Golang : Progress bar with ∎ character

This tutorial is add on to the previous tutorial on how upload/receive progress indicator. Just a slight modification, where the progress is indicated by ∎ character and % completed.

NOTE : To add % sign after %v, use two % symbols.

Here you go :

 package main

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

 const (
 barChar = "∎"
 )

 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
 }

 var barLen int

 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)
 barLen = int(p)

 //fmt.Printf("progress: %v \n", strings.Repeat(barChar,barLen))
 <-ticker

 fmt.Printf("\rStatus: %v [%v%%]", strings.Repeat(barChar, barLen), p)
 //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)
 }

Sample output :

go run uploadprogress.go

Status: ∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎∎ [99.915634%]

Last buffer read!

Golang : Progress bar with ∎ character

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See also : Golang : Upload/Receive file progress indicator

By Adam Ng

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