To make the browser open the download dialog, add a
Content-Type headers to the response:
w.Header().Set("Content-Disposition", "attachment; filename=WHATEVER_YOU_WANT") w.Header().Set("Content-Type", r.Header.Get("Content-Type"))
Do this BEFORE sending the content to the client. You might also want to copy the
Content-Length header of the response to the client, to show proper progress.
To stream the response body to the client without fully loading it into memory (for big files this is important) - simply copy the body reader to the response writer:
io.Copy is a nice little function that take a reader interface and writer interface, reads data from one and writes it to the other. Very useful for this kind of stuff!
I've modified your code to do this: http://play.golang.org/p/v9IAu2Xu3_