GetAll Retrieve user list with eager loading credit cards.

CreditCard belongs to UserModel, UserID is the foreign key.

User belongs to Company, CompanyID is the foreign key.

User2 has and belongs to many languages, `user_languages` is the join table When using GORM AutoMigrate to create a table for User, GORM will create the join table automatically.

UserM has many CreditCards, UserID is the foreign key.

UserModel has one CreditCard, UserID is the foreign key.

UserModelOverrideForeignKey For a has one relationship, a foreign key field must also exist, the owner will save the primary key of the model belongs to it into this field.

UserModelOverrideReferences When save User model, save User.name to CreditCard.UserName as to set up the foreign key.

UserSpecifyReference GORM usually guess the relationship as `has one` if override foreign key name already exists in owner's type, we need to specify references in the belongs to relationship.