Using a custom DbAuthoring model I add fields createdBy to my database models. This works fine (I have to populate them manually fetching the user ID out of the JWT claim though).

Of course, the IDs in these fields refer to the user table. But I want to treat them as strings for most cases, so I don’t have a “strong” relation set up. But I tried to add a custom relation:

This looks like:

// I am using a custom metadata model instead of gorm.model as I use UUID of type string as ID
type DbMetaData struct {
    CreatedAt time.Time `json:"createdAt"`
    UpdatedAt time.Time `json:"updatedAt"`
    DeletedAt gorm.DeletedAt `gorm:"index" json:"-"`
}

type DbAuthorData struct {
    CreatedBy string `json:"createdBy"`
    CreatedByUser *DbUser `gorm:"foreignKey:CreatedBy"` // I need to use a pointer here, as I do not want this field to be filled out by default, and I will get invalid "Invalid recursive type 'DbUser' DbUser → DbAuthorData → DbUser", as DbUser does have the same fields
}

type MyModel struct {
    DbAuthorData
    DbMetaData
    ID              string `gorm:"primaryKey"`
}

The foreign key is created correctly.

How do I select the data with a filled CreatedBy correctly?

This works as expected, created_by is filled, CreatedByUser is nil:

var myModels []MyModel
db.Find(&myModels)

How to I join and query these tables with GORM, so that CreatedByUser is filled with data? Is this even possible automatically?

Preload does not work (invalid relation), as I am using a pointer, Joining or using a custom query is returning the correct data, but not filling CreatedByUser.