如何为实体A设置结构标记可能在GORM中包含B并使make自动创建和预加载

Question

Consider I have BaseNotification and ExtendedNotification structs.

For some notifications they use base_notificaion table only yet some of them will save some extra data into extended_notificaion.

How to setup struct tag in these two structs so that when I run

db.Create(&entendedNotification) // or something else

GORM will know it need to insert a new tuple into extended_notification if needed(for example either it is not nil or fields are filled)

And when I call

db.Preload(`ExtendedNotification`).Find(&notifications)

it will grab all necessary entities accordingly?

Answer 1

If you ensure A's primary key id is a foreign key in B, use like this

type A struct{
    Id int `gorm:"column:id"`
    B []B `gorm:"column:b;ForeignKey:Aid"`
}
type B struct{
    Aid int 
}

if not, I suggest using

func (a *A) AfterFind()error{
    return db.Model(&B{}).Find(&a.B).Error
}