#18375: F() doesn't work as expected across multijoin relations
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Reporter: FunkyBob | Owner: akaariai
Type: Bug | Status: new
Component: Database layer | Version: 1.4
(models, ORM) | Resolution:
Severity: Release blocker | Triage Stage: Accepted
Keywords: | Needs documentation: 0
Has patch: 1 | Patch needs improvement: 0
Needs tests: 0 | UI/UX: 0
Easy pickings: 0 |
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Comment (by akaariai):
Hmmh, I think this one is even more complex than I previously thought -
how about
{{{
qs.filter(someval=F('revrel__somecol'), revrel__othercol=F('someval'))
}}}
If the first kwarg is seen first, then we will create a join for revrel.
However, this join is _not_ reusable for the second filter's lookup. If
these are seen in the other order, then we first generate revrel for the
lookup, then reuse it in F().
I know we can fix the above. But I am wondering if we could just weasel
out of this situation: document that use Q() lookups instead if dict
ordering might be a problem. Q() lookups do have a defined order, so there
is no problem in that case.
I have a work in progress patch at:
https://github.com/akaariai/django/compare/ticket_18375
--
Ticket URL: <https://code.djangoproject.com/ticket/18375#comment:10>
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