Settings

GORM provides Set, Get, InstanceSet, InstanceGet methods allow users pass values to hooks or other methods

GORM uses this for some features, like pass creating table options when migrating table.

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

Set / Get

Use Set / Get pass settings to hooks methods, for example:

type User struct {
  gorm.Model
  CreditCard CreditCard
  // ...
}

func (u *User) BeforeCreate(tx *gorm.DB) error {
  myValue, ok := tx.Get("my_value")
  // ok => true
  // myValue => 123
}

type CreditCard struct {
  gorm.Model
  // ...
}

func (card *CreditCard) BeforeCreate(tx *gorm.DB) error {
  myValue, ok := tx.Get("my_value")
  // ok => true
  // myValue => 123
}

myValue := 123
db.Set("my_value", myValue).Create(&User{})

InstanceSet / InstanceGet

Use InstanceSet / InstanceGet pass settings to current *Statement‘s hooks methods, for example:

type User struct {
  gorm.Model
  CreditCard CreditCard
  // ...
}

func (u *User) BeforeCreate(tx *gorm.DB) error {
  myValue, ok := tx.InstanceGet("my_value")
  // ok => true
  // myValue => 123
}

type CreditCard struct {
  gorm.Model
  // ...
}

// When creating associations, GORM creates a new `*Statement`, so can't read other instance's settings
func (card *CreditCard) BeforeCreate(tx *gorm.DB) error {
  myValue, ok := tx.InstanceGet("my_value")
  // ok => false
  // myValue => nil
}

myValue := 123
db.InstanceSet("my_value", myValue).Create(&User{})