Question

I’m not sure if I’m doing this correctly, but I have the following code that I am using (click button1, do the _DoWork). The question is this: how do I call the UI to get the values of textbox1 and textbox2 as they cannot be called as they are on a different thread. Should I be using dispatchers?

    private void button1_Click(object sender, RoutedEventArgs e)
    {
        if (textBox1.Text == "")
        {
            MessageBox.Show("Please enter a username and password", "Error", MessageBoxButton.OK, MessageBoxImage.Warning);
        }
        else
        {
            bw.DoWork += new DoWorkEventHandler(bw_DoWork);
            bw.RunWorkerAsync();
        }
    }

    private void bw_DoWork(object sender, DoWorkEventArgs e)
    {
        Console.WriteLine("asd");
        UserManagement um = new UserManagement(sm.GetServerConnectionString());
        if (um.AuthUser(textBox1.Text, textBox2.Password))
        {
            MainWindow mw = new MainWindow();
            mw.Show();
            this.Close();
        }
        else
        {
            if (um.Timeout)
            {
                MessageBox.Show("Could not connect to server, please check your configuration", "Error", MessageBoxButton.OK, MessageBoxImage.Error);
            }
            else
            {
                MessageBox.Show("Incorrect username or password", "Error", MessageBoxButton.OK, MessageBoxImage.Error);
            }

        }
    }

Should I be using background worker?

Answer 1

You can pass data into the worker via the argument of the RunWorkerAsync call and pass data out via DoWorkEventArgs.Result…

  class AuthUserData
  {
    public string Name;
    public string Password;
  }

  private void button1_Click(object sender, EventArgs e)
  {
     var authData = new AuthUserData() { Name = textBox1.Text, Password = textBox2.Text };
     worker.RunWorkerAsync(authData);
  }

  void worker_DoWork(object sender, DoWorkEventArgs e)
  {
     // On the worker thread...cannot make UI calls from here.
     var authData = (AuthUserData)e.Argument;
     UserManagement um = new UserManagement(sm.GetServerConnectionString());
     e.Result = um;
     e.Cancel = um.AuthUser(textBox1.Text, textBox2.Password));
  }

  void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
  {
     // Back on the UI thread....UI calls are cool again.
     var result = (UserManagement)e.Result;
     if (e.Cancelled)
     {
        // Do stuff if UserManagement.AuthUser succeeded.
     }
     else
     {
        // Do stuff if UserManagement.AuthUser failed.
     }
  }