Need help adding a stop button --> HttpWebRequest

Question

I have a program that has a button called "research" when that button is pressed it reads from an input text box that may say " how to * "

It starts to pull auto suggestions from say google and the asterisk is replaced by each letter of the alphabet.

My question is:

I want a button to STOP the search. While it is in motion.

What would be the best way to accomplish this?

private void btnResearch_Click(object sender, RoutedEventArgs e)
        {            
            if (string.IsNullOrWhiteSpace(txtResearch.Text.Trim()))
            {
                MessageBox.Show("Please enter a search query", "Oops", MessageBoxButton.OK, MessageBoxImage.Exclamation);
                return;              
            }
            //Robin: Temporal fix to the multi asterisk
            if (txtResearch.Text.Trim().Count(s => s == '*') > 1)
            {
                MessageBox.Show("Too many asterisk", "Oops", MessageBoxButton.OK, MessageBoxImage.Exclamation);
                return;            
            }

            if (!ValidateLimitations())
            {
                return;
            }

            ((LongTailBot.MainWindow)App.Current.MainWindow).PlaySound("button_double_click.wav");

            this.chbSelAll.IsChecked = false;
            List<KeywordItem> keyList = new List<KeywordItem>();
            this.dgrResearch.ItemsSource = null;

            List<string> seetKeywords = SetupSeetKeywords(txtResearch.Text.Trim().Replace(" ", "%20"));
            if (seetKeywords.Count() < 1)
                return;

            foreach (string seetKey in seetKeywords)
            {
                this.txbResearch.Text = (seetKeywords.IndexOf(seetKey) + 1).ToString()
                    + "/" + seetKeywords.Count() + " " + seetKey.Replace("%20", " ");
                Application.Current.Dispatcher.Invoke(DispatcherPriority.Background,
                                                      new Action(delegate { }));

                HttpWebRequest request = (HttpWebRequest)WebRequest.Create(this.GetRequestUriString(seetKey));
                request.Method = "GET";
                request.UserAgent = @"Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.0; Trident/5.0)";
                WebResponse response = request.GetResponse();

                if (((HttpWebResponse)response).StatusDescription.Trim().ToUpper() == "OK")
                {
                    using (Stream dataStream = response.GetResponseStream())
                    {
                        using (StreamReader reader = new StreamReader(dataStream))
                        {
                            string responseFromServer = reader.ReadToEnd();

                            var keywordsFound = this.GetKeywordsFound(responseFromServer);
                            foreach (var key in keywordsFound)
                            {
                                keyList.RemoveAll(k => k.Keyword == key);                                                                
                                keyList.Add(new KeywordItem() { Checked = false, Keyword = key });

                                Application.Current.Dispatcher.Invoke(DispatcherPriority.Background,
                                          new Action(delegate { }));                                
                            }

                        }
                    }
                    if (keyList.Count > 0)
                    {
                        dgrResearch.ItemsSource = null;
                        dgrResearch.ItemsSource = keyList;
                        dgrResearch.ScrollIntoView(dgrResearch.Items[dgrResearch.Items.Count - 1]);                        
                    }
                }

                response.Close();                
            }

            this.txbResearch.Text = this.dgrResearch.Items.Count.ToString() + " POPULAR PHRASES AVAILABLE!";            
            this.chbSelAll.IsChecked = dgrResearch.Items.Count > 0? true : false;
            ((LongTailBot.MainWindow)App.Current.MainWindow).PlaySound("abstractbtn.wav");
        }

Answer 1

You should use the BeginGetResponse method and pass your response handling as the Callback parameter. Then in your Cancel button, you call the Abort Method.

Didnt try it, but that should generally work.