Check Session object so that user does not skip steps in a form

Question

I have a form with multiple steps. When the user finishes the first step, a session is created.

On every step, except the first one, I am using the following check to determine whether a session has been created:

if(Session["form_data"] == null)
{
     throw new ArgumentException("Session not created!");
}

This works fine if the user has not started filling in a form. However, the user can navigate to, say, step 5 if he filled in step 1. This is due to the fact that a session is created in step 1 and therefore my check would fail.

How can I get around this? How can I ensure that the user does not skip form steps by typing in the URL directly in the address bar once he filled in step 1?

Answer 1

You can assign some value to Session and increment it on each step instead of just checking that if session exists.

if(Session["form_data"] == null && Session["form_data"].ToString() == "2") //2 is for second step
{
     throw new ArgumentException("Session not created!");
}

For first step

Session["form_data"] = "1";

For second step

Session["form_data"] = "2";

So on...

Answer 2

You could store another value in the session to indicate which "step" you are on.

if(Session["Step"].ToString() != "1")
{
     throw new ArgumentException("Step is not correct");
}

Answer 3

You could create an session array. initialize it with null values. each index can be each form stage. once a stage is complete assign that index a true value. on load of each form you can check if any of the previous indexes are null eg if the user on form 3 then check if form 2 or 1 is null.