#27303: Allow FilterSpecs to return Q-likes
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Reporter: Yeago | Owner: nobody
Type: New feature | Status: new
Component: contrib.admin | Version: 1.10
Severity: Normal | Resolution:
Keywords: filterspec | Triage Stage: Unreviewed
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by Josh Smeaton):
I think I understand the point you're trying to make Steve. Do the docs
here represent the different behaviours you're trying to put across?
https://docs.djangoproject.com/en/1.10/topics/db/queries/#spanning-multi-
valued-relationships
Those docs primarily refer to multi-value relationships which I'm not
certain is the use case you're trying to resolve. But to summarise:
`.filter(multi__value__lookup=1, multi__value__other=2)` is equivalent to
`(MVL=1 AND MVO=2)` because the WHERE clause targets a single join.
{{{
SELECT * FROM model
JOIN multi ON model.multi_id = multi.id
JOIN value on multi.value_id = value.id
WHERE value.MVL=1 AND value.MVO = 2
}}}
Where `.filter(multi__value__lookup=1).filter(multi__value__other=2)` is
logically equivalent to `(MVL=1 OR MVO=2)` because MVL and MVO have
separate joins, so they can both match independently since it's a
multivalue relationship.
{{{
SELECT * FROM model
JOIN multi ON model.multi_id = multi.id
JOIN value on multi.value_id = value.id
JOIN multi m2 ON model.multi_id = m2.id
JOIN value v2 on multi.value_id = v2.id
WHERE value.MVL=1 AND v2.MVO = 2
}}}
Does this correctly summarise the behaviour?
--
Ticket URL: <https://code.djangoproject.com/ticket/27303#comment:13>
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