Q:

Model Binder of Json. Net not being used when i post an object

To clarify...
I configure my WebApiConfig like so:
config. Formatters. JsonFormatter. SerializerSettings. Binder = new TypeNameSerializationBinder("namespace.{0}, assembly");
config. Formatters. JsonFormatter. SerializerSettings. TypeNameHandling = TypeNameHandling. Auto;

This should allow me to bind derived classes to base class. 
And binder does work when WebApi serializes objects to JSON, and sends them to client, but when I post them back to server, the binder isn't used (BindToType method never gets called), and my objects get bound to base class. 
When i serialize/deserialize objects manually with this settings it all works fine. 
Any ideas? 

A:

After some research, I found that this is a bug in ASP.NET Web Api.  When the url encoded parameters are parsed, it just creates a new JsonSerializer (without passing global settings). 
I filed it here
http://aspnetwebstack.codeplex.com/workitem/609

