Gorm how to know Upsert is insert or update

maybe i can Register Callback???

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Comment From: keemyb

I've not used Upsert, but say you have the model:

type Foo struct {
  gorm.Model

  FooID string
  OtherField string
}

You can achieve this by first doing an update with a where condition, then checking to see if the update affected anything. If it didn't you know you will have to insert a record:

func upsert(db *gorm.DB, foo *Foo) (wasUpdate bool, err error) {
    updates := db.Model(foo).
        Where("foo_id = ?", foo.FooID).
        Updates(foo)
    if updates.RowsAffected == 0 {
        err = db.Create(foo).Error
        if err != nil {
            return
        }
    } else {
                wasUpdate = true
        }
        return
}

Comment From: github-actions[bot]

Comment From: dandyhuang

I've not used Upsert, but say you have the model:

``` type Foo struct { gorm.Model

FooID string OtherField string } ```

You can achieve this by first doing an update with a where condition, then checking to see if the update affected anything. If it didn't you know you will have to insert a record:

func upsert(db *gorm.DB, foo *Foo) (wasUpdate bool, err error) { updates := db.Model(foo). Where("foo_id = ?", foo.FooID). Updates(foo) if updates.RowsAffected == 0 { err = db.Create(foo).Error if err != nil { return } } else { wasUpdate = true } return }

Of course this can be achieved, but you must lock the table like for update to ensure atomic。 I test upsert, when db.RowsAffected = 1 is insert,db.RowsAffected = 2 is update。 But I am not sure if it is correct