C# Download file from webservice

Question

I have a web service, like this example for downloading a zip file from the server. When i open the URL through web browsers,I can download the zip file correctly. The problem is when I try to download the zip file through my desktop application. I use the following code to download:

WebClient webClient = new WebClient();
webClient.DownloadFileCompleted += new AsyncCompletedEventHandler(Completed);
webClient.DownloadProgressChanged += new DownloadProgressChangedEventHandler(ProgressChanged);
webClient.DownloadFileAsync(new Uri(@"http://localhost:9000/api/file/GetFile?filename=myPackage.zip"), @"myPackage.zip");

After testing this, I get the myPackage.zip downloaded, but it is empty, 0kb. Any help about this or any other server code + client code example?

just a sanity check here: are you awaiting for your async request to finish? — Alexander Toptygin
– Alexander Toptygin, Commented Jul 31, 2018 at 14:24
is ProgressChanged ever called? verify in a debugger. if the thread (or the host process) terminates before the first chunk is transmitted, download will be aborted which would explain the zero size file. — Cee McSharpface
– Cee McSharpface, Commented Jul 31, 2018 at 14:25
@AlexanderToptygin Does he need to, though, if he's responding to events? — Kenneth K.
– Kenneth K., Commented Jul 31, 2018 at 14:27
May you use the DownloadFile instead of DownloadFileAsync, Just to be sure. And tell us if it fix the issue ? — Drag and Drop
– Drag and Drop, Commented Jul 31, 2018 at 14:28
I am not using await, it says "Cannot await void". The progress changed isn't called ever, but the Complete yes. — Adnand
– Adnand, Commented Jul 31, 2018 at 14:29

Denys Prodan · Accepted Answer · 2018-07-31 14:54:10Z

11

You can try to use HttpClient instead. Usually, it is more convenient.

        var client = new HttpClient();
        var response = await client.GetAsync(@"http://localhost:9000/api/file/GetFile?filename=myPackage.zip");

        using (var stream = await response.Content.ReadAsStreamAsync())
        {
            var fileInfo = new FileInfo("myPackage.zip");
            using (var fileStream = fileInfo.OpenWrite())
            {
                await stream.CopyToAsync(fileStream);
            }
        }

answered Jul 31, 2018 at 14:54

Denys Prodan

2132 silver badges10 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Colin Wu Over a year ago

Exactly what I needed. Thanks. (Just as an aside, "convenient" is relative. I could have done all this in one line of code in Perl, using LWP::UserAgent module, but then we have to work with what we have.) :-)

Trisped Over a year ago

This is good, though it should be called out that client should be reused rather than making a new instance and disposing after each use. This article explains why

Collectives™ on Stack Overflow

C# Download file from webservice

1 Answer 1

2 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related