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Many To Many

Many To Many 会在两个模型之间建立一个连接表。

例如，User 和 Language，一个 User 可以说多种 Language，一种 Language 也可以被多个 User 使用。

type User struct {
  gorm.Model
  Languages []Language `gorm:"many2many:user_languages;"`
}

type Language struct {
  gorm.Model
  Name string
}

当使用 AutoMigrate 为 User 创建表时，GORM 会自动创建连接表 user_languages。

反向引用​

type User struct {
  gorm.Model
  Languages []Language `gorm:"many2many:user_languages;"`
}

type Language struct {
  gorm.Model
  Name string
  Users []User `gorm:"many2many:user_languages;"`
}

重写外键​

type User struct {
  gorm.Model
  Languages []Language `gorm:"many2many:user_languages;foreignKey:Refer;joinForeignKey:UserRefer;References:ID;joinReferences:LanguageID"`
}

type Language struct {
  gorm.Model
  Name string
}