#33312: Errors when trying to clone an object from a deferred queryset
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Reporter: Adam | Owner: nobody
Sołtysik |
Type: Bug | Status: new
Component: Database | Version: 3.2
layer (models, ORM) |
Severity: Normal | Keywords:
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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As per [https://docs.djangoproject.com/en/3.2/topics/db/queries/#copying-
model-instances documentation], it's possible to clone objects by setting
`pk = None`.
However, if the object to clone comes from a deferred queryset (after
calling `defer` or `only`), trying to save the copy raises some hard to
decipher exceptions.
{{{
class DeferCloneTest(TestCase):
@classmethod
def setUpTestData(cls):
SimpleItem.objects.create(name="test", value=42)
def _get_item(self):
item = SimpleItem.objects.defer('value').first() # same with
`only` instead of `defer`
item.pk = None
item._state.adding = True # doesn't seem to change anything
return item
def test_save(self):
self._get_item().save() # ValueError: Cannot force an update in
save() with no primary key.
def test_save_force_insert(self):
self._get_item().save(force_insert=True) #
SimpleItem.DoesNotExist
def test_bulk_create(self):
SimpleItem.objects.bulk_create([self._get_item()]) #
SimpleItem.DoesNotExist
}}}
Possibly related: #27419, #28019.
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Ticket URL: <https://code.djangoproject.com/ticket/33312>
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