gorm学习总结(四)

58.一对一

type User struct {
  gorm.Model
  Profile   Profile
  ProfileID int
}

type Profile struct {
  gorm.Model
  Name string
}

db.Model(&user).Related(&profile)
// SELECT * FROM profiles WHERE id = 111; // 111是user的外键ProfileID

 

61.一对多

// User 包含多个 emails, UserID 为外键
type User struct {
    gorm.Model
    Emails   []Email
}

type Email struct {
    gorm.Model
    Email   string
    UserID  uint
}

db.Model(&user).Related(&emails)
 SELECT * FROM emails WHERE user_id = 111; // 111 是 user 的主键

62.多对多

// User 包含并属于多个 languages, 使用 `user_languages` 表连接
type User struct {
    gorm.Model
    Languages         []Language `gorm:"many2many:user_languages;"`
}

type Language struct {
    gorm.Model
    Name string
}

db.Model(&user).Related(&languages, "Languages")
 SELECT * FROM "languages" INNER JOIN "user_languages" ON "user_languages"."language_id" = "languages"."id" WHERE "user_languages"."user_id" = 111