from datetime import datetime from operator import attrgetter from django.test import TestCase from models import (Person, Group, Membership, CustomMembership, PersonSelfRefM2M, Friendship) class M2mThroughTests(TestCase): def setUp(self): self.bob = Person.objects.create(name='Bob') self.jim = Person.objects.create(name='Jim') self.jane = Person.objects.create(name='Jane') self.rock = Group.objects.create(name='Rock') self.roll = Group.objects.create(name='Roll') def test_m2m_through(self): # We start out by making sure that the Group 'rock' has no members. self.assertQuerysetEqual( self.rock.members.all(), [] ) # To make Jim a member of Group Rock, simply create a Membership object. m1 = Membership.objects.create(person=self.jim, group=self.rock) # We can do the same for Jane and Rock. m2 = Membership.objects.create(person=self.jane, group=self.rock) # Let's check to make sure that it worked. Jane and Jim should be members of Rock. self.assertQuerysetEqual( self.rock.members.all(), [ 'Jane', 'Jim' ], attrgetter("name") ) # Now we can add a bunch more Membership objects to test with. m3 = Membership.objects.create(person=self.bob, group=self.roll) m4 = Membership.objects.create(person=self.jim, group=self.roll) m5 = Membership.objects.create(person=self.jane, group=self.roll) # We can get Jim's Group membership as with any ForeignKey. self.assertQuerysetEqual( self.jim.group_set.all(), [ 'Rock', 'Roll' ], attrgetter("name") ) # Querying the intermediary model works like normal. self.assertEqual( repr(Membership.objects.get(person=self.jane, group=self.rock)), '' ) # It's not only get that works. Filter works like normal as well. self.assertQuerysetEqual( Membership.objects.filter(person=self.jim), [ '', '' ] ) self.rock.members.clear() # Now there will be no members of Rock. self.assertQuerysetEqual( self.rock.members.all(), [] ) def test_forward_descriptors(self): # Due to complications with adding via an intermediary model, # the add method is not provided. self.assertRaises(AttributeError, lambda: self.rock.members.add(self.bob)) # Create is also disabled as it suffers from the same problems as add. self.assertRaises(AttributeError, lambda: self.rock.members.create(name='Anne')) # Remove has similar complications, and is not provided either. self.assertRaises(AttributeError, lambda: self.rock.members.remove(self.jim)) m1 = Membership.objects.create(person=self.jim, group=self.rock) m2 = Membership.objects.create(person=self.jane, group=self.rock) # Here we back up the list of all members of Rock. backup = list(self.rock.members.all()) # ...and we verify that it has worked. self.assertEqual( [p.name for p in backup], ['Jane', 'Jim'] ) # The clear function should still work. self.rock.members.clear() # Now there will be no members of Rock. self.assertQuerysetEqual( self.rock.members.all(), [] ) # Assignment should not work with models specifying a through model for many of # the same reasons as adding. self.assertRaises(AttributeError, setattr, self.rock, "members", backup) # Let's re-save those instances that we've cleared. m1.save() m2.save() # Verifying that those instances were re-saved successfully. self.assertQuerysetEqual( self.rock.members.all(),[ 'Jane', 'Jim' ], attrgetter("name") ) def test_reverse_descriptors(self): # Due to complications with adding via an intermediary model, # the add method is not provided. self.assertRaises(AttributeError, lambda: self.bob.group_set.add(self.rock)) # Create is also disabled as it suffers from the same problems as add. self.assertRaises(AttributeError, lambda: self.bob.group_set.create(name="funk")) # Remove has similar complications, and is not provided either. self.assertRaises(AttributeError, lambda: self.jim.group_set.remove(self.rock)) m1 = Membership.objects.create(person=self.jim, group=self.rock) m2 = Membership.objects.create(person=self.jim, group=self.roll) # Here we back up the list of all of Jim's groups. backup = list(self.jim.group_set.all()) self.assertEqual( [g.name for g in backup], ['Rock', 'Roll'] ) # The clear function should still work. self.jim.group_set.clear() # Now Jim will be in no groups. self.assertQuerysetEqual( self.jim.group_set.all(), [] ) # Assignment should not work with models specifying a through model for many of # the same reasons as adding. self.assertRaises(AttributeError, setattr, self.jim, "group_set", backup) # Let's re-save those instances that we've cleared. m1.save() m2.save() # Verifying that those instances were re-saved successfully. self.assertQuerysetEqual( self.jim.group_set.all(),[ 'Rock', 'Roll' ], attrgetter("name") ) def test_custom_tests(self): # Let's see if we can query through our second relationship. self.assertQuerysetEqual( self.rock.custom_members.all(), [] ) # We can query in the opposite direction as well. self.assertQuerysetEqual( self.bob.custom.all(), [] ) cm1 = CustomMembership.objects.create(person=self.bob, group=self.rock) cm2 = CustomMembership.objects.create(person=self.jim, group=self.rock) # If we get the number of people in Rock, it should be both Bob and Jim. self.assertQuerysetEqual( self.rock.custom_members.all(),[ 'Bob', 'Jim' ], attrgetter("name") ) # Bob should only be in one custom group. self.assertQuerysetEqual( self.bob.custom.all(),[ 'Rock' ], attrgetter("name") ) # Let's make sure our new descriptors don't conflict with the FK related_name. self.assertQuerysetEqual( self.bob.custom_person_related_name.all(),[ '' ] ) def test_self_referential_tests(self): # Let's first create a person who has no friends. tony = PersonSelfRefM2M.objects.create(name="Tony") self.assertQuerysetEqual( tony.friends.all(), [] ) 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. self.assertQuerysetEqual( tony.friends.all(),[ 'Chris' ], attrgetter("name") ) # But we haven't established that Chris is Tony's Friend. self.assertQuerysetEqual( chris.friends.all(), [] ) 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. self.assertQuerysetEqual( chris.friends.all(),[ 'Tony' ], attrgetter("name") ) # Chris gets mad and wants to get rid of all of his friends. chris.friends.clear() # Now he should not have any more friends. self.assertQuerysetEqual( chris.friends.all(), [] ) # Since this isn't a symmetrical relation, Tony's friend link still exists. self.assertQuerysetEqual( tony.friends.all(),[ 'Chris' ], attrgetter("name") ) def test_query_tests(self): m1 = Membership.objects.create(person=self.jim, group=self.rock) m2 = Membership.objects.create(person=self.jane, group=self.rock) m3 = Membership.objects.create(person=self.bob, group=self.roll) m4 = Membership.objects.create(person=self.jim, group=self.roll) m5 = Membership.objects.create(person=self.jane, group=self.roll) m2.invite_reason = "She was just awesome." m2.date_joined = datetime(2006, 1, 1) m2.save() m3.date_joined = datetime(2004, 1, 1) m3.save() m5.date_joined = datetime(2004, 1, 1) m5.save() # We can query for the related model by using its attribute name (members, in # this case). self.assertQuerysetEqual( Group.objects.filter(members__name='Bob'),[ 'Roll' ], attrgetter("name") ) # To query through the intermediary model, we specify its model name. # In this case, membership. self.assertQuerysetEqual( Group.objects.filter(membership__invite_reason="She was just awesome."),[ 'Rock' ], attrgetter("name") ) # If we want to query in the reverse direction by the related model, use its # model name (group, in this case). self.assertQuerysetEqual( Person.objects.filter(group__name="Rock"),[ 'Jane', 'Jim' ], attrgetter("name") ) cm1 = CustomMembership.objects.create(person=self.bob, group=self.rock) cm2 = CustomMembership.objects.create(person=self.jim, group=self.rock) # If the m2m field has specified a related_name, using that will work. self.assertQuerysetEqual( Person.objects.filter(custom__name="Rock"),[ 'Bob', 'Jim' ], attrgetter("name") ) # To query through the intermediary model in the reverse direction, we again # specify its model name (membership, in this case). self.assertQuerysetEqual( Person.objects.filter(membership__invite_reason="She was just awesome."),[ 'Jane' ], attrgetter("name") ) # Let's see all of the groups that Jane joined after 1 Jan 2005: self.assertQuerysetEqual( Group.objects.filter(membership__date_joined__gt=datetime(2005, 1, 1), membership__person=self.jane),[ 'Rock' ], attrgetter("name") ) # Queries also work in the reverse direction: Now let's see all of the people # that have joined Rock since 1 Jan 2005: self.assertQuerysetEqual( Person.objects.filter(membership__date_joined__gt=datetime(2005, 1, 1), membership__group=self.rock),[ 'Jane', 'Jim' ], attrgetter("name") ) # 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: self.assertQuerysetEqual( Person.objects.filter(membership__date_joined__gt=datetime(2004, 1, 1)),[ 'Jane', 'Jim', 'Jim' ], attrgetter("name") ) # Jim showed up twice, because he joined two groups ('Rock', and 'Roll'): self.assertEqual( [(m.person.name, m.group.name) for m in Membership.objects.filter(date_joined__gt=datetime(2004, 1, 1))], [(u'Jane', u'Rock'), (u'Jim', u'Rock'), (u'Jim', u'Roll')] ) # QuerySet's distinct() method can correct this problem. self.assertQuerysetEqual( Person.objects.filter(membership__date_joined__gt=datetime(2004, 1, 1)).distinct(),[ 'Jane', 'Jim' ], attrgetter("name") )