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Fixed #8046 -- The first filter() call on a related manager for many-to-many 

fields no longer creates duplicate copies of the join table(s). Basically, this
means filters on the join table (for ManyToManyField(through=...)) and complex
filters in the normal (non-through) case don't produce incorrect or duplicate
results.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@8472 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Malcolm Tredinnick 2008-08-22 22:00:28 +00:00
parent 6e36ce1429
commit d4d7bc175d
4 changed files with 80 additions and 43 deletions
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2
django/db/models/fields/related.py
View File

@ -376,7 +376,7 @@ def create_many_related_manager(superclass, through=False):
raise ValueError("%r instance needs to have a primary key value before a many-to-many relationship can be used." % instance.__class__.__name__)
def get_query_set(self):
return superclass.get_query_set(self).filter(**(self.core_filters))
return superclass.get_query_set(self)._next_is_sticky().filter(**(self.core_filters))
# If the ManyToMany relation has an intermediary model,
# the add and remove methods do not exist.

17
django/db/models/query.py
View File

@ -121,6 +121,7 @@ class QuerySet(object):
self.query = query or sql.Query(self.model, connection)
self._result_cache = None
self._iter = None
self._sticky_filter = False
########################
# PYTHON MAGIC METHODS #
@ -589,7 +590,10 @@ class QuerySet(object):
def _clone(self, klass=None, setup=False, **kwargs):
if klass is None:
klass = self.__class__
c = klass(model=self.model, query=self.query.clone())
query = self.query.clone()
if self._sticky_filter:
query.filter_is_sticky = True
c = klass(model=self.model, query=query)
c.__dict__.update(kwargs)
if setup and hasattr(c, '_setup_query'):
c._setup_query()
@ -607,6 +611,17 @@ class QuerySet(object):
except StopIteration:
self._iter = None
def _next_is_sticky(self):
"""
Indicates that the next filter call and the one following that should
be treated as a single filter. This is only important when it comes to
determining when to reuse tables for many-to-many filters. Required so
that we can filter naturally on the results of related managers.
"""
obj = self._clone()
obj._sticky_filter = True
return obj
def _merge_sanity_check(self, other):
"""
Checks that we are merging two comparable QuerySet classes. By default

50
django/db/models/sql/query.py
View File

@ -58,6 +58,8 @@ class Query(object):
self.select_fields = []
self.related_select_fields = []
self.dupe_avoidance = {}
self.used_aliases = set()
self.filter_is_sticky = False
# SQL-related attributes
self.select = []
@ -78,7 +80,7 @@ class Query(object):
# These are for extensions. The contents are more or less appended
# verbatim to the appropriate clause.
self.extra_select = SortedDict() # Maps col_alias -> col_sql.
self.extra_select = SortedDict() # Maps col_alias -> (col_sql, params).
self.extra_tables = ()
self.extra_where = ()
self.extra_params = ()
@ -185,6 +187,11 @@ class Query(object):
obj.extra_where = self.extra_where
obj.extra_params = self.extra_params
obj.extra_order_by = self.extra_order_by
if self.filter_is_sticky and self.used_aliases:
obj.used_aliases = self.used_aliases.copy()
else:
obj.used_aliases = set()
obj.filter_is_sticky = False
obj.__dict__.update(kwargs)
if hasattr(obj, '_setup_query'):
obj._setup_query()
@ -1148,31 +1155,32 @@ class Query(object):
Can also be used to add anything that has an 'add_to_query()' method.
"""
if used_aliases is None:
used_aliases = set()
used_aliases = self.used_aliases
if hasattr(q_object, 'add_to_query'):
# Complex custom objects are responsible for adding themselves.
q_object.add_to_query(self, used_aliases)
return
if self.where and q_object.connector != AND and len(q_object) > 1:
self.where.start_subtree(AND)
subtree = True
else:
subtree = False
connector = AND
for child in q_object.children:
if isinstance(child, Node):
self.where.start_subtree(connector)
self.add_q(child, used_aliases)
self.where.end_subtree()
if self.where and q_object.connector != AND and len(q_object) > 1:
self.where.start_subtree(AND)
subtree = True
else:
self.add_filter(child, connector, q_object.negated,
can_reuse=used_aliases)
connector = q_object.connector
if q_object.negated:
self.where.negate()
if subtree:
self.where.end_subtree()
subtree = False
connector = AND
for child in q_object.children:
if isinstance(child, Node):
self.where.start_subtree(connector)
self.add_q(child, used_aliases)
self.where.end_subtree()
else:
self.add_filter(child, connector, q_object.negated,
can_reuse=used_aliases)
connector = q_object.connector
if q_object.negated:
self.where.negate()
if subtree:
self.where.end_subtree()
if self.filter_is_sticky:
self.used_aliases = used_aliases
def setup_joins(self, names, opts, alias, dupe_multis, allow_many=True,
allow_explicit_fk=False, can_reuse=None):

54
tests/regressiontests/m2m_through_regress/models.py
View File

@ -8,7 +8,7 @@ class Membership(models.Model):
person = models.ForeignKey('Person')
group = models.ForeignKey('Group')
price = models.IntegerField(default=100)
def __unicode__(self):
return "%s is a member of %s" % (self.person.name, self.group.name)
@ -16,7 +16,7 @@ class UserMembership(models.Model):
user = models.ForeignKey(User)
group = models.ForeignKey('Group')
price = models.IntegerField(default=100)
def __unicode__(self):
return "%s is a user and member of %s" % (self.user.username, self.group.name)
@ -31,10 +31,10 @@ class Group(models.Model):
# Membership object defined as a class
members = models.ManyToManyField(Person, through=Membership)
user_members = models.ManyToManyField(User, through='UserMembership')
def __unicode__(self):
return self.name
__test__ = {'API_TESTS':"""
# Create some dummy data
>>> bob = Person.objects.create(name='Bob')
@ -46,7 +46,7 @@ __test__ = {'API_TESTS':"""
>>> frank = User.objects.create_user('frank','frank@example.com','password')
>>> jane = User.objects.create_user('jane','jane@example.com','password')
# Now test that the forward declared Membership works
# Now test that the forward declared Membership works
>>> Membership.objects.create(person=bob, group=rock)
<Membership: Bob is a member of Rock>
@ -83,7 +83,7 @@ Traceback (most recent call last):
...
AttributeError: Cannot use create() on a ManyToManyField which specifies an intermediary model. Use Membership's Manager instead.
# Now test that the intermediate with a relationship outside
# Now test that the intermediate with a relationship outside
# the current app (i.e., UserMembership) workds
>>> UserMembership.objects.create(user=frank, group=rock)
<UserMembership: frank is a user and member of Rock>
@ -100,11 +100,11 @@ AttributeError: Cannot use create() on a ManyToManyField which specifies an inte
>>> roll.user_members.all()
[<User: frank>]
# Regression test for #8134 --
# Regression test for #8134 --
# m2m-through models shouldn't be serialized as m2m fields on the model.
# First, clean up a lot of objects we don't need.
# The serialization test only requires three objects to work -
# First, clean up a lot of objects we don't need.
# The serialization test only requires three objects to work -
# one for each end of the m2m, plus the through model.
>>> User.objects.all().delete()
@ -117,24 +117,24 @@ AttributeError: Cannot use create() on a ManyToManyField which specifies an inte
>>> management.call_command('dumpdata', 'm2m_through_regress', format='json', indent=2)
[
{
"pk": 2,
"model": "m2m_through_regress.membership",
"pk": 2,
"model": "m2m_through_regress.membership",
"fields": {
"person": 1,
"price": 100,
"person": 1,
"price": 100,
"group": 2
}
},
},
{
"pk": 1,
"model": "m2m_through_regress.person",
"pk": 1,
"model": "m2m_through_regress.person",
"fields": {
"name": "Bob"
}
},
},
{
"pk": 2,
"model": "m2m_through_regress.group",
"pk": 2,
"model": "m2m_through_regress.group",
"fields": {
"name": "Roll"
}
@ -158,4 +158,18 @@ AttributeError: Cannot use create() on a ManyToManyField which specifies an inte
</object>
</django-objects>
"""}
## Regression test for #8046:
Check that we don't involve too many copies of the intermediate table when
doing a join.
>>> bob = Person.objects.create(name='Bob')
>>> jim = Person.objects.create(name='Jim')
>>> rock = Group.objects.create(name='Rock')
>>> roll = Group.objects.create(name='Roll')
>>> _ = Membership.objects.create(person=bob, group=rock)
>>> _ = Membership.objects.create(person=jim, group=rock, price=50)
>>> _ = Membership.objects.create(person=bob, group=roll, price=50)
>>> rock.members.filter(membership__price=50)
[<Person: Jim>]
"""}