Better way of doing strongly-typed ASP.NET MVC sessions

Question

I am developing an ASP.NET MVC project and want to use strongly-typed session objects. I have implemented the following Controller-derived class to expose this object:

public class StrongController<_T> : Controller
    where _T : new()
{
    public _T SessionObject
    {
        get
        {
            if (Session[typeof(_T).FullName] == null)
            {
                _T newsession = new _T();
                Session[typeof(_T).FullName] = newsession;
                return newsession;
            }
            else
                return (_T)Session[typeof(_T).FullName];
        }
    }

}

This allows me to define a session object for each controller, which is in line with the concept of controller isolation. Is there a better/more "correct" way, perhaps something that is officially supported by Microsoft?

Answer 1

This way other objects won't have access to this object (e.g. ActionFilter). I do it like this:

public interface IUserDataStorage<T>
{
   T Access { get; set; }
}

public class HttpUserDataStorage<T>: IUserDataStorage<T>
  where T : class
{
  public T Access
  {
     get { return HttpContext.Current.Session[typeof(T).FullName] as T; }
     set { HttpContext.Current.Session[typeof(T).FullName] = value; }
  }
}

Then, I can either inject IUserDataStorage into controller's constructor, or use ServiceLocator.Current.GetInstance(typeof(IUserDataStorage<T>)) inside ActionFilter.

public class MyController: Controller
{
   // automatically passed by IoC container
   public MyController(IUserDataStorage<MyObject> objectData)
   {
   }
}

Of course for cases when all controllers need this (e.g. ICurrentUser) you may want to use property injection instead.

Answer 2

This might be better for what you want. I would just create an extension method that can access your session. The added benefit to the extension method is that you no longer have to inherit from a controller, or have to inject a dependency that really isn't necessary to begin with.

public static class SessionExtensions {
  public static T Get<T>(this HttpSessionBase session, string key)  {
     var result;
     if (session.TryGetValue(key, out result))
     {
        return (T)result;
     }
     // or throw an exception, whatever you want.
     return default(T);
   }
 }


public class HomeController : Controller {
    public ActionResult Index() {
       //....

       var candy = Session.Get<Candy>("chocolate");

       return View(); 
    }

}