Is it possible to define a callback for all structs? about gorm HOT 5 CLOSED

Hi @leebrooks0

No, this is not supported, but under consideration.

But even if gorm supported it, how will you use it for created_by_user_id?

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I intend using Revel, which has cookie based sessions, so once the user has logged in I would save their user id in the session and then fetch it when needed.

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But because you can't pass any argument to callbacks, so how to get the user id from session?

So maybe better if gorm support setters/getters like this, any suggestions?

// model
type User struct {
    UpdatedBy string
}

// define callbacks
func SaveUpdatedBy(tx *gorm.DB, obj interface{}) (err error) {
    updated_by := reflect.ValueOf(obj).Elem().FieldByName("UpdatedBy")
    if updated_by.IsValid() {
        updated_by.Set(reflect.ValueOf(tx.Get("current_user_id")))
    }
    return
}

DB.RegisterCallback("BeforeSave", SaveUpdatedBy)

// controller
db := DB.Set("current_user_id", 20) // 20 is the value from session
db.Save(&user)

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I see, so User.UpdatedBy needs to be manually set. It seems like these things just need to be handled on a case by case basis. If User.UpdatedBy was "Fred" and then "John" makes the update, then unless you manually reset User.UpdatedBy to "John" then on save it is still going to say "Fred" made the update.

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I am planing a plugin system for gorm, hope this could resolve your problem, will notice you when it is done.

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