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20

I'm working on a web service using ASP.NET MVC's new WebAPI that will serve up binary files, mostly .cab and .exe files.

The following controller method seems to work, meaning that it returns a file, but it's setting the content type to application/json:

public HttpResponseMessage<Stream> Post(string version, string environment, string filetype)
{
    var path = @"C:\Temp\test.exe";
    var stream = new FileStream(path, FileMode.Open);
    return new HttpResponseMessage<Stream>(stream, new MediaTypeHeaderValue("application/octet-stream"));
}

Is there a better way to do this?

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3 Answers

up vote 69 down vote accepted

Try using a simple HttpResponseMessage, with a StreamContent inside, which should work fine.

public HttpResponseMessage Post(string version, string environment,
    string filetype)
{
    var path = @"C:\Temp\test.exe";
    HttpResponseMessage result = new HttpResponseMessage(HttpStatusCode.OK);
    var stream = new FileStream(path, FileMode.Open);
    result.Content = new StreamContent(stream);
    result.Content.Headers.ContentType = 
        new MediaTypeHeaderValue("application/octet-stream");
    return result;
}
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Nice, Carlos. That worked! – Josh Earl Mar 4 '12 at 13:48
14  
Would you happen to know when the stream gets closed? I am assuming the framework ultimately calls HttpResponseMessage.Dispose(), which in turn calls HttpResponseMessage.Content.Dispose() effectively closing the stream. – Steve Guidi Apr 20 '12 at 18:36
9  
Steve - you're correct and I verified by adding a breakpoint to FileStream.Dispose and running this code. The framework calls HttpResponseMessage.Dispose, which calls StreamContent.Dispose, which calls FileStream.Dispose. – Dan Aug 22 '12 at 20:02
@carlosfigueira Would you mind putting these using comments in your answer? – sennett Jun 19 at 3:27
2  
You can't really add a using to either the result (HttpResponseMessage) or the stream itself, since they'll still be used outside the method. As @Dan mentioned, they're disposed by the framework after it's done sending the response to the client. – carlosfigueira Jun 19 at 16:18
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up vote 3 down vote

The overload that you're using sets the enumeration of serialization formatters. You need to specify the content type explicitly like:

httpResponseMessage.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
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Thanks for the reply. I tried this out, and I'm still seeing Content Type: application/json in Fiddler. The Content Type appears to be set correctly if I break before returning the httpResponseMessage response. Any more ideas? – Josh Earl Mar 3 '12 at 14:34
up vote 1 down vote

You could try

httpResponseMessage.Content.Headers.Add("Content-Type", "application/octet-stream");
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