Commit ba015e0a authored by Malcolm Tredinnick's avatar Malcolm Tredinnick
Browse files

Fixed #7181 -- when ordering by a potentially NULL field, use a left-outer join 

so that the ordering doesn't accidentally restrict the result set.

(Ironically, one existing test actually showed this problem, but I was too
dumb to notice the result was incorrect.)


git-svn-id: http://code.djangoproject.com/svn/django/trunk@7761 bcc190cf-cafb-0310-a4f2-bffc1f526a37
parent e41df5ad

django/db/models/sql/query.py

+4 −0
Original line number Diff line number Diff line
@@ -610,6 +610,10 @@ class Query(object): 
        alias = joins[-1]

        col = target.column



        # Must use left outer joins for nullable fields.

        for join in joins:

            self.promote_alias(join)



        # If we get to this point and the field is a relation to another model,

        # append the default ordering for that model.

        if field.rel and len(joins) > 1 and opts.ordering:

tests/regressiontests/queries/models.py

+7 −1
Original line number Diff line number Diff line
@@ -499,7 +499,7 @@ FieldError: Infinite loop caused by ordering. 
# Ordering by a many-valued attribute (e.g. a many-to-many or reverse

# ForeignKey) is legal, but the results might not make sense. That isn't

# Django's problem. Garbage in, garbage out.

>>> Item.objects.all().order_by('tags', 'id')

>>> Item.objects.filter(tags__isnull=False).order_by('tags', 'id')

[<Item: one>, <Item: two>, <Item: one>, <Item: two>, <Item: four>]



# If we replace the default ordering, Django adjusts the required tables
@@ -762,5 +762,11 @@ Bug #7076 -- excluding shouldn't eliminate NULL entries. 
>>> Tag.objects.exclude(parent__name=t1.name)

[<Tag: t1>, <Tag: t4>, <Tag: t5>]



Bug #7181 -- ordering by related tables should accomodate nullable fields (this

test is a little tricky, since NULL ordering is database dependent. Instead, we

just count the number of results).

>>> len(Tag.objects.order_by('parent__name'))

5



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