Composite Primary Key

Set multiple fields as primary key to enable composite primary key

type Product struct {
  ID           string `gorm:"primary_key"`
  LanguageCode string `gorm:"primary_key"`
  Code         string
  Name         string
}

Note that integer fields with primary_key tag are auto_increment by default. That can result in multiple auto-incremented integer primary keys instead of a single composite primary key.

To create the composite primary key containing ints you need to turn off auto_increment for the int fields:

type Product struct {
  CategoryID uint64 `gorm:"primary_key;auto_increment:false"`
  TypeID     uint64 `gorm:"primary_key;auto_increment:false"`
}