Archive for November, 2008

Some time ago, I read an article on how to detect a session timeout in a ASP.Net Web forms application by placing some code in a Base Page. The code worked for me and you could read more about it here.  In my last post I mentioned that Microsoft released a beta version of their MVC implementation of ASP.Net and since them, I have been playing around with it. But, as with Web forms, I still needed a way to detect a session timeout and perform an action when a timeout is detected. So, I decided to use the same code implemented in the original article and implement it into my MVC project. I decided to write a custom action filter and apply it to my controller actions where I need to ensure that my session was still active. Here is the code for my action filter.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using System.Reflection;

namespace Web {

    public class SessionExpireFilterAttribute : ActionFilterAttribute {

        public override void OnActionExecuting( ActionExecutingContext filterContext ) {
            HttpContext ctx = HttpContext.Current;

            // check if session is supported
            if ( ctx.Session != null ) {

                // check if a new session id was generated
                if ( ctx.Session.IsNewSession ) {

                    // If it says it is a new session, but an existing cookie exists, then it must
                    // have timed out
                    string sessionCookie = ctx.Request.Headers[ "Cookie" ];
                    if ( ( null != sessionCookie ) && ( sessionCookie.IndexOf ( "ASP.NET_SessionId" ) >= 0 ) ) {

                        ctx.Response.Redirect ( "~/Home/Login" );
                    }
                }
            }

            base.OnActionExecuting ( filterContext );
        }
    }
}

And then, I would apply this filter to my Controller action methods like so:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using System.Web.Mvc.Ajax;

namespace Web.Controllers {

    public class HomeController : Controller {

        [SessionExpireFilter]
        public ActionResult Index( ) {
            // This method will not execute if our session has expired

            // render Home Page
            return View();
        }

        public ActionResult Login() {
            // render Login page
            return View();
        }
    }
}

The code is pretty straightforward. I just apply the [SessionExpireFilter] attribute on each method where I want to ensure that our session is still valid. If you have any questions, leave a comment under this post. Until next time…

Happy Coding!