3.0 KiB

Raw Blame History

Database

Connecting to a database

MySQL

NOTE don't forgot params parseTime to handle data type time.Time, more support parameters

import (
    "github.com/jinzhu/gorm"
    _ "github.com/go-sql-driver/mysql"
)
func main() {
  db, err := gorm.Open("mysql", "user:password@/dbname?charset=utf8&parseTime=True&loc=Local")
}

PostgreSQL

import (
    "github.com/jinzhu/gorm"
    _ "github.com/lib/pq"
)
func main() {
  db, err := gorm.Open("postgres", "user=gorm dbname=gorm sslmode=disable")
}

Sqlite3

import (
    "github.com/jinzhu/gorm"
    _ "github.com/mattn/go-sqlite3"
)
func main() {
  db, err := gorm.Open("sqlite3", "/tmp/gorm.db")
}

Write Dialect for unsupported databases

GORM officially support above databases, for unsupported databaes, you could write a dialect for that.

Refer: https://github.com/jinzhu/gorm/blob/master/dialect.go

Generic database object *sql.DB

*sql.DB

// Get generic database object *sql.DB to use its functions
db.DB()

// Connection Pool
db.DB().SetMaxIdleConns(10)
db.DB().SetMaxOpenConns(100)

  // Ping
db.DB().Ping()

Migration

Auto Migration

Automatically migrate your schema, to keep your schema update to date

WARNING AutoMigrate will ONLY create tables, columns and indexes if doesn't exist, WON'T change existing column's type or delete unused columns to protect your data

db.AutoMigrate(&User{})

db.AutoMigrate(&User{}, &Product{}, &Order{})

// Add table suffix when create tables
db.Set("gorm:table_options", "ENGINE=InnoDB").AutoMigrate(&User{})

Has Table

// Check if model `User`'s table has been created or not
db.HasTable(&User{})

// Check table `users` exists or not
db.HasTable("users")

Create Table

db.CreateTable(&User{})

db.Set("gorm:table_options", "ENGINE=InnoDB").CreateTable(&User{})
// will append "ENGINE=InnoDB" to the SQL statement when creating table `users`

Drop table

db.DropTable(&User{})

ModifyColumn

Change column's type

// change column description's data type to `text` for model `User`'s table
db.Model(&User{}).ModifyColumn("description", "text")

DropColumn

db.Model(&User{}).DropColumn("description")

Add Foreign Key

// Add foreign key
// 1st param : foreignkey field
// 2nd param : destination table(id)
// 3rd param : ONDELETE
// 4th param : ONUPDATE
db.Model(&User{}).AddForeignKey("city_id", "cities(id)", "RESTRICT", "RESTRICT")

Indexes

// Add index
db.Model(&User{}).AddIndex("idx_user_name", "name")

// Multiple column index
db.Model(&User{}).AddIndex("idx_user_name_age", "name", "age")

// Add unique index
db.Model(&User{}).AddUniqueIndex("idx_user_name", "name")

// Multiple column unique index
db.Model(&User{}).AddUniqueIndex("idx_user_name_age", "name", "age")

// Remove index
db.Model(&User{}).RemoveIndex("idx_user_name")

3.0 KiB Raw Blame History