Golang : How to stream file to client(browser) or write to http.ResponseWriter?
Problem :
You have a file - such as a PDF or MP3 file that you want to stream/download straight to your user's web browser(client). How to achieve that in Golang?
Solution :
Convert the files to buffer with bytes.NewBuffer()
function and write to http.ResponseWriter.
Code fragment taken from previous tutorial on how to generate PDF file.
func PDF(w http.ResponseWriter, r *http.Request) {
...
// grab the generated receipt.pdf file and stream it to browser
streamPDFbytes, err := ioutil.ReadFile("./receipt.pdf")
if err != nil {
fmt.Println(err)
os.Exit(1)
}
b := bytes.NewBuffer(streamPDFbytes)
// stream straight to client(browser)
w.Header().Set("Content-type", "application/pdf")
if _, err := b.WriteTo(w); err != nil { // <----- here!
fmt.Fprintf(w, "%s", err)
}
w.Write([]byte("PDF Generated"))
}
See also : Golang : Create PDF file from HTML file
By Adam Ng
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