Web Application to generate QR code in Golang
A Quick Response code is a two-dimensional pictographic code used for its fast readability and comparatively large storage capacity. The code consists of black modules arranged in a square pattern on a white background. The information encoded can be made up of any kind of data (e.g., binary, alphanumeric, or Kanji symbols).
The basic example of web application to generate bar-code. The algorithm or internal logic to generate bar-code is available in third-party bar-code package. Here the goal is to show an example how to use a package and create a web-application.
1. Install required package
The Barcode package can be used to create different types of bar-codes. You can install this package by executing the following command in your git bash terminal:
go get github.com/boombuler/barcode
2. Development
2.1 Source code of main.go
The main function begins with a call to http.HandleFunc, which tells the http package to handle all requests to the web root ("/") with homeHandler. The function homeHandler is of the type http.HandlerFunc. It takes an http.ResponseWriter and an http.Request as its arguments.
The function viewCodeHandler that will allow users to view a generated QR-code in new page. It will handle URLs prefixed with "/generator/". The function template.ParseFiles will read the contents of generator.html and return a *template.Template.
package main
import (
"image/png"
"net/http"
"text/template"
"github.com/boombuler/barcode"
"github.com/boombuler/barcode/qr"
)
type Page struct {
Title string
}
func main() {
http.HandleFunc("/", homeHandler)
http.HandleFunc("/generator/", viewCodeHandler)
http.ListenAndServe(":8080", nil)
}
func homeHandler(w http.ResponseWriter, r *http.Request) {
p := Page{Title: "QR Code Generator"}
t, _ := template.ParseFiles("generator.html")
t.Execute(w, p)
}
func viewCodeHandler(w http.ResponseWriter, r *http.Request) {
dataString := r.FormValue("dataString")
qrCode, _ := qr.Encode(dataString, qr.L, qr.Auto)
qrCode, _ = barcode.Scale(qrCode, 512, 512)
png.Encode(w, qrCode)
}
The FormValue function will gives the value of dataString input field which will be used to generate the QR code using Encode function.
2.2 Source code of generator.html.
A template file containing the HTML form.
<h1>{{.Title}}</h1>
<div>Please enter the string you want to QRCode.</div>
<form action="generator/" method=post>
<input type="text" name="dataString">
<input type="submit" value="Submit">
</form>
3. Execution
Using command line or putty run command "go run main.go"
You will see an output like the image below.
