json unmarshal

main.go

package main

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"net/http"

	"github.com/gorilla/mux"
)

type input struct {
	Foo string `json:"foo"`
}

func main() {
	r := mux.NewRouter()

	r.Methods("GET").Path("/").HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
		var i input
		if !getJSON(w, req, &i) {
			return
		}

		fmt.Printf("%+v\n", i)
	})

	if err := http.ListenAndServe(":9876", r); err != nil {
		panic(err)
	}
}

func getJSON(w http.ResponseWriter, req *http.Request, i interface{}) bool {
	b, err := ioutil.ReadAll(req.Body)
	if err != nil {
		w.WriteHeader(400)
		return false
	}

	defer req.Body.Close()

	err = json.Unmarshal(b, &i)
	if err != nil {
		w.WriteHeader(400)
		return false
	}

	return true
}