401 response code for json requests with ASP.NET MVC

Question

How to disable standard ASP.NET handling of 401 response code (redirecting to login page) for AJAX/JSON requests?

For web-pages it's okay, but for AJAX I need to get right 401 error code instead of good looking 302/200 for login page.

Update: There are several solutions from Phil Haack, PM of ASP.NET MVC - http://haacked.com/archive/2011/10/04/prevent-forms-authentication-login-page-redirect-when-you-donrsquot-want.aspx

Answer 1

In classic ASP.NET you get a 401 http response code when calling a WebMethod with Ajax. I hope they'll change it in future versions of ASP.NET MVC. Right now I'm using this hack:

protected void Application_EndRequest()
{
    if (Context.Response.StatusCode == 302 && Context.Request.Headers["X-Requested-With"] == "XMLHttpRequest")
    {
        Context.Response.Clear();
        Context.Response.StatusCode = 401;
    }
}