Golang : Get checkbox or extract multipart form data value example

This tutorial is a slight modification on the previous tutorial on the how to upload multiple files and this time we will learn how to get the values of a multi-part form data.

To extract the values from a multi-part form is easy after parsing with ParseMultipartForm() and with request.FormValue()

The example below will show you how to get the value of a checkbox. Run this code, point your browser to your web server port 8080 and you should see a simple form. Click on the check box and press submit button. Rerun the process again but this time WITHOUT ticking the check box.

Here you go!

 package main 

 import ( 

 func Home(w http.ResponseWriter, r *http.Request) { 
 html := `<html>
  <title>Go upload</title>

  <form action="http://example.com:8080/getcheckbox" method="post" enctype="multipart/form-data">
  <label for="file">Filenames:</label>
  <input type="file" name="multiplefiles" id="multiplefiles" multiple>
  <input type="checkbox" name="compress" value="compressboxchecked">
  <input type="submit" name="submit" value="Submit">


 //output to web browser(client)



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

 err := r.ParseMultipartForm(200000) // grab the multipart form

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

 // get the value of checkbox

 // if the checkbox is not ticked, the value will be empty

 fmt.Fprintln(w, r.FormValue("compress"))
 fmt.Println("Compress the file ? : ", r.FormValue("compress"))


 func main() {

 mux := http.NewServeMux()

 mux.HandleFunc("/", Home)
 mux.HandleFunc("/getcheckbox", GetCheckBox)

 http.ListenAndServe(":8080", mux)




  See also : Upload multiple files with Go

By Adam Ng

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