Question

I have some common code that runs at the beginning of multiple controller actions. I would like to refactor that code into a static class to promote reuse of that code block.

The code checks for a variable, looks for a cookie and if a condition is met, the code should redirect to another page (controller/action).

The problem is that everything works properly (including the cookie lookup) but the Redirect does not fire. The code passes over the redirect and the redirect never happens.

What is the proper way to redirect in a helper class?

Here is the code now:

This line is not working: myController.HttpContext.Response.Redirect(redirectURL);

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

namespace MyProject.WebUI
{
    public static class SessionValidationHelper
    {
        // helper class to encapsulate common routines to check for missing session data
        public static void SessionIdRequired(string id, Controller myController)
        {
            if (id == null || id == "")
            {
                // check cookie
                if (myController.ControllerContext.HttpContext.Request.Cookies.AllKeys.Contains("cookiename"))
                {
                    // if a session cookie was found, send to the registration recovery page
                    string sessionGuidCookieValue = "";
                    sessionGuidCookieValue = myController.ControllerContext.HttpContext.Request.Cookies["cookiename"].Value;

                    // check if GUID/SessionID exists in persistent cache

                    // send to Session Recovery
                    //myController.HttpContext.Response.RedirectToRoute("SessionRecovery", new { Controller = "SessionRecovery", Action = "Index", id = sessionGuidCookieValue });
                    string redirectURL = @"~/SessionRecovery/Index/" + sessionGuidCookieValue;

                    // this code isn't working
                    myController.HttpContext.Response.Redirect(redirectURL);
                }
            }
        }
    }
}

Answer 1

You can create an attribute that is a filter and decorate the action with it:
(I have placed the code you provided in the attribute)

public class SessionValidationAttribute : FilterAttribute, IAuthorizationFilter
{
    public void OnAuthorization(AuthorizationContext filterContext)
    {
       if (filterContext.Result == null)
       {
          var id = filterContext.RouteData.Values["id"] as string;
          if (id == null || id == "")
          {
            // check cookie
            if (filterContext.Controller.ControllerContext
               .HttpContext.Request.Cookies.AllKeys
               .Contains("cookiename"))
            {
                // if a session cookie was found,
                // send to the registration recovery page
                string sessionGuidCookieValue = "";
                sessionGuidCookieValue = filterContext.Controller
                    .ControllerContext.HttpContext.Request
                    .Cookies["cookiename"].Value;

                // check if GUID/SessionID exists in persistent cache

                // send to Session Recovery
                string redirectURL = @"~/SessionRecovery/Index/"
                        + sessionGuidCookieValue;

                // this code isn't working
                filterContext.Result = new RedirectResult(redirectURL);
            }
          }
       }
    }

    public abstract bool CanAccessResource(User user);
}

And on your action you do this:

[SessionValidationAttribute]
public ActionResult MyAction()
{
     // code of the action
}

Or if you want to apply it to all actions inside a class:

[SessionValidationAttribute]
public class MyController : Controller
{
     // code of the class, containing all actions
}

Or if you want to apply this GLOBALLY (be carefull with this):
In your Application class (the one inheriting System.Web.HttpApplication, you can do this:

public class MvcApplication : System.Web.HttpApplication
{
    protected void Application_Start()
    {
        GlobalFilters.Filters.Add(new SessionValidationAttribute());

        // register routes
    }
}