C# - Catch WebException While Posting XML Async

Question

I am POSTING XML data using WebClient.

  public string uploadXMLData(string destinationUrl, string requestXml)
        {
            try
            {

                System.Uri uri = new System.Uri(destinationUrl);
                using (WebClient client = new WebClient())
                {
                    client.Headers.Add("content-type", "text/xml");
                    var response = client.UploadString(destinationUrl, "POST", requestXml); 
                }
            }

            catch (WebException webex)
            {

                WebResponse errResp = webex.Response;
                using (Stream respStream = errResp.GetResponseStream())
                {
                    StreamReader reader = new StreamReader(respStream);
                    string text = reader.ReadToEnd();
                }
            }
            catch (Exception e)
            { }

            return null;
        }

When there is an error, I catch it as WebException, and I read the Stream in order to know what the XML response is.

What I need to do, is post the XML data to the URL in Async. So I changed the function:

public string uploadXMLData(string destinationUrl, string requestXml)
{
    try
    {

        System.Uri uri = new System.Uri(destinationUrl);
        using (WebClient client = new WebClient())
        {

            client.UploadStringCompleted
       += new UploadStringCompletedEventHandler(UploadStringCallback2); 
            client.UploadStringAsync(uri, requestXml);
        }
    }

    catch (Exception e)
    { }

    return null;
}


void UploadStringCallback2(object sender, UploadStringCompletedEventArgs e)
{            
    Console.WriteLine(e.Error);
}

How can I catch the WebException now and read the XML response?

Can I throw e.Error?

Any help would be appreciated

see this link...it gives details about how to handle exception with an aync implementation. http://stackoverflow.com/questions/5383310/catch-an-exception-thrown-by-an-async-method — Prashant, Jul 13 '15 at 16:27
@Prashant Thank you. I want it to work with UploadStringAsync... — HelpASisterOut, Jul 14 '15 at 09:07

score 2 · Accepted Answer · answered Jul 14 '15 at 12:46

I found the solution:

   void UploadStringCallback2(object sender, UploadStringCompletedEventArgs e)
    {
        if (e.Error != null)
        {
            object objException = e.Error.GetBaseException();

            Type _type = typeof(WebException);
            if (_type != null)
            {
                WebException objErr = (WebException)e.Error.GetBaseException();
                WebResponse rsp = objErr.Response;
                using (Stream respStream = rsp.GetResponseStream())
                {
                    StreamReader reader = new StreamReader(respStream);
                    string text = reader.ReadToEnd();
                }
                throw objErr;
            }
            else
            {
                Exception objErr = (Exception)e.Error.GetBaseException();
                throw objErr;
            }
        }

     }

You should accept your own answer, so the question is marked as answered. This will also signal others that this is indeed the correct solution to the problem. — nestedloop, Oct 27 '15 at 07:57

C# - Catch WebException While Posting XML Async

1 Answers1