hernanhrm

// Meal model a record of meals table
type Meal struct {
	ID          uint
	Name        string
	Description string
	DrinkID     uint
	Drink       Drink
}

type Meals []Meal

hernanhrm

type Waitress struct {
	db *sql.DB
}


// getMeals gets 20 meals from the db
func (b Waitress) getMeals() (Meals, error) {
	// this method has the logic to query from the db, if you want to see
	// the actual code, you can go the repo

hernanhrm

func (b Waitress) ListMenu() (Meals, error) {
	// the `1` of our `N+1`
	meals, err := b.getMeals()
	if err != nil {
		return nil, err
	}

	// here is our waitress going back and forth 
	// from floor 1 to 10, this will be the `N` of our `N+1`
	for i, meal := range meals {

hernanhrm

SELECT m.id, m.name, m.description, d.name, d.description
FROM meals AS m
	INNER JOIN drinks AS d ON d.id = m.drink_id

hernanhrm

type Solution1 struct {
	db *sql.DB
}

func (s Solution1) ListMenu() (Meals, error) {
	// this method will execute the previous SQL
	// SELECT
	// m.id,
	// 	m.name,
	// 	m.description,

hernanhrm

func (s Solution2) ListMenu() (Meals, error) {
	meals, err := s.getMeals()
	if err != nil {
		return nil, err
	}

	// this is our waitress bringing everything in a bussing cart 
	drinks, err := s.getDrinksByIDsIn(meals.GetUniqueDrinkIDs())
	if err != nil {

hernanhrm

// to query the drinks, we need to know their IDs, for that
// we add this method to our `Meals` slice
func (m Meals) GetUniqueDrinkIDs() []uint {
	var ids []uint
	drinks := make(map[uint]struct{}, 0)

	for _, v := range m {
		_, ok := drinks[v.DrinkID]
		if ok {
			continue

hernanhrm

CREATE TABLE users
(
    id         SERIAL       NOT NULL,
    first_name VARCHAR(100) NOT NULL,
    last_name  VARCHAR(100),
    email      VARCHAR(100) NOT NULL,
    password   VARCHAR(256) NOT NULL
);

hernanhrm

func init() {
	goose.AddMigration(upCreateUsersTable, downCreateUsersTable)
}

func upCreateUsersTable(tx *sql.Tx) error {
	_, err := tx.Exec(`
		CREATE TABLE users
		(
			id         SERIAL       NOT NULL,
			first_name VARCHAR(100) NOT NULL,

hernanhrm

// PaymentMethodStrategy will let us interchange 
// the payment method in the context
type PaymentMethodStrategy interface {
		Pay() error
}