#33608: Wrong sql generation for FK with db_constraint=False causing results to
incorrectly get dropped from a queryset
-------------------------------------+-------------------------------------
Reporter: Mathieu | Owner: nobody
Hinderyckx |
Type: Bug | Status: new
Component: Database | Version: 4.0
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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When using a FK which has db_constraint=False, the sql generated when
using the combination of a filter() and select_related() are wrong,
causing results which should be included in a queryset to not be.
The problem occurs when the remote object does not exist in the table
where the FK points to. In some cases the ORM will generate an `INNER
JOIN` statement instead of a `LEFT OUTER JOIN` causing a row to be wrongly
omitted.
I have made a POC setup for this behaviour on
https://github.com/mhindery/django_fk_issue, with testcases containing
some working lookups, and one specific method that demonstrate the
behaviour. I've included in comments in the tests the query which gets
generated, showing the problematic join.
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Ticket URL: <https://code.djangoproject.com/ticket/33608>
Django <https://code.djangoproject.com/>
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