asp.net mvc keep object alive, information
[HttpPost]
public ActionResult Index(LoginModel loginModel)
{
    if (ModelState.IsValid)
    {
       // some lines of code . bla bla bla
       TempData["loginModel"] = loginModel;
       return RedirectToAction("index", "premium");
     }
     ...
}

public ActionResult Index()
{
   var loginModel = TempData["loginModel"] as LoginModel;
   ...
}

Object reference not set to an instance of an object.

Description: An unhandled exception occurred during the execution of the current web     request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error:


Line 22:
Line 23:             var loginModel = TempData["loginModel"] as LoginModel;
Line 24:             string username = loginModel.username;
Line 25:             string password = loginModel.password;
Line 26:             premiumModel.username = username;