Fixed #20564 -- Generic relations exclude() regression

The patch for #19385 caused a regression in certain generic relations
.exclude() filters if a subquery was needed. The fix contains a
refactoring to how Query.split_exclude() and Query.trim_start()
interact.

Thanks to Trac alias nferrari for the report.
This commit is contained in:
Anssi Kääriäinen 2013-06-06 00:29:44 +03:00
parent 8c5b805ca1
commit 31fd64ad8a
3 changed files with 138 additions and 51 deletions

View File

@ -1422,7 +1422,9 @@ class Query(object):
query.clear_ordering(True)
# Try to have as simple as possible subquery -> trim leading joins from
# the subquery.
trimmed_joins = query.trim_start(names_with_path)
trimmed_prefix, contains_louter = query.trim_start(names_with_path)
query.remove_inherited_models()
# Add extra check to make sure the selected field will not be null
# since we are adding a IN <subquery> clause. This prevents the
# database from tripping over IN (...,NULL,...) selects and returning
@ -1431,38 +1433,20 @@ class Query(object):
alias, col = query.select[0].col
query.where.add((Constraint(alias, col, query.select[0].field), 'isnull', False), AND)
# Still make sure that the trimmed parts in the inner query and
# trimmed prefix are in sync. So, use the trimmed_joins to make sure
# as many path elements are in the prefix as there were trimmed joins.
# In addition, convert the path elements back to names so that
# add_filter() can handle them.
trimmed_prefix = []
paths_in_prefix = trimmed_joins
for name, path in names_with_path:
if paths_in_prefix - len(path) < 0:
break
trimmed_prefix.append(name)
paths_in_prefix -= len(path)
join_field = path[paths_in_prefix].join_field
# TODO: This should be made properly multicolumn
# join aware. It is likely better to not use build_filter
# at all, instead construct joins up to the correct point,
# then construct the needed equality constraint manually,
# or maybe using SubqueryConstraint would work, too.
# The foreign_related_fields attribute is right here, we
# don't ever split joins for direct case.
trimmed_prefix.append(
join_field.field.foreign_related_fields[0].name)
trimmed_prefix = LOOKUP_SEP.join(trimmed_prefix)
condition = self.build_filter(
('%s__in' % trimmed_prefix, query),
current_negated=True, branch_negated=True, can_reuse=can_reuse)
# Intentionally leave the other alias as blank, if the condition
# refers it, things will break here.
extra_restriction = join_field.get_extra_restriction(
self.where_class, None, [t for t in query.tables if query.alias_refcount[t]][0])
if extra_restriction:
query.where.add(extra_restriction, 'AND')
if contains_louter:
or_null_condition = self.build_filter(
('%s__isnull' % trimmed_prefix, True),
current_negated=True, branch_negated=True, can_reuse=can_reuse)
condition.add(or_null_condition, OR)
# Note that the end result will be:
# (outercol NOT IN innerq AND outercol IS NOT NULL) OR outercol IS NULL.
# This might look crazy but due to how IN works, this seems to be
# correct. If the IS NOT NULL check is removed then outercol NOT
# IN will return UNKNOWN. If the IS NULL check is removed, then if
# outercol IS NULL we will not match the row.
return condition
def set_empty(self):
@ -1821,35 +1805,58 @@ class Query(object):
def trim_start(self, names_with_path):
"""
Trims joins from the start of the join path. The candidates for trim
are the PathInfos in names_with_path structure. Outer joins are not
eligible for removal. Also sets the select column so the start
matches the join.
are the PathInfos in names_with_path structure that are m2m joins.
This method is mostly useful for generating the subquery joins & col
in "WHERE somecol IN (subquery)". This construct is needed by
split_exclude().
Also sets the select column so the start matches the join.
This method is meant to be used for generating the subquery joins &
cols in split_exclude().
Returns a lookup usable for doing outerq.filter(lookup=self). Returns
also if the joins in the prefix contain a LEFT OUTER join.
_"""
all_paths = []
for _, paths in names_with_path:
all_paths.extend(paths)
direct_join = True
contains_louter = False
for pos, path in enumerate(all_paths):
if self.alias_map[self.tables[pos + 1]].join_type == self.LOUTER:
direct_join = False
pos -= 1
if path.m2m:
break
if self.alias_map[self.tables[pos + 1]].join_type == self.LOUTER:
contains_louter = True
self.unref_alias(self.tables[pos])
if path.direct:
direct_join = not direct_join
join_side = 0 if direct_join else 1
# The path.join_field is a Rel, lets get the other side's field
join_field = path.join_field.field
# Build the filter prefix.
trimmed_prefix = []
paths_in_prefix = pos
for name, path in names_with_path:
if paths_in_prefix - len(path) < 0:
break
trimmed_prefix.append(name)
paths_in_prefix -= len(path)
trimmed_prefix.append(
join_field.foreign_related_fields[0].name)
trimmed_prefix = LOOKUP_SEP.join(trimmed_prefix)
# Lets still see if we can trim the first join from the inner query
# (that is, self). We can't do this for LEFT JOINs because we would
# miss those rows that have nothing on the outer side.
if self.alias_map[self.tables[pos + 1]].join_type != self.LOUTER:
select_fields = [r[0] for r in join_field.related_fields]
select_alias = self.tables[pos + 1]
join_field = path.join_field
if hasattr(join_field, 'field'):
join_field = join_field.field
select_fields = [r[join_side] for r in join_field.related_fields]
self.unref_alias(self.tables[pos])
extra_restriction = join_field.get_extra_restriction(
self.where_class, None, self.tables[pos + 1])
if extra_restriction:
self.where.add(extra_restriction, AND)
else:
# TODO: It might be possible to trim more joins from the start of the
# inner query if it happens to have a longer join chain containing the
# values in select_fields. Lets punt this one for now.
select_fields = [r[1] for r in join_field.related_fields]
select_alias = self.tables[pos]
self.select = [SelectInfo((select_alias, f.column), f) for f in select_fields]
self.remove_inherited_models()
return pos
return trimmed_prefix, contains_louter
def is_nullable(self, field):
"""

View File

@ -131,3 +131,27 @@ class HasLinks(models.Model):
class HasLinkThing(HasLinks):
pass
class A(models.Model):
flag = models.NullBooleanField()
content_type = models.ForeignKey(ContentType)
object_id = models.PositiveIntegerField()
content_object = generic.GenericForeignKey('content_type', 'object_id')
class B(models.Model):
a = generic.GenericRelation(A)
class Meta:
ordering = ('id',)
class C(models.Model):
b = models.ForeignKey(B)
class Meta:
ordering = ('id',)
class D(models.Model):
b = models.ForeignKey(B, null=True)
class Meta:
ordering = ('id',)

View File

@ -5,7 +5,7 @@ from django.test import TestCase, skipIfDBFeature
from .models import (
Address, Place, Restaurant, Link, CharLink, TextLink,
Person, Contact, Note, Organization, OddRelation1, OddRelation2, Company,
Developer, Team, Guild, Tag, Board, HasLinkThing)
Developer, Team, Guild, Tag, Board, HasLinkThing, A, B, C, D)
class GenericRelationTests(TestCase):
@ -156,3 +156,59 @@ class GenericRelationTests(TestCase):
self.assertQuerysetEqual(
HasLinkThing.objects.exclude(links=l1),
[hs2], lambda x: x)
def test_ticket_20564(self):
b1 = B.objects.create()
b2 = B.objects.create()
b3 = B.objects.create()
c1 = C.objects.create(b=b1)
c2 = C.objects.create(b=b2)
c3 = C.objects.create(b=b3)
A.objects.create(flag=None, content_object=b1)
A.objects.create(flag=True, content_object=b2)
self.assertQuerysetEqual(
C.objects.filter(b__a__flag=None),
[c1, c3], lambda x: x
)
self.assertQuerysetEqual(
C.objects.exclude(b__a__flag=None),
[c2], lambda x: x
)
def test_ticket_20564_nullable_fk(self):
b1 = B.objects.create()
b2 = B.objects.create()
b3 = B.objects.create()
d1 = D.objects.create(b=b1)
d2 = D.objects.create(b=b2)
d3 = D.objects.create(b=b3)
d4 = D.objects.create()
A.objects.create(flag=None, content_object=b1)
A.objects.create(flag=True, content_object=b1)
A.objects.create(flag=True, content_object=b2)
self.assertQuerysetEqual(
D.objects.exclude(b__a__flag=None),
[d2], lambda x: x
)
self.assertQuerysetEqual(
D.objects.filter(b__a__flag=None),
[d1, d3, d4], lambda x: x
)
self.assertQuerysetEqual(
B.objects.filter(a__flag=None),
[b1, b3], lambda x: x
)
self.assertQuerysetEqual(
B.objects.exclude(a__flag=None),
[b2], lambda x: x
)
def test_extra_join_condition(self):
# A crude check that content_type_id is taken in account in the
# join/subquery condition.
self.assertIn("content_type_id", str(B.objects.exclude(a__flag=None).query).lower())
# No need for any joins - the join from inner query can be trimmed in
# this case (but not in the above case as no a objects at all for given
# B would then fail).
self.assertNotIn(" join ", str(B.objects.exclude(a__flag=True).query).lower())
self.assertIn("content_type_id", str(B.objects.exclude(a__flag=True).query).lower())