Question

OK so to set and read variables from the current session

String Myvar =(string) System.Web.HttpContext.Current.Session[“MyVariable”]

To set

System.Web.HttpContext.Current.Session[“MyVariable”] = “NewValue”

I can do neither, I get a System.NullReferenceException: Object reference not set to an instance of an object. from System.Web.HttpContext.Current.Session.

In my web.config I have

<sessionState mode="StateServer" stateConnectionString="tcpip=127.0.0.1:42424" cookieless="false" timeout="20">
</sessionState>  

I have read a dozen articles on the the necessity of IHttpHandler and an IRequiresSessionState interface. I think the issue may be caused because I am requesting this information in Page_PreInit. I found a solution in a stack overflow article but I don’t seem be using it properly to actually make this go.

I am not sure what I am missing. Thanks in advance.

Answer 1

To access the session state pre-init you can do something like this. I use it so that I can have a different admin master than the regular user one. Each page has a method at the top.

PageTools tools = new PageTools();
protected void Page_PreInit(object sender, EventArgs e)
{
    tools.setMasterPage(Page, Context);
}

PageTools is my class that holds the method that chooses the appropriate mater page and has the http handler.

public void setMasterPage(Page page, HttpContext context)
    /***********************************************************************
     * Author   Daniel Tweddell
     * Date     9/18/09
     * 
     * Several of the pages are for non-admin use, however these pages will
     * also be used by the admin users and will need to have the admin menu
     * and such.  So based on the login, we either show the page with the
     * standard master or if the user is admin, use the admin master.
     ***********************************************************************/
    {
        if (context.Handler is IReadOnlySessionState || context.Handler is IRequiresSessionState)
        {
            context.Handler = Handler();
        }
        String sMasterPage="~/content/page.master";
        if (userinfo.IsUserAdmin) sMasterPage="~/content/administrator/admin.master";//make sure the user is admin
        page.MasterPageFile = sMasterPage; 
    }

Here is a step by step to setting up the httphandler. (which is the other thing you’ll need.