Keeping data between sessions without using get, post or cookies - asp.net-mvc

Question

I have one controller class with two action functions. One action is my login page with one view, and the other is my backend page with multiple views.
public ActionResult Login(...)
{
if (logged in or login success)
{
return RedirectToAction("Backend","Controller");
}
...
return View();
}
public ActionResult Backend(...)
{
if(session expired or not logged in)
{
return RedirectToAction("Login","Controller");
}
...
return View("someView");
}
The issue is when the backend action has to send the user to the login action and I want to show the user a message like "Session expired" on the login page.
As an example ViewBag only lives in the current session. But is there a similar and easy way to store information between sessions? So I can set a message in the backend, then redirect to login, and have the login read that message and display it in the view? Kinda like PersistentViewBag.
I really do not want to use get, post or cookies, as is a viable option but then I rather just have the login as its own view in the backend action instead.

Answer 1

You can simply use the querystring for passing data when you are redirecting to the login page.
public ActionResult Backend(...)
{
if(session expired or not logged in)
{
return RedirectToAction("Login","Controller",new { IsSessionExpired = true });
}
...
return View("someView");
}
In your Login action you can check the querystring and decide if you want to display the message.
Update
You can also use TempData if you do not want to use the querystring.
public ActionResult Backend(...)
{
if(session expired or not logged in)
{
TempData["IsSessionExpired"] = true;
return RedirectToAction("Login","Controller");
}
...
return View("someView");
}
Then you can check it in Login action:
if(TempData["IsSessionExpired"] != null)
{
//Show message
}