Django

Code

Ticket #6095: 6095-nfadmin.3.diff

File 6095-nfadmin.3.diff, 26.7 kB (added by brosner, 7 months ago)

updated to r7500 of nfa

  • a/AUTHORS

    old new  
    144144    Afonso Fernández Nogueira <fonzzo.django@gmail.com> 
    145145    Matthew Flanagan <http://wadofstuff.blogspot.com> 
    146146    Eric Floehr <eric@intellovations.com> 
     147    Eric Florenzano <floguy@gmail.com> 
    147148    Vincent Foley <vfoleybourgon@yahoo.ca> 
    148149    Rudolph Froger <rfroger@estrate.nl> 
    149150    Jorge Gajon <gajon@gajon.org> 
  • a/django/contrib/admin/options.py

    old new  
    174174                kwargs['widget'] = widgets.ForeignKeyRawIdWidget(db_field.rel) 
    175175            else: 
    176176                if isinstance(db_field, models.ManyToManyField): 
    177                     if db_field.name in self.raw_id_fields: 
     177                    # If it uses an intermediary model, don't show field in admin. 
     178                    if db_field.rel.through != None: 
     179                        return None 
     180                    elif db_field.name in self.raw_id_fields: 
    178181                        kwargs['widget'] = widgets.ManyToManyRawIdWidget(db_field.rel) 
    179182                        kwargs['help_text'] = '' 
    180183                    elif db_field.name in (self.filter_vertical + self.filter_horizontal): 
  • a/django/core/management/sql.py

    old new  
    354354    qn = connection.ops.quote_name 
    355355    inline_references = connection.features.inline_fk_references 
    356356    for f in opts.local_many_to_many: 
    357         if not isinstance(f.rel, generic.GenericRel)
     357        if not isinstance(f.rel, generic.GenericRel) and f.creates_table
    358358            tablespace = f.db_tablespace or opts.db_tablespace 
    359359            if tablespace and connection.features.supports_tablespaces and connection.features.autoindexes_primary_keys: 
    360360                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 = [] 
    105106        for i, f in enumerate(opts.local_many_to_many): 
    106107            # Check to see if the related m2m field will clash with any 
    107108            # existing fields, m2m fields, m2m related objects or related 
     
    112113                # so skip the next section 
    113114                if isinstance(f.rel.to, (str, unicode)): 
    114115                    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)) 
    115138 
    116139            rel_opts = f.rel.to._meta 
    117140            rel_name = RelatedObject(f.rel.to, cls, f).get_accessor_name() 
  • a/django/db/models/fields/related.py

    old new  
    310310            manager.clear() 
    311311        manager.add(*value) 
    312312 
    313 def create_many_related_manager(superclass): 
     313def create_many_related_manager(superclass, through=False): 
    314314    """Creates a manager that subclasses 'superclass' (which is a Manager) 
    315315    and adds behavior for many-to-many related objects.""" 
    316316    class ManyRelatedManager(superclass): 
     
    324324            self.join_table = join_table 
    325325            self.source_col_name = source_col_name 
    326326            self.target_col_name = target_col_name 
     327            self.through = through 
    327328            self._pk_val = self.instance._get_pk_val() 
    328329            if self._pk_val is None: 
    329330                raise ValueError("%r instance needs to have a primary key value before a many-to-many relationship can be used." % model) 
     
    333334 
    334335        def add(self, *objs): 
    335336            self._add_items(self.source_col_name, self.target_col_name, *objs) 
    336  
    337337            # If this is a symmetrical m2m relation to self, add the mirror entry in the m2m table 
    338338            if self.symmetrical: 
    339339                self._add_items(self.target_col_name, self.source_col_name, *objs) 
    340340        add.alters_data = True 
    341  
     341     
    342342        def remove(self, *objs): 
    343343            self._remove_items(self.source_col_name, self.target_col_name, *objs) 
    344  
    345344            # If this is a symmetrical m2m relation to self, remove the mirror entry in the m2m table 
    346345            if self.symmetrical: 
    347346                self._remove_items(self.target_col_name, self.source_col_name, *objs) 
     
    356355        clear.alters_data = True 
    357356 
    358357        def create(self, **kwargs): 
     358            if through: 
     359                raise AttributeError, "'ManyRelatedManager' object has no attribute 'create'" 
    359360            new_obj = self.model(**kwargs) 
    360361            new_obj.save() 
    361362            self.add(new_obj) 
     
    423424                [self._pk_val]) 
    424425            transaction.commit_unless_managed() 
    425426 
     427    # If it's an intermediary model, detach the add, remove, and create methods 
     428    # from this ManyRelatedManager. 
     429    if through: 
     430        del ManyRelatedManager.add 
     431        del ManyRelatedManager.remove 
     432 
    426433    return ManyRelatedManager 
    427434 
    428435class ManyRelatedObjectsDescriptor(object): 
     
    443450        # model's default manager. 
    444451        rel_model = self.related.model 
    445452        superclass = rel_model._default_manager.__class__ 
    446         RelatedManager = create_many_related_manager(superclass
     453        RelatedManager = create_many_related_manager(superclass, self.related.field.rel.through
    447454 
    448455        qn = connection.ops.quote_name 
    449456        manager = RelatedManager( 
     
    462469        if instance is None: 
    463470            raise AttributeError, "Manager must be accessed via instance" 
    464471 
     472        through = getattr(self.related.field.rel, 'through', None) 
     473        if through: 
     474            raise AttributeError, "Cannot set values on a ManyToManyField which specifies a through model.  Use %s's Manager instead." % through 
     475         
    465476        manager = self.__get__(instance) 
    466477        manager.clear() 
    467478        manager.add(*value) 
     
    484495        # model's default manager. 
    485496        rel_model=self.field.rel.to 
    486497        superclass = rel_model._default_manager.__class__ 
    487         RelatedManager = create_many_related_manager(superclass
     498        RelatedManager = create_many_related_manager(superclass, self.field.rel.through
    488499 
    489500        qn = connection.ops.quote_name 
    490501        manager = RelatedManager( 
     
    503514        if instance is None: 
    504515            raise AttributeError, "Manager must be accessed via instance" 
    505516 
     517        through = getattr(self.field.rel, 'through', None) 
     518        if through: 
     519            raise AttributeError, "Cannot set values on a ManyToManyField which specifies a through model.  Use %s's Manager instead." % through 
     520 
    506521        manager = self.__get__(instance) 
    507522        manager.clear() 
    508523        manager.add(*value) 
     
    554569 
    555570class ManyToManyRel(object): 
    556571    def __init__(self, to, num_in_admin=0, related_name=None, 
    557         limit_choices_to=None, symmetrical=True): 
     572        limit_choices_to=None, symmetrical=True, through=None): 
    558573        self.to = to 
    559574        self.num_in_admin = num_in_admin 
    560575        self.related_name = related_name 
     
    564579        self.edit_inline = False 
    565580        self.symmetrical = symmetrical 
    566581        self.multiple = True 
     582        self.through = through 
    567583 
    568584class ForeignKey(RelatedField, Field): 
    569585    empty_strings_allowed = False 
     
    695711            num_in_admin=kwargs.pop('num_in_admin', 0), 
    696712            related_name=kwargs.pop('related_name', None), 
    697713            limit_choices_to=kwargs.pop('limit_choices_to', None), 
    698             symmetrical=kwargs.pop('symmetrical', True)) 
     714            symmetrical=kwargs.pop('symmetrical', True), 
     715            through=kwargs.pop('through', None)) 
    699716        self.db_table = kwargs.pop('db_table', None) 
     717        if kwargs['rel'].through: 
     718            self.creates_table = False 
     719            assert not self.db_table, "Cannot specify a db_table if an intermediary model is used." 
     720        else: 
     721            self.creates_table = True  
    700722        Field.__init__(self, **kwargs) 
    701723 
    702724        msg = ugettext_lazy('Hold down "Control", or "Command" on a Mac, to select more than one.') 
     
    711733 
    712734    def _get_m2m_db_table(self, opts): 
    713735        "Function that can be curried to provide the m2m table name for this relation" 
    714         if self.db_table: 
     736        if self.rel.through != None:  
     737            return get_model(opts.app_label, self.rel.through)._meta.db_table 
     738        elif self.db_table: 
    715739            return self.db_table 
    716740        else: 
    717741            return '%s_%s' % (opts.db_table, self.name) 
     
    719743    def _get_m2m_column_name(self, related): 
    720744        "Function that can be curried to provide the source column name for the m2m table" 
    721745        # If this is an m2m relation to self, avoid the inevitable name clash 
    722         if related.model == related.parent_model: 
     746        if self.rel.through != None: 
     747            field = related.model._meta.get_related_object(self.rel.through).field 
     748            attname, column = field.get_attname_column()  
     749            return column  
     750        elif related.model == related.parent_model: 
    723751            return 'from_' + related.model._meta.object_name.lower() + '_id' 
    724752        else: 
    725753            return related.model._meta.object_name.lower() + '_id' 
     
    727755    def _get_m2m_reverse_name(self, related): 
    728756        "Function that can be curried to provide the related column name for the m2m table" 
    729757        # If this is an m2m relation to self, avoid the inevitable name clash 
    730         if related.model == related.parent_model: 
     758        if self.rel.through != None: 
     759            field = related.parent_model._meta.get_related_object(self.rel.through).field 
     760            attname, column = field.get_attname_column()  
     761            return column 
     762        elif related.model == related.parent_model: 
    731763            return 'to_' + related.parent_model._meta.object_name.lower() + '_id' 
    732764        else: 
    733765            return related.parent_model._meta.object_name.lower() + '_id' 
  • a/django/db/models/options.py

    old new  
    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.utils.translation import activate, deactivate_all, get_language, string_concat 
    1515from django.utils.encoding import force_unicode, smart_str 
    1616from django.utils.datastructures import SortedDict 
     
    373373            follow = self.get_follow() 
    374374        return [f for f in self.get_all_related_objects() if follow.get(f.name, None)] 
    375375 
     376    def get_related_object(self, from_model): 
     377        "Gets the RelatedObject which links from from_model to this model." 
     378        if isinstance(from_model, str): 
     379            from_model = get_model(self.app_label, from_model) 
     380        for related_object in self.get_all_related_objects(): 
     381            if related_object.model == from_model: 
     382                return related_object 
     383        return None 
     384 
    376385    def get_data_holders(self, follow=None): 
    377386        if follow == None: 
    378387            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  
  • /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>>> rock.members.create(name = 'Anne') 
     112Traceback (most recent call last): 
     113... 
     114AttributeError: 'ManyRelatedManager' object has no attribute 'create' 
     115 
     116# Remove has similar complications, and is not provided either. 
     117>>> rock.members.remove(jim) 
     118Traceback (most recent call last): 
     119... 
     120AttributeError: 'ManyRelatedManager' object has no attribute 'remove' 
     121 
     122# Here we back up the list of all members of Rock. 
     123>>> backup = list(rock.members.all()) 
     124 
     125# ...and we verify that it has worked. 
     126>>> backup 
     127[<Person: Jim>, <Person: Jane>] 
     128 
     129# The clear function should still work. 
     130>>> rock.members.clear() 
     131 
     132# Now there will be no members of Rock. 
     133>>> rock.members.all() 
     134[] 
     135 
     136# Assignment should not work with models specifying a through model for many of 
     137# the same reasons as adding. 
     138>>> rock.members = backup 
     139Traceback (most recent call last): 
     140... 
     141AttributeError: Cannot set values on a ManyToManyField which specifies a through model.  Use Membership's Manager instead. 
     142 
     143# Let's re-save those instances that we've cleared. 
     144>>> m1.save() 
     145>>> m2.save() 
     146 
     147# Verifying that those instances were re-saved successfully. 
     148>>> rock.members.all() 
     149[<Person: Jim>, <Person: Jane>] 
     150 
     151 
     152### Reverse Descriptors Tests ### 
     153 
     154# Due to complications with adding via an intermediary model, the add method is 
     155# not provided. 
     156>>> bob.group_set.add(rock) 
     157Traceback (most recent call last): 
     158... 
     159AttributeError: 'ManyRelatedManager' object has no attribute 'add' 
     160 
     161# Create is another method that should not work correctly, as it suffers from 
     162# the same problems as add. 
     163>>> bob.group_set.create(name = 'Funk') 
     164Traceback (most recent call last): 
     165... 
     166AttributeError: 'ManyRelatedManager' object has no attribute 'create' 
     167 
     168# Remove has similar complications, and is not provided either. 
     169>>> jim.group_set.remove(rock) 
     170Traceback (most recent call last): 
     171... 
     172AttributeError: 'ManyRelatedManager' object has no attribute 'remove' 
     173 
     174# Here we back up the list of all of Jim's groups. 
     175>>> backup = list(jim.group_set.all()) 
     176>>> backup 
     177[<Group: Rock>, <Group: Roll>] 
     178 
     179# The clear function should still work. 
     180>>> jim.group_set.clear() 
     181 
     182# Now Jim will be in no groups. 
     183>>> jim.group_set.all() 
     184[] 
     185 
     186# Assignment should not work with models specifying a through model for many of 
     187# the same reasons as adding. 
     188>>> jim.group_set = backup 
     189Traceback (most recent call last): 
     190... 
     191AttributeError: Cannot set values on a ManyToManyField which specifies a through model.  Use Membership's Manager instead. 
     192 
     193# Let's re-save those instances that we've cleared. 
     194>>> m1.save() 
     195>>> m4.save() 
     196 
     197# Verifying that those instances were re-saved successfully. 
     198>>> jim.group_set.all() 
     199[<Group: Rock>, <Group: Roll>] 
     200 
     201### Custom Tests ### 
     202 
     203# Let's see if we can query through our second relationship. 
     204>>> rock.custom_members.all() 
     205[] 
     206 
     207# We can query in the opposite direction as well. 
     208>>> bob.custom.all() 
     209[] 
     210 
     211# Let's create some membership objects in this custom relationship. 
     212>>> cm1 = CustomMembership.objects.create(person = bob, group = rock) 
     213>>> cm2 = CustomMembership.objects.create(person = jim, group = rock) 
     214 
     215# If we get the number of people in Rock, it should be both Bob and Jim. 
     216>>> rock.custom_members.all() 
     217[<Person: Bob>, <Person: Jim>] 
     218 
     219# Bob should only be in one custom group. 
     220>>> bob.custom.all() 
     221[<Group: Rock>] 
     222 
     223# Let's make sure our new descriptors don't conflict with the FK related_name. 
     224>>> bob.custom_person_related_name.all() 
     225[<CustomMembership: Bob is a member of Rock>] 
     226 
     227### QUERY TESTS ### 
     228 
     229# We can query for the related model by using its attribute name (members, in  
     230# this case). 
     231>>> Group.objects.filter(members__name='Bob') 
     232[<Group: Roll>] 
     233 
     234# To query through the intermediary model, we specify its model name. 
     235# In this case, membership. 
     236>>> Group.objects.filter(membership__invite_reason = "She was just awesome.") 
     237[<Group: Rock>] 
     238 
     239# If we want to query in the reverse direction by the related model, use its 
     240# model name (group, in this case). 
     241>>> Person.objects.filter(group__name="Rock") 
     242[<Person: Jim>, <Person: Jane>] 
     243 
     244# If the m2m field has specified a related_name, using that will work. 
     245>>> Person.objects.filter(custom__name="Rock") 
     246[<Person: Bob>, <Person: Jim>] 
     247 
     248# To query through the intermediary model in the reverse direction, we again 
     249# specify its model name (membership, in this case). 
     250>>> Person.objects.filter(membership__invite_reason = "She was just awesome.") 
     251[<Person: Jane>] 
     252 
     253# Let's see all of the groups that Jane joined after 1 Jan 2005: 
     254>>> Group.objects.filter(membership__date_joined__gt = datetime(2005, 1, 1),  
     255... membership__person = jane) 
     256[<Group: Rock>] 
     257 
     258# Queries also work in the reverse direction: Now let's see all of the people  
     259# that have joined Rock since 1 Jan 2005: 
     260>>> Person.objects.filter(membership__date_joined__gt = datetime(2005, 1, 1),  
     261... membership__group = rock) 
     262[<Person: Jim>, <Person: Jane>] 
     263 
     264# Conceivably, queries through membership could return correct, but non-unique 
     265# querysets.  To demonstrate this, we query for all people who have joined a  
     266# group after 2004: 
     267>>> Person.objects.filter(membership__date_joined__gt = datetime(2004, 1, 1)) 
     268[<Person: Jim>, <Person: Jim>, <Person: Jane>] 
     269 
     270# Jim showed up twice, because he joined two groups ('Rock', and 'Roll'): 
     271>>> [(m.person.name, m.group.name) for m in  
     272... Membership.objects.filter(date_joined__gt = datetime(2004, 1, 1))] 
     273[(u'Jim', u'Rock'), (u'Jane', u'Rock'), (u'Jim', u'Roll')] 
     274 
     275# QuerySet's distinct() method can correct this problem. 
     276>>> Person.objects.filter(membership__date_joined__gt = datetime(2004, 1, 1)).distinct() 
     277[<Person: Jim>, <Person: Jane>] 
     278"""}