Can I access session state from an HTTPModule?

Question

I could really do with updating a user's session variables from within my HTTPModule, but from what I can see, it isn't possible.

UPDATE: My code is currently running inside the OnBeginRequest () event handler.

UPDATE: Following advice received so far, I tried adding this to the Init () routine in my HTTPModule:

AddHandler context.PreRequestHandlerExecute, AddressOf OnPreRequestHandlerExecute

But in my OnPreRequestHandlerExecute routine, the session state is still unavailable!

Thanks, and apologies if I'm missing something!

Answer 1

Found this over on the ASP.NET forums:

using System; using System.Web; using System.Web.Security; using System.Web.SessionState; using System.Diagnostics;  // This code demonstrates how to make session state available in HttpModule, // regardless of requested resource. // author: Tomasz Jastrzebski  public class MyHttpModule : IHttpModule {    public void Init(HttpApplication application)    {       application.PostAcquireRequestState += new EventHandler(Application_PostAcquireRequestState);       application.PostMapRequestHandler += new EventHandler(Application_PostMapRequestHandler);    }     void Application_PostMapRequestHandler(object source, EventArgs e)    {       HttpApplication app = (HttpApplication)source;        if (app.Context.Handler is IReadOnlySessionState || app.Context.Handler is IRequiresSessionState) {          // no need to replace the current handler          return;       }        // swap the current handler       app.Context.Handler = new MyHttpHandler(app.Context.Handler);    }     void Application_PostAcquireRequestState(object source, EventArgs e)    {       HttpApplication app = (HttpApplication)source;        MyHttpHandler resourceHttpHandler = HttpContext.Current.Handler as MyHttpHandler;        if (resourceHttpHandler != null) {          // set the original handler back          HttpContext.Current.Handler = resourceHttpHandler.OriginalHandler;       }        // -> at this point session state should be available        Debug.Assert(app.Session != null, "it did not work :(");    }     public void Dispose()    {     }     // a temp handler used to force the SessionStateModule to load session state    public class MyHttpHandler : IHttpHandler, IRequiresSessionState    {       internal readonly IHttpHandler OriginalHandler;        public MyHttpHandler(IHttpHandler originalHandler)       {          OriginalHandler = originalHandler;       }        public void ProcessRequest(HttpContext context)       {          // do not worry, ProcessRequest() will not be called, but let's be safe          throw new InvalidOperationException("MyHttpHandler cannot process requests.");       }        public bool IsReusable       {          // IsReusable must be set to false since class has a member!          get { return false; }       }    } } 

Answer 2

HttpContext.Current.Session should Just Work, assuming your HTTP Module isn't handling any pipeline events that occur prior to the session state being initialized...

EDIT, after clarification in comments: when handling the BeginRequest event, the Session object will indeed still be null/Nothing, as it hasn't been initialized by the ASP.NET runtime yet. To work around this, move your handling code to an event that occurs after PostAcquireRequestState -- I like PreRequestHandlerExecute for that myself, as all low-level work is pretty much done at this stage, but you still pre-empt any normal processing.