Why HttpContext.Current.Session is null in Global.asax?

Question

I'm using VS2010 and created a simple asp. web forms application, using Development Server to test it.
I try to store user data - queried from sql server - in the session, since I don't want to access database in every request. I'm using the 'Application_AuthenticateRequest' and the 'Session_Start' methods.
First round: AuthenticateRequest called. The following code ran:

public static void Initialize(string login_name, bool force_refresh)
    {
      HttpSessionState Session = HttpContext.Current.Session;
      object o = Session == null ? null : Session["EMPLOYEE_DATA"];
      if (force_refresh || o == null || o.GetType() != typeof(Employee) || (o as Employee).login_name!= login_name)
      {
        _current = UIManager.GetEmployee(login_name);
        if (Session != null)
        {
          Session["EMPLOYEE_DATA"] = _current;
        }
      }
      else
      {
        _current = (Employee)o;
      }
    }

The _current variable is a private static field published through a static property. In the first round the Session is null, and I think it's ok because the Session_Start not called yet. The Session_Start looks like this:

protected void Session_Start(object sender, EventArgs e)
{
  Session["EMPLOYEE_DATA"] = EmployeeFactory.Current;
}

In the next round the Session_Start is not called of course but in the AuthenticateRequest I can't access to the session. The HttpContext.Current.Session is null and the this.Session reference throw a HttpException says the "Session state is not available in this context".

However I can access the Session from any of the page_load events but it's a bad practice I think that I put authentication every page_load. Any idea how can I access to the Session?

Thanks for advice,
Péter

score 38 · Accepted Answer · answered Nov 15 '10 at 15:39

38

You're not able to use Session on the Application_AuthenticateRequest becauase it's not bound at that moment.

I think you're able to use the event Application_AcquireRequestState.

answered Nov 15 '10 at 15:39

Torbjörn Hansson

18,354
5
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42

Thank You. It was the solution. – Péter Nov 15 '10 at 16:05
2

@Torbjörn Hansson: Sometimes it's null, do you have any idea why that? – Homam Jul 17 '11 at 19:35
Wish I could upvote this a thousand times! That simple change just ended hours of suffering. – Matt Cashatt Mar 20 '13 at 17:20
4

I think it's necessary to apply this test: if (System.Web.HttpContext.Current.Session != null) because the Application_AcquireRequestState can be called more then once and the session can be null in some case. This is how it works for me, I have from here: http://stackoverflow.com/questions/9897112/global-asax-event-that-has-access-to-session-state – Daniel Katz Dec 13 '13 at 22:34

score -2 · Answer 2 · edited Mar 12 '13 at 07:16

-2

try to use the below code in page_Load

Response.AppendHeader("Refresh", Convert.ToString(Session.Timeout * 15) + "; 
URL=SessionExpPage.aspx");

edited Mar 12 '13 at 07:16

Vishal Suthar

17,013
3
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105

answered Nov 30 '12 at 06:43

Mahesh

129
2
2
15

Why HttpContext.Current.Session is null in Global.asax?

2 Answers2

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