exceptions

Maxxim · February 12th, 2008, 01:24 PM

Hello!

In one page I see this:

Code:

                    If Me.User.Identity.IsAuthenticated AndAlso _
                        (Me.User.IsInRole("Administrators") Or _
                        Me.User.IsInRole("Editors")) Then

                        dvwArticle.ChangeMode(DetailsViewMode.Edit)
                    Else
                        Throw New SecurityException( _
                            "You are not allowed to edit existent articles!")
                    End If

But, all we have the "custom errors="On" I suppose...

So, the user will never read "You are not allowed to edit existent articles!" !!
He will only read that one error occurred :( And he will think that the page have a lot of error's!

It's possible to show, in the error.aspx the exception message = "You are not allowed to edit existent articles!"

Thanks!
Max

Lee Dumond · February 12th, 2008, 03:30 PM

Yes, it's possible to show any properties of an exception you want in a custom error page.

It's not a straightforward as it may appear at first. That's because once the custom error page is displayed, the exception is considered "handled" and is immediately disposed of, so it's too late to get a reference to it at that point.

So, you need to somehow persist the exception before the custom error page is served, then get a reference to it from there.

htorres · October 15th, 2008, 10:02 PM

Hi, I have the same problem, did you find a way to do it?
Thanks
Horacio

Lee Dumond · October 18th, 2008, 12:34 PM

As I said before, you have to persist the exception before the custom error page is served. The best way to do that is to catch it in the Global.asax Application_Error event handler, which always fires before the custom error page.

So, in Global.asax, you could do something like this:

void Application_Error(Object sender, EventArgs e)
   {
      Exception ex = Server.GetLastError();
      Session["LastError"] = ex;
      Response.Redirect("/TBH_Web/Error.aspx", false);
      Server.ClearError();
   }

What this does is get the exception that caused the Application_Error event to fire. Then it stores the exception in the session. It then redirects to the custom error page, and clears the error so that it doesn't bubble up to the web.config customErrors handler.

Now, all you have to do is to retrieve the exception from the session in Error.aspx. You can add that code to the already existing Page_Load event handler:

protected void Page_Load(object sender, EventArgs e)
      {
         if (Session["LastError"] != null)
         {
            lblError.Visible = true;
            lblError.Text = (Session["LastError"] as Exception).Message;
            Session.Remove("LastError");
         }

         lbl404.Visible = (this.Request.QueryString["code"] != null && this.Request.QueryString["code"] == "404");
         lbl408.Visible = (this.Request.QueryString["code"] != null && this.Request.QueryString["code"] == "408");
         lbl505.Visible = (this.Request.QueryString["code"] != null && this.Request.QueryString["code"] == "505");
         lblError.Visible = (string.IsNullOrEmpty(this.Request.QueryString["code"]));
      }

Tah-dah! The error message should now be displayed in Error.aspx.

Hope this helps.