json.go

package main

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

func respondWithJSON(w http.ResponseWriter, code int, payload interface{}) {
	dat, err := json.Marshal(payload)
	if err != nil {
		log.Printf("Error marshalling payload, JSON responce: %v", payload)
		w.WriteHeader(500)
		return
	}
	w.Header().Add("Content-Type", "application/json")
	w.WriteHeader(code)
	w.Write(dat)
}

func respondWithError(w http.ResponseWriter, code int, message string) {
	if code > 499 {
		log.Println("Responding with 5XX root:", message)
	}

	type errorResponse struct {
		Error string `json:"error"`
	}

	respondWithJSON(
		w,
		code,
		errorResponse{
			Error: message,
		},
	)
}