Gorm Wrong foreignKey setup for multiple embedded belongs-to relations of same type

GORM Playground Link

https://github.com/go-gorm/playground/pull/672

Description

cnp from the playground PR

When using multiple embedded belongs-to relations only 1 database foreignKey is created. Expected: a foreignKey for each relation is created.

type Country struct {
    Name string `gorm:"primaryKey"`
}

type Address struct {
    CountryName string
    Country     Country
}

type Org struct {
    ID       int
    Address1 Address `gorm:"embedded;embeddedPrefix:address1_"`
    Address2 Address `gorm:"embedded;embeddedPrefix:address2_"`
}

In the above example there should be a foreignKey for address1 -> countries and a foreignKey address2 -> countries. gorm only creates one foreignKey fk_orgs_country => address2_country_name->countries

Hint: * the generated naming for the foreignKey should respect the fieldName with its path / parent struct, as both relations result in the same foreignKey name. * the relations are correctly detected as embedded and belongs-to, but result in only one entry in the relations map, this is due to the fact that only fieldName is used within this map * possible solution: consider using BindNames of the field for name generation

Comment From: a631807682

Embedded is not used to define the relationship between data tables. In this example, only Address and Country have relationships. https://gorm.io/docs/preload.html#Embedded-Preloading

Comment From: staust

Embedded is not used to define the relationship between data tables. In this example, only Address and Country have relationships. https://gorm.io/docs/preload.html#Embedded-Preloading

Is it technically not possible or currently just not supported? I do not 100% get it but then it is not possible to have a proper go struct reflecting the above relation. Defining two times the same struct (Address) with different names would then work but result in dirty go code.

Do you have a suggestion how you could achieve such an relation with a proper model?

Comment From: a631807682

Embedded is not used to define the relationship between data tables. In this example, only Address and Country have relationships. gorm.io/docs/preload.html#Embedded-Preloading

Is it technically not possible or currently just not supported? I do not 100% get it but then it is not possible to have a proper go struct reflecting the above relation. Defining two times the same struct (Address) with different names would then work but result in dirty go code.

Do you have a suggestion how you could achieve such an relation with a proper model?

It is not currently supported. One possible way is to define embedded and relationship at the same time, which may need to support more tags.

Comment From: staust

I guess this then also applies for https://github.com/go-gorm/gorm/issues/6750 as this is somehow related. Currently this makes things even worse as the association saving mode will always break the relation in the above example. I did some further investigation with a similar struct where you need to explicitly exclude the "country" from the parent struct "address" from saving.

I hope this gives a bit more context.