JSON and Middleware

main.go

package main

import (
	"encoding/json"
	"net/http"

	"github.com/codegangsta/negroni"
	"github.com/julienschmidt/httprouter"
)

type Book struct {
	Title  string
	Author string
}

type User struct {
	Name  string
	Email string
}

func main() {
	n := negroni.Classic()

	mux := httprouter.New()
	mux.GET("/users", Users)
	mux.GET("/books", Books)

	n.UseFunc(Auth)
	n.UseHandler(mux)
	n.Run(":8080")
}

func Users(rw http.ResponseWriter, r *http.Request, p httprouter.Params) {
	user := User{
		Name:  "Jeremy",
		Email: "jeremy@codegangsta.io",
	}

	json.NewEncoder(rw).Encode(user)
}

func Books(rw http.ResponseWriter, r *http.Request, p httprouter.Params) {
	book := Book{
		Title:  "Building Web apps in Go",
		Author: "Jeremy",
	}

	data, err := json.Marshal(book)
	if err != nil {
		http.Error(rw, err.Error(), 500)
		return
	}

	rw.Header().Set("Content-Type", "application/json")
	rw.Write(data)
}

func Auth(rw http.ResponseWriter, r *http.Request, next http.HandlerFunc) {
	if r.URL.Query().Get("password") == "secret123" {
		next(rw, r)
	} else {
		http.Error(rw, "Not Authorized", 401)
	}
}