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