#33984: Related managers cache gets stale after saving a fetched model with new
PK
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Reporter: joeli | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 4.1
(models, ORM) |
Severity: Release blocker | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by joeli):
Replying to [comment:3 Bhuvnesh]:
> I am a bit confuse here, Using clone method all the tags are being
copied from the old instance still the actual tags for the new instance (
new_thing ) are empty after fetching the new instance again? why the tags
of old instance are not cloned ?
That is the bug here: in `.clone()` after doing `self.pk = None` and
`self.save()` to create a new copy, `self.tags` still points to the old
thing's related manager. So `.clone()` ends up setting the tags for the
old instance (that already has said tags). Then it returns a thing that
pretends to be the `new_thing` but actually returns the tags of the old
thing unless you completely refetch it from database.
--
Ticket URL: <https://code.djangoproject.com/ticket/33984#comment:4>
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