Golang Gorm's relationship implementation example

// `User` belongs to `Profile`, `ProfileID` is a foreign keytype User struct {
  
  Profile   Profile
  ProfileID int
}
type Profile struct {
  
  Name string
}
(&user).Related(&profile)
///// SELECT * FROM profiles WHERE id = 111; // 111 is the foreign key ProfileID of user

type Profile struct {
    
    Name string
}
type User struct {
    
    Profile      Profile `gorm:"ForeignKey:ProfileRefer"` // Use ProfileRefer as a foreign key    ProfileRefer int
}

type Profile struct {
    
    Refer string
    Name  string
}
type User struct {
    
    Profile   Profile `gorm:"ForeignKey:ProfileID;AssociationForeignKey:Refer"`
    ProfileID int
}

// User contains a CreditCard, UserID is a foreign keytype User struct {
    
    CreditCard   CreditCard
}
type CreditCard struct {
    
    UserID   uint
    Number   string
}
var card CreditCard
(&user).Related(&card, "CreditCard")
//// SELECT * FROM credit_cards WHERE user_id = 123; // 123 is user's primary key
// CreditCard is the field name of user, which means getting the CreditCard relationship of user and populating it into the variable// If the field name is the same as the type name of the variable, as shown in the above example, it can be omitted, such as:(&user).Related(&card)

type Profile struct {
  
  Name      string
  UserRefer uint
}
type User struct {
  
  Profile Profile `gorm:"ForeignKey:UserRefer"`
}

type Profile struct {
  
  Name   string
  UserID uint
}
type User struct {
  
  Refer   string
  Profile Profile `gorm:"ForeignKey:UserID;AssociationForeignKey:Refer"`
}

// User contains multiple emails, UserID is a foreign keytype User struct {
    
    Emails   []Email
}
type Email struct {
    
    Email   string
    UserID  uint
}
(&user).Related(&emails)
///// SELECT * FROM emails WHERE user_id = 111; // 111 is the primary key of user

type Profile struct {
  
  Name      string
  UserRefer uint
}
type User struct {
  
  Profiles []Profile `gorm:"ForeignKey:UserRefer"`
}

type Profile struct {
  
  Name   string
  UserID uint
}
type User struct {
  
  Refer   string
  Profiles []Profile `gorm:"ForeignKey:UserID;AssociationForeignKey:Refer"`
}

// User contains and belongs to multiple languages, join using the `user_languages` tabletype User struct {
    
    Languages         []Language `gorm:"many2many:user_languages;"`
}
type Language struct {
    
    Name string
}
(&user).Related(&languages, "Languages")
//// SELECT * FROM "languages" INNER JOIN "user_languages" ON "user_languages"."language_id" = "languages"."id" WHERE "user_languages"."user_id" = 111

type CustomizePerson struct {
  IdPerson string             `gorm:"primary_key:true"`
  Accounts []CustomizeAccount `gorm:"many2many:PersonAccount;ForeignKey:IdPerson;AssociationForeignKey:IdAccount"`
}
type CustomizeAccount struct {
  IdAccount string `gorm:"primary_key:true"`
  Name      string
}

type Cat struct {
    Id    int
    Name  string
    Toy   Toy `gorm:"polymorphic:Owner;"`
  }
  type Dog struct {
    Id   int
    Name string
    Toy  Toy `gorm:"polymorphic:Owner;"`
  }
  type Toy struct {
    Id        int
    Name      string
    OwnerId   int
    OwnerType string
  }

// Start the association modevar user User
(&user).Association("Languages")
// `user` is the source, it needs to be a valid record (including the primary key)// `Languages` is the field name of the source in the relationship.// If these conditions do not match, an error will be returned, check it:// (&user).Association("Languages").Error
// Query - Find all related relationships(&user).Association("Languages").Find(&languages)
// Append - Adding a new many2many, has_many association will replace the current has_one, belongs_to association(&user).Association("Languages").Append([]Language{languageZH, languageEN})
(&user).Association("Languages").Append(Language{Name: "DE"})
// Delete - Delete the relationship between the source and passed parameters, and will not delete these parameters(&user).Association("Languages").Delete([]Language{languageZH, languageEN})
(&user).Association("Languages").Delete(languageZH, languageEN)
// Replace - Replace the current association with new association(&user).Association("Languages").Replace([]Language{languageZH, languageEN})
(&user).Association("Languages").Replace(Language{Name: "DE"}, languageEN)
// Count - Returns the current associated count(&user).Association("Languages").Count()
// Clear - Delete the relationship between the source and the current association, and will not delete these associations(&user).Association("Languages").Clear()