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Code Issues 32 Releases Wiki Activity

queryset-refactor: Fixed exclude() filtering for the various N-to-many relations.

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This means we can now do nested SQL queries (since we need nested queries to
get the right answer). It requires poking directly at the Query class. Might
add support for this through QuerySets later.


git-svn-id: http://code.djangoproject.com/svn/django/branches/queryset-refactor@7170 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Malcolm Tredinnick
2008-02-28 12:57:10 +00:00
parent 0588dee34c
commit 33a0862215
5 changed files with 119 additions and 27 deletions
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19
tests/regressiontests/queries/models.py
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@@ -322,22 +322,19 @@ Bug #5324
>>> Author.objects.exclude(item__name='one').distinct().order_by('name')
[<Author: a2>, <Author: a3>, <Author: a4>]
# Excluding across a m2m relation when there is more than one related object
# associated was problematic.
>>> Item.objects.exclude(tags__name='t1').order_by('name')
[<Item: four>, <Item: three>]
>>> Item.objects.exclude(tags__name='t1').exclude(tags__name='t4')
[<Item: three>]
# Excluding from a relation that cannot be NULL should not use outer joins.
>>> query = Item.objects.exclude(creator__in=[a1, a2]).query
>>> query.LOUTER not in [x[2][2] for x in query.alias_map.values()]
True
# When only one of the joins is nullable (here, the Author -> Item join), we
# should only get outer joins after that point (one, in this case). We also
# show that three tables (so, two joins) are involved.
>>> qs = Report.objects.exclude(creator__item__name='one')
>>> list(qs)
[<Report: r2>]
>>> len([x[2][2] for x in qs.query.alias_map.values() if x[2][2] == query.LOUTER])
1
>>> len(qs.query.alias_map)
3
Similarly, when one of the joins cannot possibly, ever, involve NULL values (Author -> ExtraInfo, in the following), it should never be promoted to a left outer join. So hte following query should only involve one "left outer" join (Author -> Item is 0-to-many).
>>> qs = Author.objects.filter(id=a1.id).filter(Q(extra__note=n1)|Q(item__note=n3))
>>> len([x[2][2] for x in qs.query.alias_map.values() if x[2][2] == query.LOUTER])