https://medium.com/statuscode/how-i-write-go-http-services-after-seven-years-37c208122831

server.go

func (s *server) respond(w http.ResponseWriter, r *http.Request, data interface{}, status int) {
	w.WriteHeader(status)
	if data != nil {
		err := json.NewEncoder(w).Encode(data)
		s.logf("json encode %s", err)
	}
}

func (s *server) decode(w http.ResponseWriter, r *http.Request, v interface{}) error {
	return json.NewDecoder(r.Body).Decode(v)
}