golang webapp example

main.go

package main

import (
	"context"
	"fmt"
	"log"
	"math/rand"
	"net/http"
	"os"
	"time"

	"github.com/dictyBase/go-middlewares/middlewares/logrus"
	"github.com/rs/cors"
	"gopkg.in/codegangsta/cli.v1"
)

func main() {
	app := cli.NewApp()
	app.Name = "routertest"
	app.Usage = "Test the httprouter with net/http wrapping"
	app.Version = "1.0.0"
	app.Flags = []cli.Flag{
		cli.IntFlag{
			Name:  "port, p",
			Usage: "server port",
			Value: 9998,
		},
	}
	app.Action = TestRouterAction
	app.Run(os.Args)
}

func TestRouterAction(c *cli.Context) error {
	r := NewRouter()
	cr := cors.New(cors.Options{
		AllowedOrigins:     []string{"*"},
		AllowCredentials:   true,
		OptionsPassthrough: true,
		Debug:              true,
	})
	lchain := NewChain(logrus.NewLogger().LoggerMiddlewareFn)
	r.Get("/whisky/:brand", lchain.ThenFunc(WhiskyHandler))
	r.Get("/exercise/:name", lchain.Append(CorsAdapter(cr), InjectSetsMiddle).ThenFunc(ExerciseHandler))
	log.Printf("Starting web server on port %d\n", c.Int("port"))
	log.Fatal(http.ListenAndServe(fmt.Sprintf(":%d", c.Int("port")), r.Router))
	return nil
}

// middlewares
func InjectSetsMiddle(fn http.HandlerFunc) http.HandlerFunc {
	nfn := func(w http.ResponseWriter, r *http.Request) {
		rd := rand.New(rand.NewSource(time.Now().UnixNano()))
		ctx := context.WithValue(r.Context(), "sets", rd.Intn(10))
		fn(w, r.WithContext(ctx))
	}
	return nfn
}

// final handlers
func WhiskyHandler(w http.ResponseWriter, r *http.Request) {
	params := Params(r)
	fmt.Fprintf(w, "I love whisky %s!\n", params.ByName("brand"))
}

func ExerciseHandler(w http.ResponseWriter, r *http.Request) {
	sets, ok := r.Context().Value("sets").(int)
	if !ok {
		http.Error(w, "unable to retrieve context", http.StatusInternalServerError)
		return
	}
	fmt.Fprintf(w, "I Love doing %s exercise! for %d sets\n", Params(r).ByName("name"), sets)
}

func CorsAdapter(c *cors.Cors) MiddlewareFn {
	fn := func(fn http.HandlerFunc) http.HandlerFunc {
		ifn := func(w http.ResponseWriter, r *http.Request) {
			c.HandlerFunc(w, r)
			fn(w, r)
		}
		return ifn
	}
	return fn
}