update_or_create() does not persist field changes in save() when performing an update

[Crispin Ali Basah]

It seems when update_or_create() is updating an object, field updates set in the model's overriden save() method is not persisted in the database.

The following simple model illustrates this behavior. field1 is set via the default={...} argument while field2 is an increment of field1 by 1 performed in the model's overridden save() method.

class Test(models.Model):
    field1 = models.PositiveSmallIntegerField(blank=True, null=True)
    field2 = models.PositiveSmallIntegerField(blank=True, null=True)

    def save(self, *args, **kwargs):
        self.field2 = self.field1 + 1
        super().save(*args, **kwargs)

The following call for update_or_create() inserts the object with id 1

>>> (obj, is_created) = Test.objects.update_or_create(id=1, defaults={'field1': 1})
>>> Test.objects.get(id=1).field1
1
>>> Test.objects.get(id=1).field2
2

The following call updates the same object

>>> (obj, is_created) = Test.objects.update_or_create(id=1, defaults={'field1': 10})
>>> Test.objects.get(id=1).field1
10
>>> Test.objects.get(id=1).field2
2

However, field2 does not get updated to 11.

[Crispin Ali Basah]

Duplicate of ticket:34099