GORM CheatSheet

Import

import (
  "gorm.io/driver/mysql"
  "gorm.io/driver/postgres"
  "gorm.io/gorm"
)

func main() {
  // MYSQL:
  // refer https://github.com/go-sql-driver/mysql#dsn-data-source-name for details
  dsn := "user:pass@tcp(127.0.0.1:3306)/dbname?charset=utf8mb4&parseTime=True&loc=Local"
  db, err := gorm.Open(mysql.Open(dsn), &gorm.Config{})

  // PostgreSQL:
  dsn := "host=localhost user=gorm password=gorm dbname=gorm port=9920 sslmode=disable TimeZone=Asia/Shanghai"
  db, err := gorm.Open(postgres.Open(dsn), &gorm.Config{})

  // SQLite:
  db, err := gorm.Open(sqlite.Open("gorm.db"), &gorm.Config{})

  // SQL Server:
  dsn := "sqlserver://gorm:LoremIpsum86@localhost:9930?database=gorm"
  db, err := gorm.Open(sqlserver.Open(dsn), &gorm.Config{})

  // Connection Pool:
  sqlDB, err := db.DB()
  // SetMaxIdleConns sets the maximum number of connections in the idle connection pool.
  sqlDB.SetMaxIdleConns(10)
  // SetMaxOpenConns sets the maximum number of open connections to the database.
  sqlDB.SetMaxOpenConns(100)  
  // SetConnMaxLifetime sets the maximum amount of time a connection may be reused.
  sqlDB.SetConnMaxLifetime(time.Hour)

}

• To handle time.Time correcxtly, include the parseTime as a parameter

CRUD

// Create Single:
user := User{Name: "John", Age: 18, Birthday: time.Now()}

result := db.Create(&user) // pass pointer of data to Create
user.ID                    // returns inserted data's primary key
result.Error               // returns error
result.RowsAffected        // returns inserted records count

// Create Multiple:
users := []*User{
  {Name: "Jinzhu", Age: 18, Birthday: time.Now()},
  {Name: "Jackson", Age: 19, Birthday: time.Now()},
}

result := db.Create(users) // pass a slice to insert multiple row
result.Error               // returns error
result.RowsAffected        // returns inserted records count