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Ticket #6095: 6095-nfadmin.diff

File 6095-nfadmin.diff, 26.8 kB (added by floguy, 9 months ago)

Updated patch for newforms-admin, with the added bonus of fixing the integration problem with the admin. Now when a ManyToManyField? specifies an intermediary model, it does not display the field in the admin.

  • a/AUTHORS

    old new  
    134134    Afonso Fernández Nogueira <fonzzo.django@gmail.com> 
    135135    Matthew Flanagan <http://wadofstuff.blogspot.com> 
    136136    Eric Floehr <eric@intellovations.com> 
     137    Eric Florenzano <floguy@gmail.com> 
    137138    Vincent Foley <vfoleybourgon@yahoo.ca> 
    138139    Rudolph Froger <rfroger@estrate.nl> 
    139140    Jorge Gajon <gajon@gajon.org> 
  • a/django/contrib/admin/options.py

    old new  
    172172                kwargs['widget'] = widgets.ForeignKeyRawIdWidget(db_field.rel) 
    173173            else: 
    174174                if isinstance(db_field, models.ManyToManyField): 
    175                     if db_field.name in self.raw_id_fields: 
     175                    # If it uses an intermediary model, don't show field in admin. 
     176                    if db_field.rel.through != None: 
     177                        return None 
     178                    elif db_field.name in self.raw_id_fields: 
    176179                        kwargs['widget'] = widgets.ManyToManyRawIdWidget(db_field.rel) 
    177180                        kwargs['help_text'] = '' 
    178181                    elif db_field.name in (self.filter_vertical + self.filter_horizontal): 
  • a/django/core/management/sql.py

    old new  
    352352    qn = connection.ops.quote_name 
    353353    inline_references = connection.features.inline_fk_references 
    354354    for f in opts.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) 
  • a/django/core/management/validation.py

    old new  
    102102                        if r.get_accessor_name() == rel_query_name: 
    103103                            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)) 
    104104 
     105        seen_intermediary_signatures = [] 
     106 
    105107        for i, f in enumerate(opts.many_to_many): 
    106108            # Check to see if the related m2m field will clash with any 
    107109            # existing fields, m2m fields, m2m related objects or related objects 
     
    111113                # so skip the next section 
    112114                if isinstance(f.rel.to, (str, unicode)): 
    113115                    continue 
     116            if hasattr(f.rel, 'through') and f.rel.through != None: 
     117                intermediary_model = None 
     118                for model in models.get_models(): 
     119                    if model._meta.module_name == f.rel.through.lower(): 
     120                        intermediary_model = model 
     121                if intermediary_model == None: 
     122                    e.add(opts, "%s has a manually-defined m2m relationship through a model (%s) which does not exist." % (f.name, f.rel.through)) 
     123                else: 
     124                    signature = (f.rel.to, cls, intermediary_model) 
     125                    if signature in seen_intermediary_signatures: 
     126                        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)) 
     127                    else: 
     128                        seen_intermediary_signatures.append(signature) 
     129                    seen_related_fk, seen_this_fk = False, False 
     130                    for field in intermediary_model._meta.fields: 
     131                        if field.rel: 
     132                            if field.rel.to == f.rel.to: 
     133                                seen_related_fk = True 
     134                            elif field.rel.to == cls: 
     135                                seen_this_fk = True 
     136                    if not seen_related_fk or not seen_this_fk: 
     137                        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)) 
    114138 
    115139            rel_opts = f.rel.to._meta 
    116140            rel_name = RelatedObject(f.rel.to, cls, f).get_accessor_name() 
  • a/django/db/models/fields/related.py

    old new  
    1010from django import oldforms 
    1111from django import newforms as forms 
    1212from django.dispatch import dispatcher 
     13from new import instancemethod 
    1314 
    1415try: 
    1516    set 
     
    262263            manager.clear() 
    263264        manager.add(*value) 
    264265 
    265 def create_many_related_manager(superclass): 
     266def create_many_related_manager(superclass, through=False): 
    266267    """Creates a manager that subclasses 'superclass' (which is a Manager) 
    267268    and adds behavior for many-to-many related objects.""" 
    268269    class ManyRelatedManager(superclass): 
     
    276277            self.join_table = join_table 
    277278            self.source_col_name = source_col_name 
    278279            self.target_col_name = target_col_name 
     280            self.through = through 
    279281            self._pk_val = self.instance._get_pk_val() 
    280282            if self._pk_val is None: 
    281283                raise ValueError("%r instance needs to have a primary key value before a many-to-many relationship can be used." % model) 
     
    283285        def get_query_set(self): 
    284286            return superclass.get_query_set(self).filter(**(self.core_filters)) 
    285287 
    286         def add(self, *objs): 
    287             self._add_items(self.source_col_name, self.target_col_name, *objs) 
    288  
    289             # If this is a symmetrical m2m relation to self, add the mirror entry in the m2m table 
    290             if self.symmetrical: 
    291                 self._add_items(self.target_col_name, self.source_col_name, *objs) 
    292         add.alters_data = True 
    293  
    294         def remove(self, *objs): 
    295             self._remove_items(self.source_col_name, self.target_col_name, *objs) 
    296  
    297             # If this is a symmetrical m2m relation to self, remove the mirror entry in the m2m table 
    298             if self.symmetrical: 
    299                 self._remove_items(self.target_col_name, self.source_col_name, *objs) 
    300         remove.alters_data = True 
    301  
    302288        def clear(self): 
    303289            self._clear_items(self.source_col_name) 
    304290 
     
    375361                [self._pk_val]) 
    376362            transaction.commit_unless_managed() 
    377363 
     364    def add(self, *objs): 
     365        self._add_items(self.source_col_name, self.target_col_name, *objs) 
     366        # If this is a symmetrical m2m relation to self, add the mirror entry in the m2m table 
     367        if self.symmetrical: 
     368            self._add_items(self.target_col_name, self.source_col_name, *objs) 
     369    add.alters_data = True 
     370 
     371    def remove(self, *objs): 
     372        self._remove_items(self.source_col_name, self.target_col_name, *objs) 
     373        # If this is a symmetrical m2m relation to self, remove the mirror entry in the m2m table 
     374        if self.symmetrical: 
     375            self._remove_items(self.target_col_name, self.source_col_name, *objs) 
     376    remove.alters_data = True 
     377 
     378    if not through: 
     379        ManyRelatedManager.add = instancemethod(add, None, ManyRelatedManager) 
     380        ManyRelatedManager.remove = instancemethod(remove, None, ManyRelatedManager) 
     381 
    378382    return ManyRelatedManager 
    379383 
    380384class ManyRelatedObjectsDescriptor(object): 
     
    395399        # model's default manager. 
    396400        rel_model = self.related.model 
    397401        superclass = rel_model._default_manager.__class__ 
    398         RelatedManager = create_many_related_manager(superclass
     402        RelatedManager = create_many_related_manager(superclass, self.related.field.rel.through
    399403 
    400404        qn = connection.ops.quote_name 
    401405        manager = RelatedManager( 
     
    414418        if instance is None: 
    415419            raise AttributeError, "Manager must be accessed via instance" 
    416420 
     421        through = getattr(self.related.field.rel, 'through', None) 
     422        if through: 
     423            raise AttributeError, "Cannot set values on a ManyToManyField which specifies a through model.  Use %s's Manager instead." % through 
     424         
    417425        manager = self.__get__(instance) 
    418426        manager.clear() 
    419427        manager.add(*value) 
     
    436444        # model's default manager. 
    437445        rel_model=self.field.rel.to 
    438446        superclass = rel_model._default_manager.__class__ 
    439         RelatedManager = create_many_related_manager(superclass
     447        RelatedManager = create_many_related_manager(superclass, self.field.rel.through
    440448 
    441449        qn = connection.ops.quote_name 
    442450        manager = RelatedManager( 
     
    455463        if instance is None: 
    456464            raise AttributeError, "Manager must be accessed via instance" 
    457465 
     466        through = getattr(self.field.rel, 'through', None) 
     467        if through: 
     468            raise AttributeError, "Cannot set values on a ManyToManyField which specifies a through model.  Use %s's Manager instead." % through 
     469 
    458470        manager = self.__get__(instance) 
    459471        manager.clear() 
    460472        manager.add(*value) 
     
    633645            num_in_admin=kwargs.pop('num_in_admin', 0), 
    634646            related_name=kwargs.pop('related_name', None), 
    635647            limit_choices_to=kwargs.pop('limit_choices_to', None), 
    636             symmetrical=kwargs.pop('symmetrical', True)) 
     648            symmetrical=kwargs.pop('symmetrical', True), 
     649            through=kwargs.pop('through', None)) 
    637650        self.db_table = kwargs.pop('db_table', None) 
     651        if kwargs['rel'].through: 
     652            self.creates_table = False 
     653            assert not self.db_table, "Cannot specify a db_table if an intermediary model is used." 
     654        else: 
     655            self.creates_table = True  
    638656        Field.__init__(self, **kwargs) 
    639657 
    640658        msg = ugettext_lazy('Hold down "Control", or "Command" on a Mac, to select more than one.') 
     
    649667 
    650668    def _get_m2m_db_table(self, opts): 
    651669        "Function that can be curried to provide the m2m table name for this relation" 
    652         if self.db_table: 
     670        if self.rel.through != None:  
     671            return get_model(opts.app_label, self.rel.through)._meta.db_table 
     672        elif self.db_table: 
    653673            return self.db_table 
    654674        else: 
    655675            return '%s_%s' % (opts.db_table, self.name) 
     
    657677    def _get_m2m_column_name(self, related): 
    658678        "Function that can be curried to provide the source column name for the m2m table" 
    659679        # If this is an m2m relation to self, avoid the inevitable name clash 
    660         if related.model == related.parent_model: 
     680        if self.rel.through != None: 
     681            field = related.model._meta.get_related_object(self.rel.through).field 
     682            attname, column = field.get_attname_column()  
     683            return column  
     684        elif related.model == related.parent_model: 
    661685            return 'from_' + related.model._meta.object_name.lower() + '_id' 
    662686        else: 
    663687            return related.model._meta.object_name.lower() + '_id' 
     
    665689    def _get_m2m_reverse_name(self, related): 
    666690        "Function that can be curried to provide the related column name for the m2m table" 
    667691        # If this is an m2m relation to self, avoid the inevitable name clash 
    668         if related.model == related.parent_model: 
     692        if self.rel.through != None: 
     693            field = related.parent_model._meta.get_related_object(self.rel.through).field 
     694            attname, column = field.get_attname_column()  
     695            return column 
     696        elif related.model == related.parent_model: 
    669697            return 'to_' + related.parent_model._meta.object_name.lower() + '_id' 
    670698        else: 
    671699            return related.parent_model._meta.object_name.lower() + '_id' 
     
    780808 
    781809class ManyToManyRel(object): 
    782810    def __init__(self, to, num_in_admin=0, related_name=None, 
    783         limit_choices_to=None, symmetrical=True): 
     811        limit_choices_to=None, symmetrical=True, through=None): 
    784812        self.to = to 
    785813        self.num_in_admin = num_in_admin 
    786814        self.related_name = related_name 
     
    790818        self.edit_inline = False 
    791819        self.symmetrical = symmetrical 
    792820        self.multiple = True 
     821        self.through = through  
  • a/django/db/models/options.py

    old new  
    22from django.db.models.related import RelatedObject 
    33from django.db.models.fields.related import ManyToManyRel 
    44from django.db.models.fields import AutoField, FieldDoesNotExist 
    5 from django.db.models.loading import get_models, app_cache_ready 
     5from django.db.models.loading import get_models, get_model, app_cache_ready 
    66from django.db.models.query import orderlist2sql 
    77from django.utils.translation import activate, deactivate_all, get_language, string_concat 
    88from django.utils.encoding import force_unicode, smart_str 
     
    161161            follow = self.get_follow() 
    162162        return [f for f in self.get_all_related_objects() if follow.get(f.name, None)] 
    163163 
     164    def get_related_object(self, from_model): 
     165        "Gets the RelatedObject which links from from_model to this model." 
     166        if isinstance(from_model, str): 
     167            from_model = get_model(self.app_label, from_model) 
     168        for related_object in self.get_all_related_objects(): 
     169            if related_object.model == from_model: 
     170                return related_object 
     171        return None 
     172 
    164173    def get_data_holders(self, follow=None): 
    165174        if follow == None: 
    166175            follow = self.get_follow() 
  • a/tests/modeltests/invalid_models/models.py

    old new  
    110110class MissingRelations(models.Model): 
    111111    rel1 = models.ForeignKey("Rel1") 
    112112    rel2 = models.ManyToManyField("Rel2") 
     113     
     114class MissingManualM2MModel(models.Model): 
     115    name = models.CharField(max_length=5) 
     116    missing_m2m = models.ManyToManyField(Model, through="MissingM2MModel") 
     117     
     118class Person(models.Model): 
     119    name = models.CharField(max_length=5) 
     120 
     121class Group(models.Model): 
     122    name = models.CharField(max_length=5) 
     123    primary = models.ManyToManyField(Person, through="Membership", related_name="primary") 
     124    secondary = models.ManyToManyField(Person, through="Membership", related_name="secondary") 
     125 
     126class GroupTwo(models.Model): 
     127    name = models.CharField(max_length=5) 
     128    primary = models.ManyToManyField(Person, through="Membership") 
     129    secondary = models.ManyToManyField(Group, through="MembershipMissingFK") 
     130 
     131class Membership(models.Model): 
     132    person = models.ForeignKey(Person) 
     133    group = models.ForeignKey(Group) 
     134    not_default_or_null = models.CharField(max_length=5) 
     135 
     136class MembershipMissingFK(models.Model): 
     137    person = models.ForeignKey(Person) 
    113138 
    114139model_errors = """invalid_models.fielderrors: "charfield": CharFields require a "max_length" attribute. 
    115140invalid_models.fielderrors: "decimalfield": DecimalFields require a "decimal_places" attribute. 
     
    195220invalid_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'. 
    196221invalid_models.missingrelations: 'rel2' has m2m relation with model Rel2, which has not been installed 
    197222invalid_models.missingrelations: 'rel1' has relation with model Rel1, which has not been installed 
     223invalid_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. 
     224invalid_models.missingmanualm2mmodel: missing_m2m has a manually-defined m2m relationship through a model (MissingM2MModel) which does not exist. 
     225invalid_models.grouptwo: primary has a manually-defined m2m relationship through a model (Membership) which does not have foreign keys to Person and GroupTwo 
     226invalid_models.grouptwo: secondary has a manually-defined m2m relationship through a model (MembershipMissingFK) which does not have foreign keys to Group and GroupTwo 
    198227""" 
  • /dev/null

    old new  
     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"""}