Question

I got a VERY weird problem happening with ALL my DocumentCompleteEventHandlers.

Say I have a very simple handler:

void Download_Complete_Handler(object sender, WebBrowserDocumentCompletedEventArgs e)
        {
            string link = webBrowser1.Url.ToString();
            Regex rgx = new Regex("(^https://mysite.com/)");
            if (rgx.IsMatch(link)) // have made it this way so that I don't remove the handler for every page. Pretty handy.
            {
                string name = choosename(); // my custom function to create new name
                string surname = choosesurname(); // my custom function to create new surname
                Random rand = new Random();

                webBrowser1.Document.GetElementById("id").Focus();
                SendKeys.SendWait(name + "." + surname + rand.Next(0, 9999).ToString());

                name = "";
                surname = "";
            }
        }

And I call this handler in following function which is called on button click:

void myfunction()
{
  try
  {
    webBrowser1.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(Download_Complete_Handler);
    webBrowser1.Navigate("mysite.com");
  }
  catch(Exception ex)
  {
    log(ex);// my custom log function
  }
}

Now, when I first launch the program, and I click the button to trigger the handler, all works OK: Webbrowser is navigated, once page is loaded – the needed field is filled in.
Now let’s say, I click the same button once again, so that all process starts all over again. This time the handler is called twice: once page is loaded, the field is filled two times. Third click will trigger the handler three times, etc.

Do you know what I’m doing wrong?

Answer 1

Yes – you’re adding a new handler every time the button is clicked. The old handlers aren’t removed – they’ll stick around forever (unless you remove them explicitly, of course).

Add the handler once, and then just perform navigation in the button click.

As an aside, it’s generally not a good idea to create multiple instances of Random like this. See my article on the topic.