Entities to POCO based Code First. To do this right click inside your edmx window and select:

Add code generation item > Code tab > EF POCO Entity Generator.

Note that you might need to install it with nuget if you don't see it.

At runtime however EF adds proxy classes to those objects for tracking purposes but they tend to mess up with the serialization process. To prevent this we can simply set ProxyCreationEnabled to false as follows:

var context = new YourEntities();
context.Configuration.ProxyCreationEnabled = false;

var results = context.YourEntity.Take(100).ToList();

You can then safely return JSON.NET serialized data by omitting the default reference looping as follows:

return JsonConvert.SerializeObject(results, Formatting.Indented, 
    new jsonSerializerSettings { 
        ReferenceLoopHandling = ReferenceLoopHandling.Ignore 
    });