.NET MVC Route to specific area controller based on a session variable

Question

Lets say I am using MVC for my web application and I have an area that contains multiple controllers... MyController1, MyController2 and MyController3

These controllers are used by users in certain groups: UserGroup1, UserGroup2 and UserGroup3. I will store the group id in the session.

I would like the client requests to look generic like this: www.mysite.com/MyArea/MyController/SomeAction

So, how do I assign the respective controller based on the group id variable stored in session?

some pseudo code:

var id = HttpContext.Current.Session["GroupId"];
if id == 1
  use MyController1
else if id == 2 
  use MyController2
else if id == 3
  use MyController3

I know I could hit a controller and perform a redirect, but is there somewhere higher up in the stack that I can have more control over the controller assignment.

Answer 1

After reading an article on MSDN https://msdn.microsoft.com/en-us/library/cc668201(v=vs.110).aspx I came up with the following solution:

1. Implement a custom MvcHandler that will handle the logic of choosing a controller
2. Implement an IRouteHandler
3. Attach the IRouteHandler to the route that is registered in the AreaRegistration

---

public class MyRouteHandler : IRouteHandler
{
        IHttpHandler IRouteHandler.GetHttpHandler(RequestContext requestContext)
        {
                return new MyMvcHandler(requestContext);
        }
}

---

public class MyMvcHandler : MvcHandler, IHttpHandler
{
        public MyMvcHandler(RequestContext requestContext) : base(requestContext)
        {
        }

        private string GetControllerName(HttpContextBase httpContext)
        {
                string controllerName = this.RequestContext.RouteData.GetRequiredString("controller");
                var groupId = httpContext.Session["GroupId"] as string;
                if (!String.IsNullOrEmpty(groupId) && !String.IsNullOrEmpty(controllerName))
                {
                    controllerName = groupId + controllerName;
                }
                return controllerName;
        }

        protected override IAsyncResult BeginProcessRequest(HttpContextBase httpContext, AsyncCallback callback, object state)
        {
                RequestContext.RouteData.Values["controller"] = this.GetControllerName(httpContext);
                return base.BeginProcessRequest(httpContext, callback, state);
        }
}

---

and finally, register the RouteHandler:

    public override void RegisterArea(AreaRegistrationContext context)
    {
        context.MapRoute(
            "default",
            "{controller}/{action}/{id}",
            new { action = "Index", id = UrlParameter.Optional }
        ).RouteHandler = new MyRouteHandler();            
    }