From f84e32edadef8dac84f81b127ebdd4c61c543c0f Mon Sep 17 00:00:00 2001 From: Collin Anderson Date: Mon, 20 Mar 2017 20:26:23 -0400 Subject: [PATCH] Fixed #9475 -- allow add(), create(), etc for m2m with through --- .../db/models/fields/related_descriptors.py | 64 +++-------- docs/ref/models/relations.txt | 37 ++++-- docs/releases/2.1.txt | 6 + docs/topics/db/examples/many_to_many.txt | 5 +- docs/topics/db/models.txt | 46 ++++---- tests/m2m_through/models.py | 7 ++ tests/m2m_through/tests.py | 106 +++++++++--------- tests/m2m_through_regress/tests.py | 40 ++----- 8 files changed, 142 insertions(+), 169 deletions(-) diff --git a/django/db/models/fields/related_descriptors.py b/django/db/models/fields/related_descriptors.py index a5d4a514b7eda..6323d9ebb7ca8 100644 --- a/django/db/models/fields/related_descriptors.py +++ b/django/db/models/fields/related_descriptors.py @@ -906,32 +906,20 @@ def get_prefetch_queryset(self, instances, queryset=None): False, ) - def add(self, *objs): - if not rel.through._meta.auto_created: - opts = self.through._meta - raise AttributeError( - "Cannot use add() on a ManyToManyField which specifies an " - "intermediary model. Use %s.%s's Manager instead." % - (opts.app_label, opts.object_name) - ) + def add(self, *objs, through_defaults=None): self._remove_prefetched_objects() db = router.db_for_write(self.through, instance=self.instance) with transaction.atomic(using=db, savepoint=False): - self._add_items(self.source_field_name, self.target_field_name, *objs) + self._add_items( + self.source_field_name, self.target_field_name, *objs, through_defaults=through_defaults) # If this is a symmetrical m2m relation to self, add the mirror entry in the m2m table if self.symmetrical: - self._add_items(self.target_field_name, self.source_field_name, *objs) + self._add_items( + self.target_field_name, self.source_field_name, *objs, through_defaults=through_defaults) add.alters_data = True def remove(self, *objs): - if not rel.through._meta.auto_created: - opts = self.through._meta - raise AttributeError( - "Cannot use remove() on a ManyToManyField which specifies " - "an intermediary model. Use %s.%s's Manager instead." % - (opts.app_label, opts.object_name) - ) self._remove_prefetched_objects() self._remove_items(self.source_field_name, self.target_field_name, *objs) remove.alters_data = True @@ -955,15 +943,7 @@ def clear(self): ) clear.alters_data = True - def set(self, objs, *, clear=False): - if not rel.through._meta.auto_created: - opts = self.through._meta - raise AttributeError( - "Cannot set values on a ManyToManyField which specifies an " - "intermediary model. Use %s.%s's Manager instead." % - (opts.app_label, opts.object_name) - ) - + def set(self, objs, *, clear=False, through_defaults=None): # Force evaluation of `objs` in case it's a queryset whose value # could be affected by `manager.clear()`. Refs #19816. objs = tuple(objs) @@ -972,7 +952,7 @@ def set(self, objs, *, clear=False): with transaction.atomic(using=db, savepoint=False): if clear: self.clear() - self.add(*objs) + self.add(*objs, through_defaults=through_defaults) else: old_ids = set(self.using(db).values_list(self.target_field.target_field.attname, flat=True)) @@ -988,49 +968,41 @@ def set(self, objs, *, clear=False): new_objs.append(obj) self.remove(*old_ids) - self.add(*new_objs) + self.add(*new_objs, through_defaults=through_defaults) set.alters_data = True - def create(self, **kwargs): - # This check needs to be done here, since we can't later remove this - # from the method lookup table, as we do with add and remove. - if not self.through._meta.auto_created: - opts = self.through._meta - raise AttributeError( - "Cannot use create() on a ManyToManyField which specifies " - "an intermediary model. Use %s.%s's Manager instead." % - (opts.app_label, opts.object_name) - ) + def create(self, through_defaults=None, **kwargs): db = router.db_for_write(self.instance.__class__, instance=self.instance) new_obj = super(ManyRelatedManager, self.db_manager(db)).create(**kwargs) - self.add(new_obj) + self.add(new_obj, through_defaults=through_defaults) return new_obj create.alters_data = True - def get_or_create(self, **kwargs): + def get_or_create(self, through_defaults=None, **kwargs): db = router.db_for_write(self.instance.__class__, instance=self.instance) obj, created = super(ManyRelatedManager, self.db_manager(db)).get_or_create(**kwargs) # We only need to add() if created because if we got an object back # from get() then the relationship already exists. if created: - self.add(obj) + self.add(obj, through_defaults=through_defaults) return obj, created get_or_create.alters_data = True - def update_or_create(self, **kwargs): + def update_or_create(self, through_defaults=None, **kwargs): db = router.db_for_write(self.instance.__class__, instance=self.instance) obj, created = super(ManyRelatedManager, self.db_manager(db)).update_or_create(**kwargs) # We only need to add() if created because if we got an object back # from get() then the relationship already exists. if created: - self.add(obj) + self.add(obj, through_defaults=through_defaults) return obj, created update_or_create.alters_data = True - def _add_items(self, source_field_name, target_field_name, *objs): + def _add_items(self, source_field_name, target_field_name, *objs, through_defaults=None): # source_field_name: the PK fieldname in join table for the source object # target_field_name: the PK fieldname in join table for the target object # *objs - objects to add. Either object instances, or primary keys of object instances. + through_defaults = through_defaults or {} # If there aren't any objects, there is nothing to do. from django.db.models import Model @@ -1080,10 +1052,10 @@ def _add_items(self, source_field_name, target_field_name, *objs): # Add the ones that aren't there already self.through._default_manager.using(db).bulk_create([ - self.through(**{ + self.through(**dict(through_defaults, **{ '%s_id' % source_field_name: self.related_val[0], '%s_id' % target_field_name: obj_id, - }) + })) for obj_id in new_ids ]) diff --git a/docs/ref/models/relations.txt b/docs/ref/models/relations.txt index beffe1283e44b..c7090abc751ee 100644 --- a/docs/ref/models/relations.txt +++ b/docs/ref/models/relations.txt @@ -36,7 +36,7 @@ Related objects reference In this example, the methods below will be available both on ``topping.pizza_set`` and on ``pizza.toppings``. - .. method:: add(*objs, bulk=True) + .. method:: add(*objs, bulk=True, through_defaults=None) Adds the specified model objects to the related object set. @@ -62,7 +62,14 @@ Related objects reference some custom logic when a relationship is created, listen to the :data:`~django.db.models.signals.m2m_changed` signal. - .. method:: create(**kwargs) + The ``through_defaults`` argument can be used to specify values for + the new :ref:`an intermediate model ` instance. + + .. versionchanged:: 2.1 + + The ``through_defaults`` argument was added. + + .. method:: create(through_defaults=None, **kwargs) Creates a new object, saves it and puts it in the related object set. Returns the newly created object:: @@ -92,6 +99,13 @@ Related objects reference parameter ``blog`` to ``create()``. Django figures out that the new ``Entry`` object's ``blog`` field should be set to ``b``. + The ``through_defaults`` argument can be used to specify values for + the new :ref:`an intermediate model ` instance. + + .. versionchanged:: 2.1 + + The ``through_defaults`` argument was added. + .. method:: remove(*objs) Removes the specified model objects from the related object set:: @@ -125,6 +139,11 @@ Related objects reference :data:`~django.db.models.signals.post_save` signals and comes at the expense of performance. + .. versionchanged:: 2.1 + + The ``remove()`` method is now allowed on relationships with + custom intermediate models. + .. method:: clear() Removes all objects from the related object set:: @@ -139,7 +158,7 @@ Related objects reference :class:`~django.db.models.ForeignKey`\s where ``null=True`` and it also accepts the ``bulk`` keyword argument. - .. method:: set(objs, bulk=True, clear=False) + .. method:: set(objs, bulk=True, clear=False, through_defaults=None) Replace the set of related objects:: @@ -158,6 +177,9 @@ Related objects reference race conditions. For instance, new objects may be added to the database in between the call to ``clear()`` and the call to ``add()``. + The ``through_defaults`` argument can be used to specify values for + new :ref:`an intermediate model ` instances. + .. note:: Note that ``add()``, ``create()``, ``remove()``, ``clear()``, and @@ -165,11 +187,10 @@ Related objects reference related fields. In other words, there is no need to call ``save()`` on either end of the relationship. - Also, if you are using :ref:`an intermediate model - ` for a many-to-many relationship, then the - ``add()``, ``create()``, ``remove()``, and ``set()`` methods are - disabled. - If you use :meth:`~django.db.models.query.QuerySet.prefetch_related`, the ``add()``, ``remove()``, ``clear()``, and ``set()`` methods clear the prefetched cache. + + .. versionchanged:: 2.1 + + The ``through_defaults`` argument was added. diff --git a/docs/releases/2.1.txt b/docs/releases/2.1.txt index f2141dbb992bd..0a91eb5e3f7a1 100644 --- a/docs/releases/2.1.txt +++ b/docs/releases/2.1.txt @@ -164,6 +164,12 @@ Migrations Models ~~~~~~ +* The ``add()``, ``create()``, ``get_or_create()``, ``update_or_create()``, + ``set()``, and ``remove()`` methods are now allowed on many-to-many + relationships with custom intermediate models. There is a + ``through_defaults`` argument for specifying values for new intermediate + models. + * Models can now use ``__init_subclass__()`` from :pep:`487`. * A ``BinaryField`` may now be set to ``editable=True`` if you wish to include diff --git a/docs/topics/db/examples/many_to_many.txt b/docs/topics/db/examples/many_to_many.txt index 7173faaecafd8..1d81193030873 100644 --- a/docs/topics/db/examples/many_to_many.txt +++ b/docs/topics/db/examples/many_to_many.txt @@ -34,10 +34,7 @@ objects, and a ``Publication`` has multiple ``Article`` objects: ordering = ('headline',) What follows are examples of operations that can be performed using the Python -API facilities. Note that if you are using :ref:`an intermediate model -` for a many-to-many relationship, some of the related -manager's methods are disabled, so some of these examples won't work with such -models. +API facilities. Create a couple of ``Publications``:: diff --git a/docs/topics/db/models.txt b/docs/topics/db/models.txt index 4294c05ec2c6b..d4ac270709fdb 100644 --- a/docs/topics/db/models.txt +++ b/docs/topics/db/models.txt @@ -511,37 +511,34 @@ the intermediate model:: >>> beatles.members.all() , ]> -Unlike normal many-to-many fields, you *can't* use ``add()``, ``create()``, -or ``set()`` to create relationships:: +You can also use ``add()``, ``create()``, or ``set()`` to create relationships, +as long as your specify ``through_defaults`` for any required fields:: >>> # The following statements will not work - >>> beatles.members.add(john) - >>> beatles.members.create(name="George Harrison") - >>> beatles.members.set([john, paul, ringo, george]) - -Why? You can't just create a relationship between a ``Person`` and a ``Group`` -- you need to specify all the detail for the relationship required by the -``Membership`` model. The simple ``add``, ``create`` and assignment calls -don't provide a way to specify this extra detail. As a result, they are -disabled for many-to-many relationships that use an intermediate model. -The only way to create this type of relationship is to create instances of the -intermediate model. - -The :meth:`~django.db.models.fields.related.RelatedManager.remove` method is -disabled for similar reasons. For example, if the custom through table defined -by the intermediate model does not enforce uniqueness on the -``(model1, model2)`` pair, a ``remove()`` call would not provide enough -information as to which intermediate model instance should be deleted:: + >>> beatles.members.add(john, through_defaults={'date_joined': date(1960, 8, 1)}) + >>> beatles.members.create(name="George Harrison", through_defaults={'date_joined': date(1960, 8, 1)}) + >>> beatles.members.set([john, paul, ringo, george], through_defaults={'date_joined': date(1960, 8, 1)}) + +The simple ``add``, ``create`` and ``set`` calls don't provide a way to +specify different details for different objects. You may prefer to create +instances of the intermediate model directly instead. + +If the custom through table defined by the intermediate model does not enforce +uniqueness on the ``(model1, model2)`` pair, allowing multiple values, the +:meth:`~django.db.models.fields.related.RelatedManager.remove` call will +remove all intermediate model instances:: >>> Membership.objects.create(person=ringo, group=beatles, ... date_joined=date(1968, 9, 4), ... invite_reason="You've been gone for a month and we miss you.") >>> beatles.members.all() , , ]> - >>> # This will not work because it cannot tell which membership to remove + >>> # This deletes both of the intermediate model instances for Ringo Starr >>> beatles.members.remove(ringo) + >>> beatles.members.all() + ]> -However, the :meth:`~django.db.models.fields.related.RelatedManager.clear` +The :meth:`~django.db.models.fields.related.RelatedManager.clear` method can be used to remove all many-to-many relationships for an instance:: >>> # Beatles have broken up @@ -550,10 +547,9 @@ method can be used to remove all many-to-many relationships for an instance:: >>> Membership.objects.all() -Once you have established the many-to-many relationships by creating instances -of your intermediate model, you can issue queries. Just as with normal -many-to-many relationships, you can query using the attributes of the -many-to-many-related model:: +Once you have established the many-to-many relationships, you can issue +queries. Just as with normal many-to-many relationships, you can query using +the attributes of the many-to-many-related model:: # Find all the groups with a member whose name starts with 'Paul' >>> Group.objects.filter(members__name__startswith='Paul') diff --git a/tests/m2m_through/models.py b/tests/m2m_through/models.py index 5f9fba27a7def..443d0ad226ce7 100644 --- a/tests/m2m_through/models.py +++ b/tests/m2m_through/models.py @@ -23,6 +23,7 @@ class Group(models.Model): through='TestNoDefaultsOrNulls', related_name="testnodefaultsnonulls", ) + required_through = models.ManyToManyField(Person, through='RequiredThrough', related_name='required_through') class Meta: ordering = ('name',) @@ -69,6 +70,12 @@ class TestNoDefaultsOrNulls(models.Model): nodefaultnonull = models.CharField(max_length=5) +class RequiredThrough(models.Model): + person = models.ForeignKey(Person, models.CASCADE) + group = models.ForeignKey(Group, models.CASCADE) + required = models.IntegerField() + + class PersonSelfRefM2M(models.Model): name = models.CharField(max_length=5) friends = models.ManyToManyField('self', through="Friendship", symmetrical=False) diff --git a/tests/m2m_through/tests.py b/tests/m2m_through/tests.py index 930f5e848c6a0..8c299d7f772a7 100644 --- a/tests/m2m_through/tests.py +++ b/tests/m2m_through/tests.py @@ -1,6 +1,7 @@ from datetime import datetime from operator import attrgetter +from django.db import IntegrityError from django.test import TestCase from .models import ( @@ -56,51 +57,59 @@ def test_filter_on_intermediate_model(self): expected ) - def test_cannot_use_add_on_m2m_with_intermediary_model(self): - msg = 'Cannot use add() on a ManyToManyField which specifies an intermediary model' + def test_add_on_m2m_with_intermediary_model(self): + self.rock.members.add(self.bob, through_defaults={'invite_reason': 'He is good.'}) - with self.assertRaisesMessage(AttributeError, msg): - self.rock.members.add(self.bob) - - self.assertQuerysetEqual( + self.assertSequenceEqual( self.rock.members.all(), - [] + [self.bob] ) + self.assertEqual(self.rock.membership_set.get().invite_reason, 'He is good.') - def test_cannot_use_create_on_m2m_with_intermediary_model(self): - msg = 'Cannot use create() on a ManyToManyField which specifies an intermediary model' - - with self.assertRaisesMessage(AttributeError, msg): - self.rock.members.create(name='Annie') + def test_create_on_m2m_with_intermediary_model(self): + annie = self.rock.members.create(name='Annie', through_defaults={'invite_reason': 'She was just awesome.'}) - self.assertQuerysetEqual( + self.assertSequenceEqual( self.rock.members.all(), - [] + [annie] ) + self.assertEqual(self.rock.membership_set.get().invite_reason, 'She was just awesome.') - def test_cannot_use_remove_on_m2m_with_intermediary_model(self): + def test_create_on_m2m_with_intermediary_model_value_required(self): + with self.assertRaises(IntegrityError): + self.rock.required_through.add(self.jim) + + def test_remove_on_m2m_with_intermediary_model(self): Membership.objects.create(person=self.jim, group=self.rock) - msg = 'Cannot use remove() on a ManyToManyField which specifies an intermediary model' - with self.assertRaisesMessage(AttributeError, msg): - self.rock.members.remove(self.jim) + self.rock.members.remove(self.jim) - self.assertQuerysetEqual( + self.assertSequenceEqual( self.rock.members.all(), - ['Jim'], - attrgetter("name") + [], + ) + + def test_remove_on_m2m_with_intermediary_model_multiple(self): + Membership.objects.create(person=self.jim, group=self.rock, invite_reason='1') + Membership.objects.create(person=self.jim, group=self.rock, invite_reason='2') + self.assertSequenceEqual( + self.rock.members.all(), + [self.jim, self.jim] + ) + self.rock.members.remove(self.jim) + self.assertSequenceEqual( + self.rock.members.all(), + [], ) - def test_cannot_use_setattr_on_m2m_with_intermediary_model(self): - msg = 'Cannot set values on a ManyToManyField which specifies an intermediary model' + def test_set_on_m2m_with_intermediary_model(self): members = list(Person.objects.filter(name__in=['Bob', 'Jim'])) - with self.assertRaisesMessage(AttributeError, msg): - self.rock.members.set(members) + self.rock.members.set(members) - self.assertQuerysetEqual( + self.assertSequenceEqual( self.rock.members.all(), - [] + [self.bob, self.jim] ) def test_clear_removes_all_the_m2m_relationships(self): @@ -125,51 +134,40 @@ def test_retrieve_reverse_intermediate_items(self): attrgetter("name") ) - def test_cannot_use_add_on_reverse_m2m_with_intermediary_model(self): - msg = 'Cannot use add() on a ManyToManyField which specifies an intermediary model' + def test_add_on_reverse_m2m_with_intermediary_model(self): + self.bob.group_set.add(self.rock) - with self.assertRaisesMessage(AttributeError, msg): - self.bob.group_set.add(self.bob) - - self.assertQuerysetEqual( + self.assertSequenceEqual( self.bob.group_set.all(), - [] + [self.rock] ) - def test_cannot_use_create_on_reverse_m2m_with_intermediary_model(self): - msg = 'Cannot use create() on a ManyToManyField which specifies an intermediary model' + def test_create_on_reverse_m2m_with_intermediary_model(self): + funk = self.bob.group_set.create(name='Funk') - with self.assertRaisesMessage(AttributeError, msg): - self.bob.group_set.create(name='Funk') - - self.assertQuerysetEqual( + self.assertSequenceEqual( self.bob.group_set.all(), - [] + [funk] ) - def test_cannot_use_remove_on_reverse_m2m_with_intermediary_model(self): + def test_remove_on_reverse_m2m_with_intermediary_model(self): Membership.objects.create(person=self.bob, group=self.rock) - msg = 'Cannot use remove() on a ManyToManyField which specifies an intermediary model' - with self.assertRaisesMessage(AttributeError, msg): - self.bob.group_set.remove(self.rock) + self.bob.group_set.remove(self.rock) - self.assertQuerysetEqual( + self.assertSequenceEqual( self.bob.group_set.all(), - ['Rock'], - attrgetter('name') + [], ) - def test_cannot_use_setattr_on_reverse_m2m_with_intermediary_model(self): - msg = 'Cannot set values on a ManyToManyField which specifies an intermediary model' + def test_set_on_reverse_m2m_with_intermediary_model(self): members = list(Group.objects.filter(name__in=['Rock', 'Roll'])) - with self.assertRaisesMessage(AttributeError, msg): - self.bob.group_set.set(members) + self.bob.group_set.set(members) - self.assertQuerysetEqual( + self.assertSequenceEqual( self.bob.group_set.all(), - [] + [self.rock, self.roll] ) def test_clear_on_reverse_removes_all_the_m2m_relationships(self): diff --git a/tests/m2m_through_regress/tests.py b/tests/m2m_through_regress/tests.py index 64be4252bd115..ac5ed91cabf5f 100644 --- a/tests/m2m_through_regress/tests.py +++ b/tests/m2m_through_regress/tests.py @@ -47,41 +47,17 @@ def test_retrieve_forward_m2m_items(self): ] ) - def test_cannot_use_setattr_on_reverse_m2m_with_intermediary_model(self): - msg = ( - "Cannot set values on a ManyToManyField which specifies an " - "intermediary model. Use m2m_through_regress.Membership's Manager " - "instead." - ) - with self.assertRaisesMessage(AttributeError, msg): - self.bob.group_set.set([]) + def test_set_on_reverse_m2m_with_intermediary_model(self): + self.bob.group_set.set([]) - def test_cannot_use_setattr_on_forward_m2m_with_intermediary_model(self): - msg = ( - "Cannot set values on a ManyToManyField which specifies an " - "intermediary model. Use m2m_through_regress.Membership's Manager " - "instead." - ) - with self.assertRaisesMessage(AttributeError, msg): - self.roll.members.set([]) + def test_set_on_forward_m2m_with_intermediary_model(self): + self.roll.members.set([]) - def test_cannot_use_create_on_m2m_with_intermediary_model(self): - msg = ( - "Cannot use create() on a ManyToManyField which specifies an " - "intermediary model. Use m2m_through_regress.Membership's " - "Manager instead." - ) - with self.assertRaisesMessage(AttributeError, msg): - self.rock.members.create(name="Anne") + def test_create_on_m2m_with_intermediary_model(self): + self.rock.members.create(name="Anne") - def test_cannot_use_create_on_reverse_m2m_with_intermediary_model(self): - msg = ( - "Cannot use create() on a ManyToManyField which specifies an " - "intermediary model. Use m2m_through_regress.Membership's " - "Manager instead." - ) - with self.assertRaisesMessage(AttributeError, msg): - self.bob.group_set.create(name="Funk") + def test_create_on_reverse_m2m_with_intermediary_model(self): + self.bob.group_set.create(name="Funk") def test_retrieve_reverse_m2m_items_via_custom_id_intermediary(self): self.assertQuerysetEqual(