handlers.go

package main

import (
	"encoding/json"
	"github.com/gorilla/mux"
	"net/http"
	"strconv"
)

func respondWithError(w http.ResponseWriter, code int, message string) {
	respondWithJSON(w, code, map[string]string{"error": message})
}

func respondWithJSON(w http.ResponseWriter, code int, payload interface{}) {
	response, _ := json.Marshal(payload)

	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(code)
	w.Write(response)
}

func (a *App) getProduct(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)
	id, err := strconv.Atoi(vars["id"])
	if err != nil {
		respondWithError(w, http.StatusBadRequest, "Invalid product ID")
		return
	}

	p, err := getProduct(a.DB, id)
	if err != nil {
		respondWithError(w, http.StatusNotFound, "Product not found")
		return
	}

	respondWithJSON(w, http.StatusOK, p)
}