Golang : Upload/Receive file progress indicator


Tags : golang upload progress-bar

It is always nice to have a progress bar telling us how long to wait for the upload or download to complete. In this tutorial, we will learn how to display a text based progress indicator for receiving file.

Note : This is a server side program(console/terminal) and not for client side (web browser)

1) Run this code on your local machine.

 package main

 import (
 "fmt"
 "io"
 "net/http"
 "os"
 "time"
 )

 func uploadPage(w http.ResponseWriter, r *http.Request) {
 w.Write([]byte(fmt.Sprintf("<html><title>Go upload</title><body><form action='http://localhost:8080/receive' method='post' enctype='multipart/form-data'><label for='file'>Filename:</label><input type='file' name='file' id='file'><input type='submit' value='Upload' ></form></body></html>")))
 }

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

 mr, err := r.MultipartReader()
 if err != nil {
 fmt.Fprintln(w, err)
 return
 }
 length := r.ContentLength

 //ticker := time.Tick(time.Millisecond) // <-- use this in production
 ticker := time.Tick(time.Second) // this is for demo purpose with longer delay

 for {

 var read int64
 var p float32
 part, err := mr.NextPart()

 if err == io.EOF {
 fmt.Printf("\nDone!")
 break
 }

 dst, err := os.OpenFile("upload.jpg", os.O_WRONLY|os.O_CREATE, 0666)

 if err != nil {
 return
 }

 for {

 buffer := make([]byte, 100000)
 cBytes, err := part.Read(buffer)
 if err == io.EOF {
 fmt.Printf("\nLast buffer read!")
 break
 }
 read = read + int64(cBytes)

 //fmt.Printf("\r read: %v  length : %v \n", read, length)

 if read > 0 {
 p = float32(read*100) / float32(length)
 //fmt.Printf("progress: %v \n", p)
 <-ticker
 fmt.Printf("\rUploading progress %v", p) // for console
 dst.Write(buffer[0:cBytes])
 } else {
 break
 }

 }
 }
 }

 func main() {
 mux := http.NewServeMux()
 mux.HandleFunc("/", uploadPage)
 mux.HandleFunc("/receive", uploadProgress)

 http.ListenAndServe(":8080", mux)
 }

2 ) open up your browser and point to http://localhost:8080

3) You will see a simple form for you to upload a file. Choose a file and press upload button.

4) At this point, you should be able to see something like this

$ go run receive.go

Uploading progress 17.9386945

and it will keep updating until the upload from browser to the server is completed.

  See also : Golang : Upload file from web browser to server



Tags : golang upload progress-bar

By Adam Ng

IF you gain some knowledge or the information here solved your programming problem. Please consider donating to the less fortunate or some charities that you like. Apart from donation, planting trees, volunteering or reducing your carbon footprint will be great too.


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