Question

we are developing MVC3 application such that most of our action methods are called via ajax calls and return partialviews. we come across a situation where we need to identify if the action method is called from Form Authentication time out.

public ActionResult LogOn()
{ 
 // I want to return View("LogOn"); if the call is coming from 
 // Form Authentication time out                       
    return PartialView(Model);
}

here is my web.config looks like:

<authentication mode="Forms">
  <forms loginUrl="~/Home/LogOn" timeout="20" />
</authentication>

Appreciate your input.

Answer 1

Your action will never be hit if the authentication cookie has timed out. The forms authentication module directly redirects to the logon page. One possibility for you to detect this happening from client scripting is to set a custom HTTP header in the controller action serving this logon page:

public ActionResult LogOn()
{
    var model = ...
    Response.AppendHeader("X-LOGON", "true");
    return View(model);
} 

and then when performing your AJAX request you could use the getResponseHeader method on the XHR object in order to verify if the X-LOGON header was set meaning that the server redirected to the logon page. In this case in your success AJAX handler instead of simply injecting the server response into the DOM or relying on the returned JSON you could show some alert message informing the user that his authentication session has timed out and he needs to login again. Another possibility is to automatically redirect him to the logon page using the window.location.href method:

$.ajax({
    url: '/home/some_protected_action',
    success: function (data, textStatus, XMLHttpRequest) {
        if (XMLHttpRequest.getResponseHeader('X-LOGON') === 'true') {
            // the LogOn page was displayed as a result of this request 
            // probably timeout => act accordingly
        }
    }
});