Why is HttpContext.Current.Server.MapPath invalid in a asynchronous function? RSS

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  mycwcgr

  Participant

  1646 Points

  924 Posts

  Why is HttpContext.Current.Server.MapPath invalid in a asynchronous function?

  Jul 08, 2007 10:54 PM|LINK

  After run the Part A and click the button1,  I get the error

  Object reference not set to an instance of an object.

  
  I think the error is caused by the function HttpContext.Current.Server.MapPath

  Is it seems hat HttpContext.Current  can't use in asynchronous function?

  How can I get a  server physical path in a asynchronous function?  Many Thanks!

  
  =============================Part A=======================
  using System;
  using System.Data;
  using System.Configuration;
  using System.Web;
  using System.Web.Security;
  using System.Web.UI;
  using System.Web.UI.WebControls;
  using System.Web.UI.WebControls.WebParts;
  using System.Web.UI.HtmlControls;

  public partial class _Default : System.Web.UI.Page
  {
      protected void Page_Load(object sender, EventArgs e)
      {

      }
      protected void Button1_Click(object sender, EventArgs e)
      {
          AsynCatchEmailToDB();
      }

  
      private delegate void CatchEmailCallBack();

  
      public static void AsynCatchEmailToDB()
      {

          CatchEmailCallBack myCatchEmailCallBack = new CatchEmailCallBack(Sync);
          myCatchEmailCallBack.BeginInvoke(null, null);
      }

      private static void Sync()
      {
          string path = HttpContext.Current.Server.MapPath(@"~/Temp");
      }
  }

  =============================Part A=======================
  

  HostMath - A online LaTeX formula editor and math equation editor
  • Moved by limno on Jul 08, 2007 11:11 PM
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  REA_ANDREW

  Member

  472 Points

  119 Posts

  Re: Why is HttpContext.Current.Server.MapPath invalid in a asynchronous function?

  Jul 08, 2007 11:15 PM|LINK

  try removing static from both methods. 

   

      public void AsynCatchEmailToDB()
      {

          CatchEmailCallBack myCatchEmailCallBack = new CatchEmailCallBack(Sync);
          myCatchEmailCallBack.BeginInvoke(null, null);
      }

      private  void Sync()
      {
          string path = HttpContext.Current.Server.MapPath(@"~/Temp");
      }

  Cheers,
  
  Andrew
  Blog : andrewrea.co.uk
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  ysw

  Contributor

  2784 Points

  515 Posts

  Re: Why is HttpContext.Current.Server.MapPath invalid in a asynchronous function?

  Jul 08, 2007 11:21 PM|LINK

  Hi

  HttpContext.Current is only available on threads executing http requests.  When you invoke your method with BeginInvoke, your method is executed on another thread from the thread pool. This thread (while executing your method) is not associated with any HttpContexts (BeginInvoke does not propagate it).

  Moreover, if you don't wait for your method to complete in your page code, it is possible that your catchemailcallback will start executing when current context is already disposed.

  If you transfer execution to another thread via async delegate call, I would suggest passing all prepared paths to this method directly.

  -yuriy
  http://couldbedone.blogspot.com

   

  • Edited by ysw on Jul 08, 2007 11:23 PM
  • Marked as answer by mycwcgr on Jul 09, 2007 12:32 PM
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  hnbi4u

  Member

  4 Points

  2 Posts

  Re: Why is HttpContext.Current.Server.MapPath invalid in a asynchronous function?

  Jul 11, 2008 09:18 AM|LINK

   

   

   

  hello there,  

  i am getting {"Failed to map the path '/iCal/'."} exception when i tried using this statement

  string path = HttpContext.Current.Server.MapPath(@"\iCal\");

  any help???