ใช้ Fiber

go get github.com/gofiber/fiber/v2
go get github.com/lib/pq

// ประกาศตัวแปร global สำหรับเรียกใช้ database
var db *sql.DB

func SetupDatabase() *sql.DB {
  const connectionString = "user=postgres password=yourpassword dbname=yourdbname sslmode=disable"
  db, err := sql.Open("postgres", connectionString)
  if err != nil {
    log.Fatal(err)
  }

  if err = db.Ping(); err != nil {
    log.Fatal(err)
  }

  return db
}

// ประกาศ struct Product สำหรับการรับ request
type Product struct {
  ID       int    `json:"id"`
  Name     string `json:"name"`
  Price    int    `json:"price"`
  Category string `json:"category"`
}

func main() {
  app := fiber.New()
  db = SetupDatabase()
  defer db.Close()

  // ใส่ API ตรงตำแหน่งนี้

  app.Listen(":3000")
}

func CreateProduct(c *fiber.Ctx) error {
  p := new(Product)
  if err := c.BodyParser(p); err != nil {
    return err
  }

  // Insert product into database
  _, err := db.Exec("INSERT INTO products (name, price, category) VALUES ($1, $2, $3)", p.Name, p.Price, p.Category)
  if err != nil {
    return err
  }

  return c.JSON(p)
}

func GetProduct(c *fiber.Ctx) error {
  id := c.Params("id")
  var p Product

  // Retrieve product from database
  err := db.QueryRow("SELECT id, name, price, category FROM products WHERE id = $1", id).Scan(&p.ID, &p.Name, &p.Price, &p.Category)
  if err != nil {
    if err == sql.ErrNoRows {
      return c.Status(fiber.StatusNotFound).SendString("Product not found")
    }
    return err
  }

  return c.JSON(&p)
}

func UpdateProduct(c *fiber.Ctx) error {
  id := c.Params("id")
  p := new(Product)
  if err := c.BodyParser(p); err != nil {
    return err
  }

  // Update product in the database
  _, err := db.Exec("UPDATE products SET name = $1, price = $2, category = $3 WHERE id = $4", p.Name, p.Price, p.Category, id)
  if err != nil {
    return err
  }

  p.ID, _ = strconv.Atoi(id)
  return c.JSON(p)
}

func DeleteProduct(c *fiber.Ctx) error {
  id := c.Params("id")

  // Delete product from database
  _, err := db.Exec("DELETE FROM products WHERE id = $1", id)
  if err != nil {
    return err
  }

  return c.SendStatus(fiber.StatusNoContent)
}

func main() {
  app := fiber.New()
  db = SetupDatabase()
  defer db.Close()

  // Set up routes
  app.Post("/products", CreateProduct)
  app.Get("/products/:id", GetProduct)
  app.Put("/products/:id", UpdateProduct)
  app.Delete("/products/:id", DeleteProduct)

  app.Listen(":3000")
}