Entity Framework causes circular references?

I have a problem with EF Code First and it complains about a circular reference in the generated proxies. Maybe we have a convention conflict that causes EF to create a circular reference on the fly? The dataset produces no errors when simply passed directly to the JSON serializer.

/* Assume all dependencies and namespaces are referenced and used */

///the base object
public class A {
    [Key]
    public int AId { set; get; }

    //the tree
    public B MyB { set; get; }
}

//the tree nodes
public class B {
    [Key]
    public int BId { set; get; }
    public int AId { set; get; }
    public int ParendId { set; get; }
    public virtual ICollection<B> Children { set; get; }
}

///the context
public class ABContext : DbContext {
    public DbSet<A> As { set; get; }
    public DbSet<B> Bs { set; get; }
}

///later in a controller...
[HttpGet]
public JsonResult Get(string sid)
{
    int id = int.Parse(sid);
    using (ABContext abc = new ABContext()) {
        A a = abc.As.Where(i=>开发者_如何学Ci.AId==id).Single();
        return Json(a, JsonRequestBehavior.AllowGet);
    }
}

Thoughts and comments are all very welcome!

Thank you, Alexander Brevig

I had the same problem.

http://garfbradazweb.wordpress.com/2011/09/22/mvc-3-entity-framework-and-serializing-jsoncircular-references/

A bit of googling, and it seems the JavaScriptSerializer has gets it knickers in a twist trying to traverse your Entity Framework objects which have relationships.