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Variables Globales en Golang, si o no?
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package db | |
import "github.com/go-pg/pg/v10" | |
var db *pg.DB // Nuestra variable global, la cual probablemente inicializamos en el mail.go | |
type Customer struct { | |
ID int | |
Name string | |
LastName string | |
} | |
func SaveCustomer(cust Customer) error { | |
// Al ejecutar nuestro test si no satisfacemos `db` esto va a fallar por un nil pointer | |
_, err := db.Exec("insert into customers (id, name, lastname) values (%d, %s, %s)", cust.ID, cust.Name, cust.LastName) | |
if err != nil { | |
return err | |
} | |
return nil | |
} | |
// Un aproach es crear una estructura y poder inyectar la dependencia por constructor | |
type CustomerRepository struct { | |
db *pg.DB | |
} | |
// NewCustomerRepository crea un repositorio y le inyecta | |
// la DB, por lo que en nuestro test | |
// si siempre usamos el constructor | |
// lograremos satisfacer esa dependecia | |
func NewCustomerRepository(db *pg.DB) CustomerRepository { | |
return CustomerRepository{ | |
db: db, | |
} | |
} | |
func (repo CustomerRepository) SaveCustomer(cust Customer) error { | |
// Al ejecutar nuestro test si no satisfacemos `db` esto va a fallar por un nil pointer | |
_, err := repo.db.Exec("insert into customers (id, name, lastname) values (%d, %s, %s)", cust.ID, cust.Name, cust.LastName) | |
if err != nil { | |
return err | |
} | |
return nil | |
} |
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package db | |
import "github.com/go-pg/pg/v10" | |
var db *pg.DB | |
func GetDB() *pg.DB { | |
if db == nil { | |
db = pg.Connect(&pg.Options{ | |
Addr: "localhost:5432", | |
User: "postgres", | |
Password: "password", | |
Database: "testdb", | |
}) | |
// outside we need defer db.Close() | |
} | |
return db | |
} |
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package main | |
import "postgres/db" | |
func main() { | |
connection := db.GetDB() // Si es nula, se inicializa la DB | |
_, err := connection.Exec("insert into customers(...) values (...)") | |
if err != nil { | |
panic(err.Error()) | |
} | |
// ... | |
connection := db.GetDB() // Es la misma conexión que arriba. | |
_, err := connection.Exec("insert into products(...) values (...)") | |
if err != nil { | |
panic(err.Error()) | |
} | |
} |
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