Ticket #6095: 6095-r8090.2.diff

django/db/models/fields/related.py

@@ -23 +23 @@
-
-pending_lookups = {}
-
-
+, operation
-    """
-    Adds a lookup on ``cls`` when a related field is defined using a string,
-    i.e.::
@@ -45 +45 @@
-    If the other model hasn't yet been loaded -- almost a given if you're using
-    lazy relationships -- then the relation won't be set up until the
-    class_prepared signal fires at the end of model initialization.
+    
+    operation is the work that must be performed once the relation can be resolved.
-    """
-    # Check for recursive relations
-    if relation == RECURSIVE_RELATIONSHIP_CONSTANT:
@@ -66 +68 @@
-    # is prepared.
-    model = get_model(app_label, model_name, False)
-    if model:
-
-
+
-    else:
-        key = (app_label, model_name)
-
+, operation
-        pending_lookups.setdefault(key, []).append(value)
-
-def do_pending_lookups(sender):
@@ -78 +79 @@
-    Handle any pending relations to the sending model. Sent from class_prepared.
-    """
-    key = (sender._meta.app_label, sender.__name__)
-
-
-
+
+
-
-dispatcher.connect(do_pending_lookups, signal=signals.class_prepared)
-
@@ -108 +108 @@
-
-        other = self.rel.to
-        if isinstance(other, basestring):
-
+
+
+
+
-        else:
-            self.do_related_class(other, cls)
-
@@ -339 +342 @@
-            manager.clear()
-        manager.add(*value)
-
-
+, through=False
-    """Creates a manager that subclasses 'superclass' (which is a Manager)
-    and adds behavior for many-to-many related objects."""
-    class ManyRelatedManager(superclass):
@@ -353 +356 @@
-            self.join_table = join_table
-            self.source_col_name = source_col_name
-            self.target_col_name = target_col_name
+            self.through = through
-            self._pk_val = self.instance._get_pk_val()
-            if self._pk_val is None:
-                raise ValueError("%r instance needs to have a primary key value before a many-to-many relationship can be used." % instance.__class__.__name__)
@@ -360 +364 @@
-        def get_query_set(self):
-            return superclass.get_query_set(self).filter(**(self.core_filters))
-
-
-
+
+
+
+
+
-
-
-
-
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+    
+    
+    
+    
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+    
+    
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+    
+    
+    
+    
-
-        def clear(self):
-            self._clear_items(self.source_col_name)
@@ -385 +392 @@
-        clear.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 through is not None:
+                raise AttributeError, "Cannot use create() on a ManyToManyField which specifies an intermediary model. Use %s's Manager instead." % through
-            new_obj = self.model(**kwargs)
-            new_obj.save()
-            self.add(new_obj)
@@ -472 +483 @@
-        # model's default manager.
-        rel_model = self.related.model
-        superclass = rel_model._default_manager.__class__
-
+, self.related.field.rel.through
-
-        qn = connection.ops.quote_name
-        manager = RelatedManager(
@@ -491 +502 @@
-        if instance is None:
-            raise AttributeError, "Manager must be accessed via instance"
-
+        through = getattr(self.related.field.rel, 'through', None)
+        if through is not None:
+            raise AttributeError, "Cannot set values on a ManyToManyField which specifies an intermediary model. Use %s's Manager instead." % through
+
-        manager = self.__get__(instance)
-        manager.clear()
-        manager.add(*value)
@@ -513 +528 @@
-        # model's default manager.
-        rel_model=self.field.rel.to
-        superclass = rel_model._default_manager.__class__
-
+, self.field.rel.through
-
-        qn = connection.ops.quote_name
-        manager = RelatedManager(
@@ -532 +547 @@
-        if instance is None:
-            raise AttributeError, "Manager must be accessed via instance"
-
+        through = getattr(self.field.rel, 'through', None)
+        if through is not None:
+            raise AttributeError, "Cannot set values on a ManyToManyField which specifies an intermediary model.  Use %s's Manager instead." % through
+
-        manager = self.__get__(instance)
-        manager.clear()
-        manager.add(*value)
@@ -583 +602 @@
-
-class ManyToManyRel(object):
-    def __init__(self, to, num_in_admin=0, related_name=None,
-
+, through=None
-        self.to = to
-        self.num_in_admin = num_in_admin
-        self.related_name = related_name
@@ -593 +612 @@
-        self.edit_inline = False
-        self.symmetrical = symmetrical
-        self.multiple = True
+        self.through = through
-
+
-class ForeignKey(RelatedField, Field):
-    empty_strings_allowed = False
-    def __init__(self, to, to_field=None, rel_class=ManyToOneRel, **kwargs):
@@ -718 +739 @@
-class ManyToManyField(RelatedField, Field):
-    def __init__(self, to, **kwargs):
-        kwargs['verbose_name'] = kwargs.get('verbose_name', None)
+        self.symmetrical_specified = kwargs.get('symmetrical', None) is not None
-        kwargs['rel'] = ManyToManyRel(to,
-            num_in_admin=kwargs.pop('num_in_admin', 0),
-            related_name=kwargs.pop('related_name', None),
-            limit_choices_to=kwargs.pop('limit_choices_to', None),
-
+
+
+
-        self.db_table = kwargs.pop('db_table', None)
+        if kwargs['rel'].through is not None:
+            self.creates_table = False
+            assert self.db_table is None, "Cannot specify a db_table if an intermediary model is used."
+        else:
+            self.creates_table = True
+
-        Field.__init__(self, **kwargs)
-
-        msg = ugettext_lazy('Hold down "Control", or "Command" on a Mac, to select more than one.')
@@ -738 +768 @@
-
-    def _get_m2m_db_table(self, opts):
-        "Function that can be curried to provide the m2m table name for this relation"
-
+
+
+
-            return self.db_table
-        else:
-            return '%s_%s' % (opts.db_table, self.name)
-
-    def _get_m2m_column_name(self, related):
-        "Function that can be curried to provide the source column name for the m2m table"
+        if self.rel.through is not None:
+            for f in self.rel.through_model._meta.fields:
+                if hasattr(f,'rel') and f.rel and f.rel.to == related.model:
+                    return f.column
-        # If this is an m2m relation to self, avoid the inevitable name clash
-
+el
-            return 'from_' + related.model._meta.object_name.lower() + '_id'
-        else:
-            return related.model._meta.object_name.lower() + '_id'
-
-    def _get_m2m_reverse_name(self, related):
-        "Function that can be curried to provide the related column name for the m2m table"
+        if self.rel.through is not None:
+            found = False
+            for f in self.rel.through_model._meta.fields:
+                if hasattr(f,'rel') and f.rel and f.rel.to == related.parent_model:
+                    if related.model == related.parent_model:
+                        # If this is an m2m-intermediate to self, 
+                        # the first foreign key you find will be 
+                        # the source column. Keep searching for
+                        # the second foreign key.
+                        if found:
+                            return f.column
+                        else:
+                            found = True
+                    else:
+                        return f.column
-        # If this is an m2m relation to self, avoid the inevitable name clash
-
+el
-            return 'to_' + related.parent_model._meta.object_name.lower() + '_id'
-        else:
-            return related.parent_model._meta.object_name.lower() + '_id'
@@ -797 +848 @@
-
-        # Set up the accessor for the m2m table name for the relation
-        self.m2m_db_table = curry(self._get_m2m_db_table, cls._meta)
-
+
+
+
+
+
+
+
+
+
+
+
-        if isinstance(self.rel.to, basestring):
-            target = self.rel.to
-        else:

django/core/management/validation.py

@@ -102 +102 @@
-                        if r.get_accessor_name() == rel_query_name:
-                            e.add(opts, "Reverse query name for field '%s' clashes with related field '%s.%s'. Add a related_name argument to the definition for '%s'." % (f.name, rel_opts.object_name, r.get_accessor_name(), f.name))
-
+        seen_intermediary_signatures = [] 
-        for i, f in enumerate(opts.local_many_to_many):
-            # Check to see if the related m2m field will clash with any
-            # existing fields, m2m fields, m2m related objects or related
@@ -112 +113 @@
-                # so skip the next section
-                if isinstance(f.rel.to, (str, unicode)):
-                    continue
-
+
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+
-            rel_opts = f.rel.to._meta
-            rel_name = RelatedObject(f.rel.to, cls, f).get_accessor_name()
-            rel_query_name = f.related_query_name()

django/core/management/sql.py

@@ -353 +353 @@
-    qn = connection.ops.quote_name
-    inline_references = connection.features.inline_fk_references
-    for f in opts.local_many_to_many:
-not isinstance(f.rel, generic.GenericRel)
+f.creates_table
-            tablespace = f.db_tablespace or opts.db_tablespace
-            if tablespace and connection.features.supports_tablespaces: 
-                tablespace_sql = ' ' + connection.ops.tablespace_sql(tablespace, inline=True)

django/contrib/admin/options.py

@@ -161 +161 @@
-                kwargs['empty_label'] = db_field.blank and _('None') or None
-            else:
-                if isinstance(db_field, models.ManyToManyField):
-
+
+
+
+
-                        kwargs['widget'] = widgets.ManyToManyRawIdWidget(db_field.rel)
-                        kwargs['help_text'] = ''
-                    elif db_field.name in (list(self.filter_vertical) + list(self.filter_horizontal)):

django/contrib/contenttypes/generic.py

@@ -104 +104 @@
-                            limit_choices_to=kwargs.pop('limit_choices_to', None),
-                            symmetrical=kwargs.pop('symmetrical', True))
-
+        # By its very nature, a GenericRelation doesn't create a table.
+        self.creates_table = False
+
-        # Override content-type/object-id field names on the related class
-        self.object_id_field_name = kwargs.pop("object_id_field", "object_id")
-        self.content_type_field_name = kwargs.pop("content_type_field", "content_type")

tests/modeltests/invalid_models/models.py

@@ -110 +110 @@
-class MissingRelations(models.Model):
-    rel1 = models.ForeignKey("Rel1")
-    rel2 = models.ManyToManyField("Rel2")
+    
+class MissingManualM2MModel(models.Model):
+    name = models.CharField(max_length=5)
+    missing_m2m = models.ManyToManyField(Model, through="MissingM2MModel")
+    
+class Person(models.Model):
+    name = models.CharField(max_length=5)
-
+class Group(models.Model):
+    name = models.CharField(max_length=5)
+    primary = models.ManyToManyField(Person, through="Membership", related_name="primary")
+    secondary = models.ManyToManyField(Person, through="Membership", related_name="secondary")
+    tertiary = models.ManyToManyField(Person, through="RelationshipDoubleFK", related_name="tertiary")
+
+class GroupTwo(models.Model):
+    name = models.CharField(max_length=5)
+    primary = models.ManyToManyField(Person, through="Membership")
+    secondary = models.ManyToManyField(Group, through="MembershipMissingFK")
+
+class Membership(models.Model):
+    person = models.ForeignKey(Person)
+    group = models.ForeignKey(Group)
+    not_default_or_null = models.CharField(max_length=5)
+
+class MembershipMissingFK(models.Model):
+    person = models.ForeignKey(Person)
+
+class PersonSelfRefM2M(models.Model):
+    name = models.CharField(max_length=5)
+    friends = models.ManyToManyField('self', through="Relationship", symmetrical=True)
+    too_many_friends = models.ManyToManyField('self', through="RelationshipTripleFK")
+
+class Relationship(models.Model):
+    first = models.ForeignKey(PersonSelfRefM2M, related_name="rel_from_set")
+    second = models.ForeignKey(PersonSelfRefM2M, related_name="rel_to_set")
+    date_added = models.DateTimeField()
+
+class RelationshipTripleFK(models.Model):
+    first = models.ForeignKey(PersonSelfRefM2M, related_name="rel_from_set_2")
+    second = models.ForeignKey(PersonSelfRefM2M, related_name="rel_to_set_2")
+    third = models.ForeignKey(PersonSelfRefM2M, related_name="too_many_by_far")
+    date_added = models.DateTimeField()
+
+class RelationshipDoubleFK(models.Model):
+    first = models.ForeignKey(Person, related_name="first_related_name")
+    second = models.ForeignKey(Person, related_name="second_related_name")
+    third = models.ForeignKey(Group, related_name="rel_to_set")
+    date_added = models.DateTimeField()
+
-model_errors = """invalid_models.fielderrors: "charfield": CharFields require a "max_length" attribute.
-invalid_models.fielderrors: "decimalfield": DecimalFields require a "decimal_places" attribute.
-invalid_models.fielderrors: "decimalfield": DecimalFields require a "max_digits" attribute.
@@ -195 +243 @@
-invalid_models.selfclashm2m: Reverse query name for m2m field 'm2m_4' clashes with field 'SelfClashM2M.selfclashm2m'. Add a related_name argument to the definition for 'm2m_4'.
-invalid_models.missingrelations: 'rel2' has m2m relation with model Rel2, which has not been installed
-invalid_models.missingrelations: 'rel1' has relation with model Rel1, which has not been installed
+invalid_models.group: The model Group has two manually-defined m2m relations through the model Membership, which is not permitted.  Please consider using an extra field on your intermediary model instead.
+invalid_models.grouptwo: 'primary' has a manually-defined m2m relation through model Membership, which does not have foreign keys to Person and GroupTwo
+invalid_models.grouptwo: 'secondary' has a manually-defined m2m relation through model MembershipMissingFK, which does not have foreign keys to Group and GroupTwo
+invalid_models.missingmanualm2mmodel: 'missing_m2m' specifies an m2m relation through model MissingM2MModel, which has not been installed
+invalid_models.group: Intermediary model RelationshipDoubleFK has more than one foreign key to one of its sides, Person, which is ambiguous and is not permitted.
+invalid_models.personselfrefm2m: The symmetrical field has no meaning on m2m relations with intermediary models.
+invalid_models.personselfrefm2m: Intermediary model RelationshipTripleFK has more than two foreign keys through itself, which is ambiguous and is not permitted.
-"""

tests/modeltests/m2m_through/models.py

@@ +1 @@
+from django.db import models
+from datetime import datetime
+
+# M2M described on one of the models
+class Person(models.Model):
+    name = models.CharField(max_length=128)
+
+    def __unicode__(self):
+        return self.name
+
+class Group(models.Model):
+    name = models.CharField(max_length=128)
+    members = models.ManyToManyField(Person, through='Membership')
+    custom_members = models.ManyToManyField(Person, through='CustomMembership', related_name="custom")
+    nodefaultsnonulls = models.ManyToManyField(Person, through='TestNoDefaultsOrNulls', related_name="testnodefaultsnonulls")
+    
+    def __unicode__(self):
+        return self.name
+
+class Membership(models.Model):
+    person = models.ForeignKey(Person)
+    group = models.ForeignKey(Group)
+    date_joined = models.DateTimeField(default=datetime.now)
+    invite_reason = models.CharField(max_length=64, null=True)
+    
+    def __unicode__(self):
+        return "%s is a member of %s" % (self.person.name, self.group.name)
+
+class CustomMembership(models.Model):
+    person = models.ForeignKey(Person, db_column="custom_person_column", related_name="custom_person_related_name")
+    group = models.ForeignKey(Group)
+    weird_fk = models.ForeignKey(Membership, null=True)
+    date_joined = models.DateTimeField(default=datetime.now)
+    
+    def __unicode__(self):
+        return "%s is a member of %s" % (self.person.name, self.group.name)
+    
+    class Meta:
+        db_table = "test_table"
+
+class TestNoDefaultsOrNulls(models.Model):
+    person = models.ForeignKey(Person)
+    group = models.ForeignKey(Group)
+    nodefaultnonull = models.CharField(max_length=5)
+
+class PersonSelfRefM2M(models.Model):
+    name = models.CharField(max_length=5)
+    friends = models.ManyToManyField('self', through="Friendship")
+    
+    def __unicode__(self):
+        return self.name
+
+class Friendship(models.Model):
+    first = models.ForeignKey(PersonSelfRefM2M, related_name="rel_from_set")
+    second = models.ForeignKey(PersonSelfRefM2M, related_name="rel_to_set")
+    date_friended = models.DateTimeField()
+
+__test__ = {'API_TESTS':"""
+>>> from datetime import datetime
+
+### Creation and Saving Tests ###
+
+>>> bob = Person.objects.create(name='Bob')
+>>> jim = Person.objects.create(name='Jim')
+>>> jane = Person.objects.create(name='Jane')
+>>> rock = Group.objects.create(name='Rock')
+>>> roll = Group.objects.create(name='Roll')
+
+# We start out by making sure that the Group 'rock' has no members.
+>>> rock.members.all()
+[]
+
+# To make Jim a member of Group Rock, simply create a Membership object.
+>>> m1 = Membership.objects.create(person=jim, group=rock)
+
+# We can do the same for Jane and Rock.
+>>> m2 = Membership.objects.create(person=jane, group=rock)
+
+# Let's check to make sure that it worked.  Jane and Jim should be members of Rock.
+>>> rock.members.all()
+[<Person: Jim>, <Person: Jane>]
+
+# Now we can add a bunch more Membership objects to test with.
+>>> m3 = Membership.objects.create(person=bob, group=roll)
+>>> m4 = Membership.objects.create(person=jim, group=roll)
+>>> m5 = Membership.objects.create(person=jane, group=roll)
+
+# We can get Jim's Group membership as with any ForeignKey.
+>>> jim.group_set.all()
+[<Group: Rock>, <Group: Roll>]
+
+# Querying the intermediary model works like normal.  
+# In this case we get Jane's membership to Rock.
+>>> m = Membership.objects.get(person=jane, group=rock)
+>>> m
+<Membership: Jane is a member of Rock>
+
+# Now we set some date_joined dates for further testing.
+>>> m2.invite_reason = "She was just awesome."
+>>> m2.date_joined = datetime(2006, 1, 1)
+>>> m2.save()
+
+>>> m5.date_joined = datetime(2004, 1, 1)
+>>> m5.save()
+
+>>> m3.date_joined = datetime(2004, 1, 1)
+>>> m3.save()
+
+# It's not only get that works. Filter works like normal as well.
+>>> Membership.objects.filter(person=jim)
+[<Membership: Jim is a member of Rock>, <Membership: Jim is a member of Roll>]
+
+
+### Forward Descriptors Tests ###
+
+# Due to complications with adding via an intermediary model, 
+# the add method is not provided.
+>>> rock.members.add(bob)
+Traceback (most recent call last):
+...
+AttributeError: 'ManyRelatedManager' object has no attribute 'add'
+
+# Create is also disabled as it suffers from the same problems as add.
+>>> rock.members.create(name='Anne')
+Traceback (most recent call last):
+...
+AttributeError: Cannot use create() on a ManyToManyField which specifies an intermediary model. Use Membership's Manager instead.
+
+# Remove has similar complications, and is not provided either.
+>>> rock.members.remove(jim)
+Traceback (most recent call last):
+...
+AttributeError: 'ManyRelatedManager' object has no attribute 'remove'
+
+# Here we back up the list of all members of Rock.
+>>> backup = list(rock.members.all())
+
+# ...and we verify that it has worked.
+>>> backup
+[<Person: Jim>, <Person: Jane>]
+
+# The clear function should still work.
+>>> rock.members.clear()
+
+# Now there will be no members of Rock.
+>>> rock.members.all()
+[]
+
+# Assignment should not work with models specifying a through model for many of
+# the same reasons as adding.
+>>> rock.members = backup
+Traceback (most recent call last):
+...
+AttributeError: Cannot set values on a ManyToManyField which specifies an intermediary model.  Use Membership's Manager instead.
+
+# Let's re-save those instances that we've cleared.
+>>> m1.save()
+>>> m2.save()
+
+# Verifying that those instances were re-saved successfully.
+>>> rock.members.all()
+[<Person: Jim>, <Person: Jane>]
+
+
+### Reverse Descriptors Tests ###
+
+# Due to complications with adding via an intermediary model, 
+# the add method is not provided.
+>>> bob.group_set.add(rock)
+Traceback (most recent call last):
+...
+AttributeError: 'ManyRelatedManager' object has no attribute 'add'
+
+# Create is also disabled as it suffers from the same problems as add.
+>>> bob.group_set.create(name='Funk')
+Traceback (most recent call last):
+...
+AttributeError: Cannot use create() on a ManyToManyField which specifies an intermediary model. Use Membership's Manager instead.
+
+# Remove has similar complications, and is not provided either.
+>>> jim.group_set.remove(rock)
+Traceback (most recent call last):
+...
+AttributeError: 'ManyRelatedManager' object has no attribute 'remove'
+
+# Here we back up the list of all of Jim's groups.
+>>> backup = list(jim.group_set.all())
+>>> backup
+[<Group: Rock>, <Group: Roll>]
+
+# The clear function should still work.
+>>> jim.group_set.clear()
+
+# Now Jim will be in no groups.
+>>> jim.group_set.all()
+[]
+
+# Assignment should not work with models specifying a through model for many of
+# the same reasons as adding.
+>>> jim.group_set = backup
+Traceback (most recent call last):
+...
+AttributeError: Cannot set values on a ManyToManyField which specifies an intermediary model.  Use Membership's Manager instead.
+
+# Let's re-save those instances that we've cleared.
+>>> m1.save()
+>>> m4.save()
+
+# Verifying that those instances were re-saved successfully.
+>>> jim.group_set.all()
+[<Group: Rock>, <Group: Roll>]
+
+### Custom Tests ###
+
+# Let's see if we can query through our second relationship.
+>>> rock.custom_members.all()
+[]
+
+# We can query in the opposite direction as well.
+>>> bob.custom.all()
+[]
+
+# Let's create some membership objects in this custom relationship.
+>>> cm1 = CustomMembership.objects.create(person=bob, group=rock)
+>>> cm2 = CustomMembership.objects.create(person=jim, group=rock)
+
+# If we get the number of people in Rock, it should be both Bob and Jim.
+>>> rock.custom_members.all()
+[<Person: Bob>, <Person: Jim>]
+
+# Bob should only be in one custom group.
+>>> bob.custom.all()
+[<Group: Rock>]
+
+# Let's make sure our new descriptors don't conflict with the FK related_name.
+>>> bob.custom_person_related_name.all()
+[<CustomMembership: Bob is a member of Rock>]
+
+### SELF-REFERENTIAL TESTS ###
+
+# Let's first create a person who has no friends.
+>>> tony = PersonSelfRefM2M.objects.create(name="Tony")
+>>> tony.friends.all()
+[]
+
+# Now let's create another person for Tony to be friends with.
+>>> chris = PersonSelfRefM2M.objects.create(name="Chris")
+>>> f = Friendship.objects.create(first=tony, second=chris, date_friended=datetime.now())
+
+# Tony should now show that Chris is his friend.
+>>> tony.friends.all()
+[<PersonSelfRefM2M: Chris>]
+
+# But we haven't established that Chris is Tony's Friend.
+>>> chris.friends.all()
+[]
+
+# So let's do that now.
+>>> f2 = Friendship.objects.create(first=chris, second=tony, date_friended=datetime.now())
+
+# Having added Chris as a friend, let's make sure that his friend set reflects
+# that addition.
+>>> chris.friends.all()
+[<PersonSelfRefM2M: Tony>]
+
+# Chris gets mad and wants to get rid of all of his friends.
+>>> chris.friends.clear()
+
+# Now he should not have any more friends.
+>>> chris.friends.all()
+[]
+
+# Since this is a symmetrical relation, Tony's friend link is deleted as well.
+>>> tony.friends.all()
+[]
+
+
+
+### QUERY TESTS ###
+
+# We can query for the related model by using its attribute name (members, in 
+# this case).
+>>> Group.objects.filter(members__name='Bob')
+[<Group: Roll>]
+
+# To query through the intermediary model, we specify its model name.
+# In this case, membership.
+>>> Group.objects.filter(membership__invite_reason="She was just awesome.")
+[<Group: Rock>]
+
+# If we want to query in the reverse direction by the related model, use its
+# model name (group, in this case).
+>>> Person.objects.filter(group__name="Rock")
+[<Person: Jim>, <Person: Jane>]
+
+# If the m2m field has specified a related_name, using that will work.
+>>> Person.objects.filter(custom__name="Rock")
+[<Person: Bob>, <Person: Jim>]
+
+# To query through the intermediary model in the reverse direction, we again
+# specify its model name (membership, in this case).
+>>> Person.objects.filter(membership__invite_reason="She was just awesome.")
+[<Person: Jane>]
+
+# Let's see all of the groups that Jane joined after 1 Jan 2005:
+>>> Group.objects.filter(membership__date_joined__gt=datetime(2005, 1, 1), membership__person =jane)
+[<Group: Rock>]
+
+# Queries also work in the reverse direction: Now let's see all of the people 
+# that have joined Rock since 1 Jan 2005:
+>>> Person.objects.filter(membership__date_joined__gt=datetime(2005, 1, 1), membership__group=rock)
+[<Person: Jim>, <Person: Jane>]
+
+# Conceivably, queries through membership could return correct, but non-unique
+# querysets.  To demonstrate this, we query for all people who have joined a 
+# group after 2004:
+>>> Person.objects.filter(membership__date_joined__gt=datetime(2004, 1, 1))
+[<Person: Jim>, <Person: Jim>, <Person: Jane>]
+
+# Jim showed up twice, because he joined two groups ('Rock', and 'Roll'):
+>>> [(m.person.name, m.group.name) for m in 
+... Membership.objects.filter(date_joined__gt=datetime(2004, 1, 1))]
+[(u'Jim', u'Rock'), (u'Jane', u'Rock'), (u'Jim', u'Roll')]
+
+# QuerySet's distinct() method can correct this problem.
+>>> Person.objects.filter(membership__date_joined__gt=datetime(2004, 1, 1)).distinct()
+[<Person: Jim>, <Person: Jane>]
+"""}

tests/regressiontests/m2m_through_regress/models.py

@@ +1 @@
+from django.db import models
+from datetime import datetime
+from django.contrib.auth.models import User
+
+# Forward declared intermediate model
+class Membership(models.Model):
+    person = models.ForeignKey('Person')
+    group = models.ForeignKey('Group')
+    date_joined = models.DateTimeField(default=datetime.now)
+    
+    def __unicode__(self):
+        return "%s is a member of %s" % (self.person.name, self.group.name)
+
+class UserMembership(models.Model):
+    user = models.ForeignKey(User)
+    group = models.ForeignKey('Group')
+    date_joined = models.DateTimeField(default=datetime.now)
+    
+    def __unicode__(self):
+        return "%s is a user and member of %s" % (self.user.username, self.group.name)
+
+class Person(models.Model):
+    name = models.CharField(max_length=128)
+
+    def __unicode__(self):
+        return self.name
+
+class Group(models.Model):
+    name = models.CharField(max_length=128)
+    # 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')
+>>> jim = Person.objects.create(name='Jim')
+
+>>> rock = Group.objects.create(name='Rock')
+>>> roll = Group.objects.create(name='Roll')
+
+>>> 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 
+>>> Membership.objects.create(person=bob, group=rock)
+<Membership: Bob is a member of Rock>
+
+>>> Membership.objects.create(person=bob, group=roll)
+<Membership: Bob is a member of Roll>
+
+>>> Membership.objects.create(person=jim, group=rock)
+<Membership: Jim is a member of Rock>
+
+>>> bob.group_set.all()
+[<Group: Rock>, <Group: Roll>]
+
+>>> roll.members.all()
+[<Person: Bob>]
+
+# Error messages use the model name, not repr of the class name
+>>> bob.group_set = []
+Traceback (most recent call last):
+...
+AttributeError: Cannot set values on a ManyToManyField which specifies an intermediary model.  Use Membership's Manager instead.
+
+>>> roll.members = []
+Traceback (most recent call last):
+...
+AttributeError: Cannot set values on a ManyToManyField which specifies an intermediary model.  Use Membership's Manager instead.
+
+>>> rock.members.create(name='Anne')
+Traceback (most recent call last):
+...
+AttributeError: Cannot use create() on a ManyToManyField which specifies an intermediary model.  Use Membership's Manager instead.
+
+>>> bob.group_set.create(name='Funk')
+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 
+# the current app (i.e., UserMembership) workds
+>>> UserMembership.objects.create(user=frank, group=rock)
+<UserMembership: frank is a user and member of Rock>
+
+>>> UserMembership.objects.create(user=frank, group=roll)
+<UserMembership: frank is a user and member of Roll>
+
+>>> UserMembership.objects.create(user=jane, group=rock)
+<UserMembership: jane is a user and member of Rock>
+
+>>> frank.group_set.all()
+[<Group: Rock>, <Group: Roll>]
+
+>>> roll.user_members.all()
+[<User: frank>]
+
+"""}

AUTHORS

@@ -154 +154 @@
-    Maciej Fijalkowski
-    Matthew Flanagan <http://wadofstuff.blogspot.com>
-    Eric Floehr <eric@intellovations.com>
+    Eric Florenzano <floguy@gmail.com>
-    Vincent Foley <vfoleybourgon@yahoo.ca>
-    Rudolph Froger <rfroger@estrate.nl>
-    Jorge Gajon <gajon@gajon.org>

docs/model-api.txt

@@ -945 +945 @@
-
-    =======================  ============================================================
-
+Extra fields on many-to-many relationships
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+When you're only dealing with mixing and matching pizzas and toppings, a
+standard ``ManyToManyField`` works great. However, sometimes you may want
+to associate data with the relationship between two models. 
+
+For example, consider the case of an application tracking the musical groups
+which musicians belong to. There is a many-to-many relationship between a person
+and the groups of which they are a member, so you could use a ManyToManyField
+to represent this relationship. However, there is a lot of detail about the
+membership that you might want to collect, such as the date at which the person
+joined the group.
+
+For these situations, Django allows you to specify the model that will be used
+to govern the many-to-many relationship. You can then put extra fields on the
+intermediate model. The intermediate model is associated with the 
+``ManyToManyField`` by using the ``through`` argument to point to the model
+that will act as an intermediary. For our musician example, the code would look
+something like this::
+
+    class Person(models.Model):
+        # ...
+        name = models.CharField(max_length=128)
+
+        def __unicode__(self):
+            return self.name
+
+    class Group(models.Model):
+        # ...
+        name = models.CharField(max_length=128)
+        members = models.ManyToManyField(Person, through='Membership')
+
+        def __unicode__(self):
+            return self.name
+
+    class Membership(models.Model):
+        person = models.ForeignKey(Person)
+        group = models.ForeignKey(Group)
+        date_joined = models.DateField()
+        invite_reason = models.CharField(max_length=64)
+
+When you set up the intermediary model, you must explicitly specify foreign 
+keys to the models in ManyToMany relation. This explicit declaration makes 
+it clear how two models are related.
+
+Now that you have set up your ``ManyToManyField`` to use your intermediary 
+model (Membership, in this case), you're ready to use the convenience methods
+provided by that ``ManyToManyField``.  Here's an example of how you can query
+for and use these models::
+    
+    >>> ringo = Person.objects.create(name="Ringo Starr")
+&nbs