How to stop webrequest in windows phone 8.1 c#

Question

I have just started developing an application targeting windows phone 8.1. In my application I am calling my web service and getting results from it. But when i click the hardware back button while the web request is processing the page is redirecting to the previous page, but I couldn't stop processing the Web request. The result is getting displayed when it got the response.

My code is here:

  private async void accAcctDet_Click(object sender, RoutedEventArgs e)
    {
                string selected = acct[cmbAccDetail.SelectedIndex];
                string maskselect = cmbAccDetail.SelectedItem.ToString();
                prog.Visibility = Visibility.Visible;    
                acctdetails obj = new acctdetails();
                var result = await obj.GetToken(selected);                   
                if (result.Substring(0, 2) == "Se" || result.Substring(0, 2) == "Ki")
                {
                    prog.Visibility = Visibility.Collapsed;
                    MessageDialog msgbox = new MessageDialog("Service Unavailable. Please try again later", "e-Book!");
                    await msgbox.ShowAsync();
                    ContentRoot.Visibility = Visibility.Visible;
                    myCommandBar.Visibility = Visibility.Visible;
                }
                else
                {
                    prog.Visibility = Visibility.Collapsed;
                    this.Frame.Navigate(typeof(acctdetinfo), result);
                }
    }
    public async Task<string> GetToken(string selected)
    {
        string postData = "selAcct=" + selected;
        var res = await post("myparameter", postData);
        return res;
    }
    private async Task<string> post(string url, string postdata)
    {
        var request = WebRequest.Create(new Uri("myurl.com" + url)) as HttpWebRequest;
        request.Method = "POST";
        request.ContentType = "application/json";
        byte[] data = Encoding.UTF8.GetBytes(postdata);
        //request.ContentLength = data.Length;
        using (var requestStream = await Task<Stream>.Factory.FromAsync(request.BeginGetRequestStream, request.EndGetRequestStream, request))
        {
            await requestStream.WriteAsync(data, 0, data.Length);
        }
        WebResponse responseObject = await Task<WebResponse>.Factory.FromAsync(request.BeginGetResponse, request.EndGetResponse, request);
        var responseStream = responseObject.GetResponseStream(); 
        var sr = new StreamReader(responseStream);
        string received = await sr.ReadToEndAsync();
        return received;
    }

I need to stop the request once the user clicked the hardware back button.

Any help would be highly appreciated

Use a cancellation token in conjunction with the code in this answer: http://stackoverflow.com/questions/19211972/getresponseasync-does-not-accept-cancellationtoken — Barnstokkr, Aug 12 '15 at 09:15

score 0 · Accepted Answer · edited May 23 '17 at 11:43

0

You could either add a bool to check if the user has navigated away

//Inside OnNavigatingFrom
...
hasNavigatedAway = true;
...

//Inside post(string url, string postdata)
if(hasNavigatedAway) return;

or you can do something with a CancellationToken as answered here.

edited May 23 '17 at 11:43

Community

1
1

answered Aug 12 '15 at 08:18

Jon G Stødle

3,844
1
16
22

Thanks for the post. Will check this and let you know. – JMR Aug 13 '15 at 04:06

How to stop webrequest in windows phone 8.1 c#

1 Answers1