#26630: Defered constraint checks flush after `post_delete` signal
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Reporter: Alex Madjar | Owner: (none)
Type: Bug | Status: closed
Component: Database layer | Version: dev
(models, ORM) |
Severity: Normal | Resolution: duplicate
Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 1
Easy pickings: 0 | UI/UX: 0
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Changes (by Jacob Walls):
* resolution: => duplicate
* status: assigned => closed
Comment:
I'm also a little unsure. I think the gist of the report is that doing
database queries during a `post_delete` listener is problematic, because
you can query `Choice` rows by `question_id` and get misleading results
(as those rows are in the middle of being cascade deleted).
I'm reading the original report to suggest reordering the `post_delete`
signal to run after constraints are flushed (and all cascade deletes have
happened). I doubt that would be backward compatible.
In #30835 something similar was suggested, and Simon explained you can use
`on_commit()` to defer execution of the callback (to a point when all
cascade deletions have been made). I think I'd suggest rewriting the
signal handler that way to avoid this problem with unstable `Choice`
results.
I'm inclined to close this as duplicate of #30835. As mentioned there, if
there's a proposal for a docs tweak in `post_delete` we could consider it.
(In that case, do reopen #30835!)
Thanks for helping out with triage.
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Ticket URL: <https://code.djangoproject.com/ticket/26630#comment:12>
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