Cannot bind JSON to ASP.NET Model in multi part post - asp.net-mvc

Question

I am using ASP.NET MVC3 controller to receive multi-part form post from WP7 app. The format of the post is something as follows:
{User Agent stuff}
Content-Type: multipart/form-data; boundary=8cdb3c15d07d36a
--8cdb3c15d07d36a
Content-Disposition: form-data; name="user"
Content-Type: application/json
{"UserName":"ashish","Password":"ashish"}
--8cdb3c15d07d36a--
And my controller looks like:
public class User
{
public string UserName { get; set;}
public string Password { get; set; }
}
[HttpPost]
public JsonResult CreateFeed(User user)
{
}
What I am seeing is that User is not bound to json and user object is always null. I tried making user string and manually bound it to User class using DataContractJsonSerializer and it does create and assign an object but I am baffled as to why it does not work.
I tried using non-multi-form post and found it works with the same json. Any help would be appreciated.
I saw these posts: ASP.NET MVC. How to create Action method that accepts and multipart/form-data and HTTP spec http://www.w3.org/TR/html401/interact/forms.html#h-17.13.4.2 while coming up with my code.

Answer 1

The answer you're looking for is here
You have to read it in as a string and parse that internally.
So your action would look like this:
[HttpPost]
public JsonResult CreateFeed(string jsonResponse)
{
JavaScriptSerializer jsonSerializer = new JavaScriptSerializer();
User user = jsonSerializer.Deserialize<User>(jsonResponse);
}
Or if you don't have nice helpful Content-Disposition with names to associate with the controller action methods you can do something like the below:
[HttpPost]
public JsonResult CreateFeed()
{
StreamReader reader = new StreamReader(Request.InputStream);
string jsonResponse = reader.ReadToEnd();
JavaScriptSerializer jsonSerializer = new JavaScriptSerializer();
User user = jsonSerializer.Deserialize<User>(jsonResponse);
}
This approach is further outlined here