Accept and download stream content from ASP.NET Web API using HTTPClient

Question

I have an ASP.NET Web API action which creates a file and returns a stream content:

public HttpResponseMessage Get(string filePath)
{
    // create file
    var file = FileConverter.GenerateExcelFile(filePath);

    var stream = new FileStream(filePath, FileMode.Open);

    HttpResponseMessage result = new HttpResponseMessage(HttpStatusCode.OK);
    result.Content = new StreamContent(stream);
    result.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment");
    result.Content.Headers.ContentDisposition.FileName = Path.GetFileName(filePath);
    result.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
    return result;
}

I would like to use HttpClient to download the returned file. Here's what I have now:

    client.GetAsync(address).ContinueWith(
        (requestTask) =>
        {
             HttpResponseMessage response = requestTask.Result;

            // response.EnsureSuccessStatusCode();

            response.Content.ReadAsStreamAsync().ContinueWith(
                        (readTask) =>
                        { 
                            var stream = readTask.Result; 
                        });
        });

How do I force the actual download after getting the result?

Edit: I'm using ASP.NET 4.0 WebForms.

Did you ever find out an answer for this?

cjohns
– cjohns

2013-07-25 20:47:42 +00:00
Commented Jul 25, 2013 at 20:47 — cjohns
– cjohns, Commented Jul 25, 2013 at 20:47
@cjohns no, I did not find an answer.

Rivka
– Rivka

2013-07-26 07:03:40 +00:00
Commented Jul 26, 2013 at 7:03 — Rivka
– Rivka, Commented Jul 26, 2013 at 7:03

Josh · Accepted Answer · 2013-04-25 18:40:00Z

3

Have you thought about just calling :

client.GetByteArrayAsync(address)

instead to get the byte array result and then just save it to a memory stream?

Edit::

Try something like this:

var contentBytes = await client.GetByteArrayAsync(address);
Stream stream = new MemoryStream(contentBytes);

edited Apr 25, 2013 at 18:40

answered Apr 25, 2013 at 17:07

Josh

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2 Comments

Rivka Over a year ago

No, I haven't. I just tried replacing my GetAsync with GetByteArrayAsync, but got syntax errors. Simply running the one-line client.GetByteArrayAsync(address); threw "one or more exceptions have occured".

Rivka Over a year ago

Thanks but that's still giving me "one or more errors have occurred". Also, I'm using ASP.NET 4.0 (not 4.5). I also tried changing my action to return a ByteArrayContent, but it didn't make a difference. Note, when I call the Web API by pasing the URL in my browser, no error is thrown and the file is downloaded and shown in my browser. Just the HttpClient code doesn't seem to be working. (My original method didn't throw any errors.)

Darrel Miller · Accepted Answer · 2013-04-26 17:47:17Z

1

Why do you think the download has not happened?

By default when you do GetAsync HTTP client with create MemoryStream as a buffer with the result. ReadAsStreamAsync is just returning that buffered StreamContent.

Edit: You can create a file like this,

  using (FileStream fs = new FileStream("file.txt", FileMode.Create)) {
           stream.CopyTo(fs);
        }
    }

edited Apr 26, 2013 at 17:47

answered Apr 26, 2013 at 14:32

Darrel Miller

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8 Comments

Rivka Over a year ago

I don't think the API didn't return the Stream. I just simply need the user to get the file... so we need to do something with the stream. I can't use Response.WriteFile or something like because it gives me "Response is not available in this context."

Rivka Over a year ago

I'm missing something here...I get how to create the file...I need it to be downloaded...are you saying you can't actually download it to the browser in the same request? Hope my issue is clear.

Darrel Miller Over a year ago

@Rivka I'm confused, you said you want to use HttpClient. But now you are saying you want to use a browser. I don't understand your scenario.

Rivka Over a year ago

Are those two mutually exclusive? Let's put it this way: Forget the stream - after I get any result from the server via HttpClient (could be ReadAsAsync()), is it possible to download a file? Just like I would normally do with Response.ContentType = "application/octet-stream"; Response.AddHeader("Content-Disposition", String.Format("attachment;filename=\"{0}\"", file.Name)); Response.AddHeader("Content-Length", file.Length.ToString()); Response.WriteFile(file.FullName); Response.End(); This is a real simple question: get a response from a server using HttpClient and then download a file.

Darrel Miller Over a year ago

@Rivka Where is your HTTPClient code running? What user-agent do you want to use to download the file with? I honestly don't understand what you are trying to do.

|

user3285954 · Accepted Answer · 2014-03-22 17:17:01Z

-1

HttpClient runs on server side not in web browser so it's really confusing what you are trying to achieve here. If you really need to use HttpClient yoou can save the result stream to a file stream as you can read in comments.

If you want the file to be downloaded in a web browser you don't need and can't use HttpClient. As you've written in a comment it already works, just create a link what the user can click on. Or search for ajax download file.

answered Mar 22, 2014 at 17:17

user3285954

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