Ticket #6095: 6095-qsrf.diff

File 6095-qsrf.diff, 26.3 KB (added by floguy, 16 years ago)

Updated the patch to apply to queryset-refactor. Currently two of my tests which pass on Trunk do not pass on qs-rf, and I'm not exactly sure why. Will have to wait to see more documentation on qs-rf before I can resolve.

  • AUTHORS 

    diff --git a/AUTHORS b/AUTHORS
index 9c28d73..5e2ce7a 100644
    a b answer newbie questions, and generally made Django that much better:  
    135135    Afonso Fernández Nogueira <fonzzo.django@gmail.com>
    136136    Matthew Flanagan <http://wadofstuff.blogspot.com>
    137137    Eric Floehr <eric@intellovations.com>
     138    Eric Florenzano <floguy@gmail.com>
    138139    Vincent Foley <vfoleybourgon@yahoo.ca>
    139140    Rudolph Froger <rfroger@estrate.nl>
    140141    Jorge Gajon <gajon@gajon.org>

  • django/core/management/sql.py 

    diff --git a/django/core/management/sql.py b/django/core/management/sql.py
index 9e606a7..079812a 100644
    a b def many_to_many_sql_for_model(model, style):  
    352352    qn = connection.ops.quote_name
    353353    inline_references = connection.features.inline_fk_references
    354354    for f in opts.local_many_to_many:
    355         if not isinstance(f.rel, generic.GenericRel):
     355        if not isinstance(f.rel, generic.GenericRel) and f.creates_table:
    356356            tablespace = f.db_tablespace or opts.db_tablespace
    357357            if tablespace and connection.features.supports_tablespaces and connection.features.autoindexes_primary_keys:
    358358                tablespace_sql = ' ' + connection.ops.tablespace_sql(tablespace, inline=True)

  • django/core/management/validation.py 

    diff --git a/django/core/management/validation.py b/django/core/management/validation.py
index cd1f84f..3036a36 100644
    a b def get_validation_errors(outfile, app=None):  
    104104                        if r.get_accessor_name() == rel_query_name:
    105105                            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))
    106106
     107        seen_intermediary_signatures = []
    107108        for i, f in enumerate(opts.local_many_to_many):
    108109            # Check to see if the related m2m field will clash with any
    109110            # existing fields, m2m fields, m2m related objects or related
    … … def get_validation_errors(outfile, app=None):  
    115116                if isinstance(f.rel.to, (str, unicode)):
    116117                    continue
    117118
     119            if hasattr(f.rel, 'through') and f.rel.through != None:
     120                intermediary_model = None
     121                for model in models.get_models():
     122                    if model._meta.module_name == f.rel.through.lower():
     123                        intermediary_model = model
     124                if intermediary_model == None:
     125                    e.add(opts, "%s has a manually-defined m2m relationship through a model (%s) which does not exist." % (f.name, f.rel.through))
     126                else:
     127                    signature = (f.rel.to, cls, intermediary_model)
     128                    if signature in seen_intermediary_signatures:
     129                        e.add(opts, "%s has two manually-defined m2m relationships through the same model (%s), which is not possible.  Please use a field on your intermediary model instead." % (cls._meta.object_name, intermediary_model._meta.object_name))
     130                    else:
     131                        seen_intermediary_signatures.append(signature)
     132                    seen_related_fk, seen_this_fk = False, False
     133                    for field in intermediary_model._meta.fields:
     134                        if field.rel:
     135                            if field.rel.to == f.rel.to:
     136                                seen_related_fk = True
     137                            elif field.rel.to == cls:
     138                                seen_this_fk = True
     139                    if not seen_related_fk or not seen_this_fk:
     140                        e.add(opts, "%s has a manually-defined m2m relationship through a model (%s) which does not have foreign keys to %s and %s" % (f.name, f.rel.through, f.rel.to._meta.object_name, cls._meta.object_name))
    118141            rel_opts = f.rel.to._meta
    119142            rel_name = RelatedObject(f.rel.to, cls, f).get_accessor_name()
    120143            rel_query_name = f.related_query_name()

  • django/db/models/fields/related.py 

    diff --git a/django/db/models/fields/related.py b/django/db/models/fields/related.py
index 818c8a9..f2ab3a1 100644
    a b from django.core import validators  
    1010from django import oldforms
    1111from django import newforms as forms
    1212from django.dispatch import dispatcher
     13from new import instancemethod
    1314
    1415try:
    1516    set
    … … class ForeignRelatedObjectsDescriptor(object):  
    306307            manager.clear()
    307308        manager.add(*value)
    308309
    309 def create_many_related_manager(superclass):
     310def create_many_related_manager(superclass, through=False):
    310311    """Creates a manager that subclasses 'superclass' (which is a Manager)
    311312    and adds behavior for many-to-many related objects."""
    312313    class ManyRelatedManager(superclass):
    … … def create_many_related_manager(superclass):  
    320321            self.join_table = join_table
    321322            self.source_col_name = source_col_name
    322323            self.target_col_name = target_col_name
     324            self.through = through
    323325            self._pk_val = self.instance._get_pk_val()
    324326            if self._pk_val is None:
    325327                raise ValueError("%r instance needs to have a primary key value before a many-to-many relationship can be used." % model)
    … … def create_many_related_manager(superclass):  
    327329        def get_query_set(self):
    328330            return superclass.get_query_set(self).filter(**(self.core_filters))
    329331
    330         def add(self, *objs):
    331             self._add_items(self.source_col_name, self.target_col_name, *objs)
    332 
    333             # If this is a symmetrical m2m relation to self, add the mirror entry in the m2m table
    334             if self.symmetrical:
    335                 self._add_items(self.target_col_name, self.source_col_name, *objs)
    336         add.alters_data = True
    337 
    338         def remove(self, *objs):
    339             self._remove_items(self.source_col_name, self.target_col_name, *objs)
    340 
    341             # If this is a symmetrical m2m relation to self, remove the mirror entry in the m2m table
    342             if self.symmetrical:
    343                 self._remove_items(self.target_col_name, self.source_col_name, *objs)
    344         remove.alters_data = True
    345 
    346332        def clear(self):
    347333            self._clear_items(self.source_col_name)
    348334
    … … def create_many_related_manager(superclass):  
    419405                [self._pk_val])
    420406            transaction.commit_unless_managed()
    421407
     408    def add(self, *objs):
     409        self._add_items(self.source_col_name, self.target_col_name, *objs)
     410
     411        # If this is a symmetrical m2m relation to self, add the mirror entry in the m2m table
     412        if self.symmetrical:
     413            self._add_items(self.target_col_name, self.source_col_name, *objs)
     414    add.alters_data = True
     415
     416    def remove(self, *objs):
     417        self._remove_items(self.source_col_name, self.target_col_name, *objs)
     418
     419        # If this is a symmetrical m2m relation to self, remove the mirror entry in the m2m table
     420        if self.symmetrical:
     421            self._remove_items(self.target_col_name, self.source_col_name, *objs)
     422    remove.alters_data = True
     423
     424    if not through:
     425        ManyRelatedManager.add = instancemethod(add, None, ManyRelatedManager)
     426        ManyRelatedManager.remove = instancemethod(remove, None, ManyRelatedManager)
     427
    422428    return ManyRelatedManager
    423429
    424430class ManyRelatedObjectsDescriptor(object):
    … … class ManyRelatedObjectsDescriptor(object):  
    439445        # model's default manager.
    440446        rel_model = self.related.model
    441447        superclass = rel_model._default_manager.__class__
    442         RelatedManager = create_many_related_manager(superclass)
     448        RelatedManager = create_many_related_manager(superclass, self.related.field.rel.through)
    443449
    444450        qn = connection.ops.quote_name
    445451        manager = RelatedManager(
    … … class ManyRelatedObjectsDescriptor(object):  
    458464        if instance is None:
    459465            raise AttributeError, "Manager must be accessed via instance"
    460466
     467        through = getattr(self.related.field.rel, 'through', None)
     468        if through is not None:
     469            raise AttributeError, "Cannot set values on a ManyToManyField which specifies a through model.  Use %s's Manager instead." % through
     470
    461471        manager = self.__get__(instance)
    462472        manager.clear()
    463473        manager.add(*value)
    … … class ReverseManyRelatedObjectsDescriptor(object):  
    480490        # model's default manager.
    481491        rel_model=self.field.rel.to
    482492        superclass = rel_model._default_manager.__class__
    483         RelatedManager = create_many_related_manager(superclass)
     493        RelatedManager = create_many_related_manager(superclass, self.field.rel.through)
    484494
    485495        qn = connection.ops.quote_name
    486496        manager = RelatedManager(
    … … class ReverseManyRelatedObjectsDescriptor(object):  
    499509        if instance is None:
    500510            raise AttributeError, "Manager must be accessed via instance"
    501511
     512        through = getattr(self.field.rel, 'through', None)
     513        if through is not None:
     514            raise AttributeError, "Cannot set values on a ManyToManyField which specifies a through model.  Use %s's Manager instead." % through
     515
    502516        manager = self.__get__(instance)
    503517        manager.clear()
    504518        manager.add(*value)
    … … class OneToOneRel(ManyToOneRel):  
    548562
    549563class ManyToManyRel(object):
    550564    def __init__(self, to, num_in_admin=0, related_name=None,
    551         filter_interface=None, limit_choices_to=None, raw_id_admin=False, symmetrical=True):
     565        filter_interface=None, limit_choices_to=None, raw_id_admin=False, symmetrical=True,
     566        through=None):
    552567        self.to = to
    553568        self.num_in_admin = num_in_admin
    554569        self.related_name = related_name
    … … class ManyToManyRel(object):  
    560575        self.raw_id_admin = raw_id_admin
    561576        self.symmetrical = symmetrical
    562577        self.multiple = True
     578        self.through = through
    563579
    564580        assert not (self.raw_id_admin and self.filter_interface), "ManyToManyRels may not use both raw_id_admin and filter_interface"
    565581
    … … class ManyToManyField(RelatedField, Field):  
    696712            filter_interface=kwargs.pop('filter_interface', None),
    697713            limit_choices_to=kwargs.pop('limit_choices_to', None),
    698714            raw_id_admin=kwargs.pop('raw_id_admin', False),
    699             symmetrical=kwargs.pop('symmetrical', True))
     715            symmetrical=kwargs.pop('symmetrical', True),
     716            through=kwargs.pop('through', None))
    700717        self.db_table = kwargs.pop('db_table', None)
     718        if kwargs['rel'].through:
     719            self.creates_table = False
     720            assert not self.db_table, "Cannot specify a db_table if an intermediary model is used."
     721        else:
     722            self.creates_table = True
    701723        if kwargs["rel"].raw_id_admin:
    702724            kwargs.setdefault("validator_list", []).append(self.isValidIDList)
    703725        Field.__init__(self, **kwargs)
    … … class ManyToManyField(RelatedField, Field):  
    720742
    721743    def _get_m2m_db_table(self, opts):
    722744        "Function that can be curried to provide the m2m table name for this relation"
    723         if self.db_table:
     745        if self.rel.through != None:
     746            return get_model(opts.app_label, self.rel.through)._meta.db_table
     747        elif self.db_table:
    724748            return self.db_table
    725749        else:
    726750            return '%s_%s' % (opts.db_table, self.name)
    … … class ManyToManyField(RelatedField, Field):  
    728752    def _get_m2m_column_name(self, related):
    729753        "Function that can be curried to provide the source column name for the m2m table"
    730754        # If this is an m2m relation to self, avoid the inevitable name clash
    731         if related.model == related.parent_model:
     755        if self.rel.through != None:
     756            field = related.model._meta.get_related_object(self.rel.through).field
     757            attname, column = field.get_attname_column()
     758            return column
     759        elif related.model == related.parent_model:
    732760            return 'from_' + related.model._meta.object_name.lower() + '_id'
    733761        else:
    734762            return related.model._meta.object_name.lower() + '_id'
    … … class ManyToManyField(RelatedField, Field):  
    736764    def _get_m2m_reverse_name(self, related):
    737765        "Function that can be curried to provide the related column name for the m2m table"
    738766        # If this is an m2m relation to self, avoid the inevitable name clash
    739         if related.model == related.parent_model:
     767        if self.rel.through != None:
     768            field = related.parent_model._meta.get_related_object(self.rel.through).field
     769            attname, column = field.get_attname_column()
     770            return column
     771        elif related.model == related.parent_model:
    740772            return 'to_' + related.parent_model._meta.object_name.lower() + '_id'
    741773        else:
    742774            return related.parent_model._meta.object_name.lower() + '_id'

  • django/db/models/options.py 

    diff --git a/django/db/models/options.py b/django/db/models/options.py
index 0796a3f..9a7855e 100644
    a b from django.db.models.related import RelatedObject  
    1010from django.db.models.fields.related import ManyToManyRel
    1111from django.db.models.fields import AutoField, FieldDoesNotExist
    1212from django.db.models.fields.proxy import OrderWrt
    13 from django.db.models.loading import get_models, app_cache_ready
     13from django.db.models.loading import get_models, get_model, app_cache_ready
    1414from django.db.models import Manager
    1515from django.utils.translation import activate, deactivate_all, get_language, string_concat
    1616from django.utils.encoding import force_unicode, smart_str
    … … class Options(object):  
    374374            follow = self.get_follow()
    375375        return [f for f in self.get_all_related_objects() if follow.get(f.name, None)]
    376376
     377    def get_related_object(self, from_model):
     378        "Gets the RelatedObject which links from from_model to this model."
     379        if isinstance(from_model, str):
     380            from_model = get_model(self.app_label, from_model)
     381        for related_object in self.get_all_related_objects():
     382            if related_object.model == from_model:
     383                return related_object
     384        return None
     385
    377386    def get_data_holders(self, follow=None):
    378387        if follow == None:
    379388            follow = self.get_follow()

  • tests/modeltests/invalid_models/models.py 

    diff --git a/tests/modeltests/invalid_models/models.py b/tests/modeltests/invalid_models/models.py
index 8a480a2..2523f29 100644
    a b class MissingRelations(models.Model):  
    112112    rel1 = models.ForeignKey("Rel1")
    113113    rel2 = models.ManyToManyField("Rel2")
    114114
     115class MissingManualM2MModel(models.Model):
     116    name = models.CharField(max_length=5)
     117    missing_m2m = models.ManyToManyField(Model, through="MissingM2MModel")
     118   
     119class Person(models.Model):
     120    name = models.CharField(max_length=5)
     121
     122class Group(models.Model):
     123    name = models.CharField(max_length=5)
     124    primary = models.ManyToManyField(Person, through="Membership", related_name="primary")
     125    secondary = models.ManyToManyField(Person, through="Membership", related_name="secondary")
     126
     127class GroupTwo(models.Model):
     128    name = models.CharField(max_length=5)
     129    primary = models.ManyToManyField(Person, through="Membership")
     130    secondary = models.ManyToManyField(Group, through="MembershipMissingFK")
     131
     132class Membership(models.Model):
     133    person = models.ForeignKey(Person)
     134    group = models.ForeignKey(Group)
     135    not_default_or_null = models.CharField(max_length=5)
     136
     137class MembershipMissingFK(models.Model):
     138    person = models.ForeignKey(Person)
     139
    115140model_errors = """invalid_models.fielderrors: "charfield": CharFields require a "max_length" attribute.
    116141invalid_models.fielderrors: "decimalfield": DecimalFields require a "decimal_places" attribute.
    117142invalid_models.fielderrors: "decimalfield": DecimalFields require a "max_digits" attribute.
    … … invalid_models.selfclashm2m: Reverse query name for m2m field 'm2m_3' clashes wi  
    197222invalid_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'.
    198223invalid_models.missingrelations: 'rel2' has m2m relation with model Rel2, which has not been installed
    199224invalid_models.missingrelations: 'rel1' has relation with model Rel1, which has not been installed
     225invalid_models.group: Group has two manually-defined m2m relationships through the same model (Membership), which is not possible.  Please use a field on your intermediary model instead.
     226invalid_models.missingmanualm2mmodel: missing_m2m has a manually-defined m2m relationship through a model (MissingM2MModel) which does not exist.
     227invalid_models.grouptwo: primary has a manually-defined m2m relationship through a model (Membership) which does not have foreign keys to Person and GroupTwo
     228invalid_models.grouptwo: secondary has a manually-defined m2m relationship through a model (MembershipMissingFK) which does not have foreign keys to Group and GroupTwo
    200229"""

  • new file tests/modeltests/m2m_manual/models.py 

    diff --git a/tests/modeltests/m2m_manual/__init__.py b/tests/modeltests/m2m_manual/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/modeltests/m2m_manual/models.py b/tests/modeltests/m2m_manual/models.py
new file mode 100644
index 0000000..c79d0c4
    - +  
     1from django.db import models
     2from datetime import datetime
     3
     4# M2M described on one of the models
     5class Person(models.Model):
     6    name = models.CharField(max_length=128)
     7
     8    def __unicode__(self):
     9        return self.name
     10
     11class Group(models.Model):
     12    name = models.CharField(max_length=128)
     13    members = models.ManyToManyField(Person, through='Membership')
     14    custom_members = models.ManyToManyField(Person, through='CustomMembership', related_name="custom")
     15    nodefaultsnonulls = models.ManyToManyField(Person, through='TestNoDefaultsOrNulls', related_name="testnodefaultsnonulls")
     16   
     17    def __unicode__(self):
     18        return self.name
     19
     20class Membership(models.Model):
     21    person = models.ForeignKey(Person)
     22    group = models.ForeignKey(Group)
     23    date_joined = models.DateTimeField(default=datetime.now)
     24    invite_reason = models.CharField(max_length=64, null=True)
     25   
     26    def __unicode__(self):
     27        return "%s is a member of %s" % (self.person.name, self.group.name)
     28
     29class CustomMembership(models.Model):
     30    person = models.ForeignKey(Person, db_column="custom_person_column", related_name="custom_person_related_name")
     31    group = models.ForeignKey(Group)
     32    weird_fk = models.ForeignKey(Membership, null=True)
     33    date_joined = models.DateTimeField(default=datetime.now)
     34   
     35    def __unicode__(self):
     36        return "%s is a member of %s" % (self.person.name, self.group.name)
     37   
     38    class Meta:
     39        db_table = "test_table"
     40
     41class TestNoDefaultsOrNulls(models.Model):
     42    person = models.ForeignKey(Person)
     43    group = models.ForeignKey(Group)
     44    nodefaultnonull = models.CharField(max_length=5)
     45
     46__test__ = {'API_TESTS':"""
     47>>> from datetime import datetime
     48
     49### Creation and Saving Tests ###
     50
     51>>> bob = Person.objects.create(name = 'Bob')
     52>>> jim = Person.objects.create(name = 'Jim')
     53>>> jane = Person.objects.create(name = 'Jane')
     54>>> rock = Group.objects.create(name = 'Rock')
     55>>> roll = Group.objects.create(name = 'Roll')
     56
     57# We start out by making sure that the Group 'rock' has no members.
     58>>> rock.members.all()
     59[]
     60
     61# To make Jim a member of Group Rock, simply create a Membership object.
     62>>> m1 = Membership.objects.create(person = jim, group = rock)
     63
     64# We can do the same for Jane and Rock.
     65>>> m2 = Membership.objects.create(person = jane, group = rock)
     66
     67# Let's check to make sure that it worked.  Jane and Jim should be members of Rock.
     68>>> rock.members.all()
     69[<Person: Jim>, <Person: Jane>]
     70
     71# Now we can add a bunch more Membership objects to test with.
     72>>> m3 = Membership.objects.create(person = bob, group = roll)
     73>>> m4 = Membership.objects.create(person = jim, group = roll)
     74>>> m5 = Membership.objects.create(person = jane, group = roll)
     75
     76# We can get Jim's Group membership as with any ForeignKey.
     77>>> jim.group_set.all()
     78[<Group: Rock>, <Group: Roll>]
     79
     80# Querying the intermediary model works like normal. 
     81# In this case we get Jane's membership to Rock.
     82>>> m = Membership.objects.get(person = jane, group = rock)
     83>>> m
     84<Membership: Jane is a member of Rock>
     85
     86# Now we set some date_joined dates for further testing.
     87>>> m2.invite_reason = "She was just awesome."
     88>>> m2.date_joined = datetime(2006, 1, 1)
     89>>> m2.save()
     90
     91>>> m5.date_joined = datetime(2004, 1, 1)
     92>>> m5.save()
     93
     94>>> m3.date_joined = datetime(2004, 1, 1)
     95>>> m3.save()
     96
     97# It's not only get that works.  Filter works like normal as well.
     98>>> Membership.objects.filter(person = jim)
     99[<Membership: Jim is a member of Rock>, <Membership: Jim is a member of Roll>]
     100
     101
     102### Forward Descriptors Tests ###
     103
     104# Due to complications with adding via an intermediary model, the add method is
     105# not provided.
     106>>> rock.members.add(bob)
     107Traceback (most recent call last):
     108...
     109AttributeError: 'ManyRelatedManager' object has no attribute 'add'
     110
     111# Remove has similar complications, and is not provided either.
     112>>> rock.members.remove(jim)
     113Traceback (most recent call last):
     114...
     115AttributeError: 'ManyRelatedManager' object has no attribute 'remove'
     116
     117# Here we back up the list of all members of Rock.
     118>>> backup = list(rock.members.all())
     119
     120# ...and we verify that it has worked.
     121>>> backup
     122[<Person: Jim>, <Person: Jane>]
     123
     124# The clear function should still work.
     125>>> rock.members.clear()
     126
     127# Now there will be no members of Rock.
     128>>> rock.members.all()
     129[]
     130
     131# Assignment should not work with models specifying a through model for many of
     132# the same reasons as adding.
     133>>> rock.members = backup
     134Traceback (most recent call last):
     135...
     136AttributeError: Cannot set values on a ManyToManyField which specifies a through model.  Use Membership's Manager instead.
     137
     138# Let's re-save those instances that we've cleared.
     139>>> m1.save()
     140>>> m2.save()
     141
     142# Verifying that those instances were re-saved successfully.
     143>>> rock.members.all()
     144[<Person: Jim>, <Person: Jane>]
     145
     146
     147### Reverse Descriptors Tests ###
     148
     149# Due to complications with adding via an intermediary model, the add method is
     150# not provided.
     151>>> bob.group_set.add(rock)
     152Traceback (most recent call last):
     153...
     154AttributeError: 'ManyRelatedManager' object has no attribute 'add'
     155
     156# Remove has similar complications, and is not provided either.
     157>>> jim.group_set.remove(rock)
     158Traceback (most recent call last):
     159...
     160AttributeError: 'ManyRelatedManager' object has no attribute 'remove'
     161
     162# Here we back up the list of all of Jim's groups.
     163>>> backup = list(jim.group_set.all())
     164>>> backup
     165[<Group: Rock>, <Group: Roll>]
     166
     167# The clear function should still work.
     168>>> jim.group_set.clear()
     169
     170# Now Jim will be in no groups.
     171>>> jim.group_set.all()
     172[]
     173
     174# Assignment should not work with models specifying a through model for many of
     175# the same reasons as adding.
     176>>> jim.group_set = backup
     177Traceback (most recent call last):
     178...
     179AttributeError: Cannot set values on a ManyToManyField which specifies a through model.  Use Membership's Manager instead.
     180
     181# Let's re-save those instances that we've cleared.
     182>>> m1.save()
     183>>> m4.save()
     184
     185# Verifying that those instances were re-saved successfully.
     186>>> jim.group_set.all()
     187[<Group: Rock>, <Group: Roll>]
     188
     189### Custom Tests ###
     190
     191# Let's see if we can query through our second relationship.
     192>>> rock.custom_members.all()
     193[]
     194
     195# We can query in the opposite direction as well.
     196>>> bob.custom.all()
     197[]
     198
     199# Let's create some membership objects in this custom relationship.
     200>>> cm1 = CustomMembership.objects.create(person = bob, group = rock)
     201>>> cm2 = CustomMembership.objects.create(person = jim, group = rock)
     202
     203# If we get the number of people in Rock, it should be both Bob and Jim.
     204>>> rock.custom_members.all()
     205[<Person: Bob>, <Person: Jim>]
     206
     207# Bob should only be in one custom group.
     208>>> bob.custom.all()
     209[<Group: Rock>]
     210
     211# Let's make sure our new descriptors don't conflict with the FK related_name.
     212>>> bob.custom_person_related_name.all()
     213[<CustomMembership: Bob is a member of Rock>]
     214
     215### QUERY TESTS ###
     216
     217# We can query for the related model by using its attribute name (members, in
     218# this case).
     219>>> Group.objects.filter(members__name='Bob')
     220[<Group: Roll>]
     221
     222# To query through the intermediary model, we specify its model name.
     223# In this case, membership.
     224>>> Group.objects.filter(membership__invite_reason = "She was just awesome.")
     225[<Group: Rock>]
     226
     227# If we want to query in the reverse direction by the related model, use its
     228# model name (group, in this case).
     229>>> Person.objects.filter(group__name="Rock")
     230[<Person: Jim>, <Person: Jane>]
     231
     232# If the m2m field has specified a related_name, using that will work.
     233>>> Person.objects.filter(custom__name="Rock")
     234[<Person: Bob>, <Person: Jim>]
     235
     236# To query through the intermediary model in the reverse direction, we again
     237# specify its model name (membership, in this case).
     238>>> Person.objects.filter(membership__invite_reason = "She was just awesome.")
     239[<Person: Jane>]
     240
     241# Let's see all of the groups that Jane joined after 1 Jan 2005:
     242>>> Group.objects.filter(membership__date_joined__gt = datetime(2005, 1, 1),
     243... membership__person = jane)
     244[<Group: Rock>]
     245
     246# Queries also work in the reverse direction: Now let's see all of the people
     247# that have joined Rock since 1 Jan 2005:
     248>>> Person.objects.filter(membership__date_joined__gt = datetime(2005, 1, 1),
     249... membership__group = rock)
     250[<Person: Jim>, <Person: Jane>]
     251
     252# Conceivably, queries through membership could return correct, but non-unique
     253# querysets.  To demonstrate this, we query for all people who have joined a
     254# group after 2004:
     255>>> Person.objects.filter(membership__date_joined__gt = datetime(2004, 1, 1))
     256[<Person: Jim>, <Person: Jim>, <Person: Jane>]
     257
     258# Jim showed up twice, because he joined two groups ('Rock', and 'Roll'):
     259>>> [(m.person.name, m.group.name) for m in
     260... Membership.objects.filter(date_joined__gt = datetime(2004, 1, 1))]
     261[(u'Jim', u'Rock'), (u'Jane', u'Rock'), (u'Jim', u'Roll')]
     262
     263# QuerySet's distinct() method can correct this problem.
     264>>> Person.objects.filter(membership__date_joined__gt = datetime(2004, 1, 1)).distinct()
     265[<Person: Jim>, <Person: Jane>]
     266"""}
     267 No newline at end of file
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