Create Typed Session State in ASP.NET

Having a strongly-typed object or interface to develop against is generally much easier than dealing with loosely-typed interfaces. Many common errors can be caught at compile time rather than at run time, which hastens development time.

One of the things that has bothered me about the Session object in ASP.NET is that it is loosely typed, returning everything as the Object base type. Equally bothersome, the Session object requires you to pass in a string key to obtain the object you want. I don’t know how many times I’ve forgotten what key I was using for a piece of data and had to look through my code to find it. Maintaining a data dictionary in a separate document helped, but I would sometimes start using a new piece of data and forget to update my dictionary!

After having an application developed where I had the Session object sprinkled throughout my code I realized that I could create an object to wrap the Session object and clean up my code. It looks something like this:

public class State {
	public static int CustomerId{
		get{ return (int)HttpContext.Current.Session["CustomerId"]; }
		set{ HttpContext.Current.Session["CustomerId"] = value; }
	}
}

Now code that once appeared as:

DataTable tbl = GetInvoices((int)Session["CustomerId"]);

now looks like this:

DataTable tbl = GetInvoices(State.CustomerId);

It takes a little bit of work to setup each session variable but once you try it I think you’ll find your code is a whole lot cleaner and bug free.