Golang : Upload file from web browser to server

Recently, I came across a question on Go programming language Facebook group on how to upload file with http://golang.org/*

In this tutorial, we will use Go and HTML to achieve the following :

  • A simple HTML file upload form to upload file to server

  • Go program on server side to receive the uploaded file

  • Verify the uploaded file location and content on server.

1) HTML file upload form to upload file to server - goupload.html

  <title>Go upload</title>

  <form action="http://localhost.com:8080/receive" method="post" enctype="multipart/form-data">
  <label for="file">Filename:</label>
  <input type="file" name="file" id="file">
  <input type="submit" name="submit" value="Submit">


NOTE : The input id file will be captured by the uploadHandler's FormFile function.

2) Go program on server side to receive the uploaded file - receive.go

 package main

 import (

 func uploadHandler(w http.ResponseWriter, r *http.Request) {

  // the FormFile function takes in the POST input id file
  file, header, err := r.FormFile("file")

  if err != nil {
 fmt.Fprintln(w, err)

  defer file.Close()

  out, err := os.Create("/tmp/uploadedfile")
  if err != nil {
 fmt.Fprintf(w, "Unable to create the file for writing. Check your write access privilege")

  defer out.Close()

  // write the content from POST to the file
  _, err = io.Copy(out, file)
  if err != nil {
 fmt.Fprintln(w, err)

  fmt.Fprintf(w, "File uploaded successfully : ")
  fmt.Fprintf(w, header.Filename)

 func main() {
  http.HandleFunc("/", uploadHandler)
  http.ListenAndServe(":8080", nil)

the code above uses the FormFile function to process the POST array and focus on file input

run receive.go at the server
> go run receive.go

browse goupload.html and upload a file of your choice. The uploaded file will be named uploadedfile

3) Verify the uploaded file location and content on the server.

See if the file is uploaded to the /tmp with ls command and cat to see the content

Visit https://www.socketloop.com/tutorials/golang-how-to-verify-uploaded-file-is-image-or-allowed-file-types for further information on how to verify or detect the uploaded file type.



  See also : Upload multiple files with Go

Tags : golang upload file

Adam Ng By Adam Ng

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