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"""
Testing signals emitted on changing m2m relations.
"""
from django.db import models
from django.test import TestCase
from .models import Car, Part, Person, SportsCar
class ManyToManySignalsTest(TestCase):
@classmethod
def setUpTestData(cls):
cls.vw = Car.objects.create(name='VW')
cls.bmw = Car.objects.create(name='BMW')
cls.toyota = Car.objects.create(name='Toyota')
cls.wheelset = Part.objects.create(name='Wheelset')
cls.doors = Part.objects.create(name='Doors')
cls.engine = Part.objects.create(name='Engine')
cls.airbag = Part.objects.create(name='Airbag')
cls.sunroof = Part.objects.create(name='Sunroof')
cls.alice = Person.objects.create(name='Alice')
cls.bob = Person.objects.create(name='Bob')
cls.chuck = Person.objects.create(name='Chuck')
cls.daisy = Person.objects.create(name='Daisy')
def setUp(self):
self.m2m_changed_messages = []
def m2m_changed_signal_receiver(self, signal, sender, **kwargs):
message = {
'instance': kwargs['instance'],
'action': kwargs['action'],
'reverse': kwargs['reverse'],
'model': kwargs['model'],
}
if kwargs['pk_set']:
message['objects'] = list(
kwargs['model'].objects.filter(pk__in=kwargs['pk_set'])
)
self.m2m_changed_messages.append(message)
def tearDown(self):
# disconnect all signal handlers
models.signals.m2m_changed.disconnect(
self.m2m_changed_signal_receiver, Car.default_parts.through
)
models.signals.m2m_changed.disconnect(
self.m2m_changed_signal_receiver, Car.optional_parts.through
)
models.signals.m2m_changed.disconnect(
self.m2m_changed_signal_receiver, Person.fans.through
)
models.signals.m2m_changed.disconnect(
self.m2m_changed_signal_receiver, Person.friends.through
)
def _initialize_signal_car(self, add_default_parts_before_set_signal=False):
""" Install a listener on the two m2m relations. """
models.signals.m2m_changed.connect(
self.m2m_changed_signal_receiver, Car.optional_parts.through
)
if add_default_parts_before_set_signal:
# adding a default part to our car - no signal listener installed
self.vw.default_parts.add(self.sunroof)
models.signals.m2m_changed.connect(
self.m2m_changed_signal_receiver, Car.default_parts.through
)
def test_pk_set_on_repeated_add_remove(self):
"""
m2m_changed is always fired, even for repeated calls to the same
method, but the behavior of pk_sets differs by action.
- For signals related to `add()`, only PKs that will actually be
inserted are sent.
- For `remove()` all PKs are sent, even if they will not affect the DB.
"""
pk_sets_sent = []
def handler(signal, sender, **kwargs):
if kwargs['action'] in ['pre_add', 'pre_remove']:
pk_sets_sent.append(kwargs['pk_set'])
models.signals.m2m_changed.connect(handler, Car.default_parts.through)
self.vw.default_parts.add(self.wheelset)
self.vw.default_parts.add(self.wheelset)
self.vw.default_parts.remove(self.wheelset)
self.vw.default_parts.remove(self.wheelset)
expected_pk_sets = [{self.wheelset.pk}, set(), {self.wheelset.pk}, {self.wheelset.pk}]
self.assertEqual(pk_sets_sent, expected_pk_sets)
models.signals.m2m_changed.disconnect(handler, Car.default_parts.through)
def test_m2m_relations_add_remove_clear(self):
expected_messages = []
self._initialize_signal_car(add_default_parts_before_set_signal=True)
self.vw.default_parts.add(self.wheelset, self.doors, self.engine)
expected_messages.append({
'instance': self.vw,
'action': 'pre_add',
'reverse': False,
'model': Part,
'objects': [self.doors, self.engine, self.wheelset],
})
expected_messages.append({
'instance': self.vw,
'action': 'post_add',
'reverse': False,
'model': Part,
'objects': [self.doors, self.engine, self.wheelset],
})
self.assertEqual(self.m2m_changed_messages, expected_messages)
# give the BMW and Toyota some doors as well
self.doors.car_set.add(self.bmw, self.toyota)
expected_messages.append({
'instance': self.doors,
'action': 'pre_add',
'reverse': True,
'model': Car,
'objects': [self.bmw, self.toyota],
})
expected_messages.append({
'instance': self.doors,
'action': 'post_add',
'reverse': True,
'model': Car,
'objects': [self.bmw, self.toyota],
})
self.assertEqual(self.m2m_changed_messages, expected_messages)
def test_m2m_relations_signals_remove_relation(self):
self._initialize_signal_car()
# remove the engine from the self.vw and the airbag (which is not set
# but is returned)
self.vw.default_parts.remove(self.engine, self.airbag)
self.assertEqual(self.m2m_changed_messages, [
{
'instance': self.vw,
'action': 'pre_remove',
'reverse': False,
'model': Part,
'objects': [self.airbag, self.engine],
}, {
'instance': self.vw,
'action': 'post_remove',
'reverse': False,
'model': Part,
'objects': [self.airbag, self.engine],
}
])
def test_m2m_relations_signals_give_the_self_vw_some_optional_parts(self):
expected_messages = []
self._initialize_signal_car()
# give the self.vw some optional parts (second relation to same model)
self.vw.optional_parts.add(self.airbag, self.sunroof)
expected_messages.append({
'instance': self.vw,
'action': 'pre_add',
'reverse': False,
'model': Part,
'objects': [self.airbag, self.sunroof],
})
expected_messages.append({
'instance': self.vw,
'action': 'post_add',
'reverse': False,
'model': Part,
'objects': [self.airbag, self.sunroof],
})
self.assertEqual(self.m2m_changed_messages, expected_messages)
# add airbag to all the cars (even though the self.vw already has one)
self.airbag.cars_optional.add(self.vw, self.bmw, self.toyota)
expected_messages.append({
'instance': self.airbag,
'action': 'pre_add',
'reverse': True,
'model': Car,
'objects': [self.bmw, self.toyota],
})
expected_messages.append({
'instance': self.airbag,
'action': 'post_add',
'reverse': True,
'model': Car,
'objects': [self.bmw, self.toyota],
})
self.assertEqual(self.m2m_changed_messages, expected_messages)
def test_m2m_relations_signals_reverse_relation_with_custom_related_name(self):
self._initialize_signal_car()
# remove airbag from the self.vw (reverse relation with custom
# related_name)
self.airbag.cars_optional.remove(self.vw)
self.assertEqual(self.m2m_changed_messages, [
{
'instance': self.airbag,
'action': 'pre_remove',
'reverse': True,
'model': Car,
'objects': [self.vw],
}, {
'instance': self.airbag,
'action': 'post_remove',
'reverse': True,
'model': Car,
'objects': [self.vw],
}
])
def test_m2m_relations_signals_clear_all_parts_of_the_self_vw(self):
self._initialize_signal_car()
# clear all parts of the self.vw
self.vw.default_parts.clear()
self.assertEqual(self.m2m_changed_messages, [
{
'instance': self.vw,
'action': 'pre_clear',
'reverse': False,
'model': Part,
}, {
'instance': self.vw,
'action': 'post_clear',
'reverse': False,
'model': Part,
}
])
def test_m2m_relations_signals_all_the_doors_off_of_cars(self):
self._initialize_signal_car()
# take all the doors off of cars
self.doors.car_set.clear()
self.assertEqual(self.m2m_changed_messages, [
{
'instance': self.doors,
'action': 'pre_clear',
'reverse': True,
'model': Car,
}, {
'instance': self.doors,
'action': 'post_clear',
'reverse': True,
'model': Car,
}
])
def test_m2m_relations_signals_reverse_relation(self):
self._initialize_signal_car()
# take all the airbags off of cars (clear reverse relation with custom
# related_name)
self.airbag.cars_optional.clear()
self.assertEqual(self.m2m_changed_messages, [
{
'instance': self.airbag,
'action': 'pre_clear',
'reverse': True,
'model': Car,
}, {
'instance': self.airbag,
'action': 'post_clear',
'reverse': True,
'model': Car,
}
])
def test_m2m_relations_signals_alternative_ways(self):
expected_messages = []
self._initialize_signal_car()
# alternative ways of setting relation:
self.vw.default_parts.create(name='Windows')
p6 = Part.objects.get(name='Windows')
expected_messages.append({
'instance': self.vw,
'action': 'pre_add',
'reverse': False,
'model': Part,
'objects': [p6],
})
expected_messages.append({
'instance': self.vw,
'action': 'post_add',
'reverse': False,
'model': Part,
'objects': [p6],
})
self.assertEqual(self.m2m_changed_messages, expected_messages)
# direct assignment clears the set first, then adds
self.vw.default_parts.set([self.wheelset, self.doors, self.engine])
expected_messages.append({
'instance': self.vw,
'action': 'pre_remove',
'reverse': False,
'model': Part,
'objects': [p6],
})
expected_messages.append({
'instance': self.vw,
'action': 'post_remove',
'reverse': False,
'model': Part,
'objects': [p6],
})
expected_messages.append({
'instance': self.vw,
'action': 'pre_add',
'reverse': False,
'model': Part,
'objects': [self.doors, self.engine, self.wheelset],
})
expected_messages.append({
'instance': self.vw,
'action': 'post_add',
'reverse': False,
'model': Part,
'objects': [self.doors, self.engine, self.wheelset],
})
self.assertEqual(self.m2m_changed_messages, expected_messages)
def test_m2m_relations_signals_clearing_removing(self):
expected_messages = []
self._initialize_signal_car(add_default_parts_before_set_signal=True)
# set by clearing.
self.vw.default_parts.set([self.wheelset, self.doors, self.engine], clear=True)
expected_messages.append({
'instance': self.vw,
'action': 'pre_clear',
'reverse': False,
'model': Part,
})
expected_messages.append({
'instance': self.vw,
'action': 'post_clear',
'reverse': False,
'model': Part,
})
expected_messages.append({
'instance': self.vw,
'action': 'pre_add',
'reverse': False,
'model': Part,
'objects': [self.doors, self.engine, self.wheelset],
})
expected_messages.append({
'instance': self.vw,
'action': 'post_add',
'reverse': False,
'model': Part,
'objects': [self.doors, self.engine, self.wheelset],
})
self.assertEqual(self.m2m_changed_messages, expected_messages)
# set by only removing what's necessary.
self.vw.default_parts.set([self.wheelset, self.doors], clear=False)
expected_messages.append({
'instance': self.vw,
'action': 'pre_remove',
'reverse': False,
'model': Part,
'objects': [self.engine],
})
expected_messages.append({
'instance': self.vw,
'action': 'post_remove',
'reverse': False,
'model': Part,
'objects': [self.engine],
})
self.assertEqual(self.m2m_changed_messages, expected_messages)
def test_m2m_relations_signals_when_inheritance(self):
expected_messages = []
self._initialize_signal_car(add_default_parts_before_set_signal=True)
# Signals still work when model inheritance is involved
c4 = SportsCar.objects.create(name='Bugatti', price='1000000')
c4b = Car.objects.get(name='Bugatti')
c4.default_parts.set([self.doors])
expected_messages.append({
'instance': c4,
'action': 'pre_add',
'reverse': False,
'model': Part,
'objects': [self.doors],
})
expected_messages.append({
'instance': c4,
'action': 'post_add',
'reverse': False,
'model': Part,
'objects': [self.doors],
})
self.assertEqual(self.m2m_changed_messages, expected_messages)
self.engine.car_set.add(c4)
expected_messages.append({
'instance': self.engine,
'action': 'pre_add',
'reverse': True,
'model': Car,
'objects': [c4b],
})
expected_messages.append({
'instance': self.engine,
'action': 'post_add',
'reverse': True,
'model': Car,
'objects': [c4b],
})
self.assertEqual(self.m2m_changed_messages, expected_messages)
def _initialize_signal_person(self):
# Install a listener on the two m2m relations.
models.signals.m2m_changed.connect(
self.m2m_changed_signal_receiver, Person.fans.through
)
models.signals.m2m_changed.connect(
self.m2m_changed_signal_receiver, Person.friends.through
)
def test_m2m_relations_with_self_add_friends(self):
self._initialize_signal_person()
self.alice.friends.set([self.bob, self.chuck])
self.assertEqual(self.m2m_changed_messages, [
{
'instance': self.alice,
'action': 'pre_add',
'reverse': False,
'model': Person,
'objects': [self.bob, self.chuck],
}, {
'instance': self.alice,
'action': 'post_add',
'reverse': False,
'model': Person,
'objects': [self.bob, self.chuck],
}
])
def test_m2m_relations_with_self_add_fan(self):
self._initialize_signal_person()
self.alice.fans.set([self.daisy])
self.assertEqual(self.m2m_changed_messages, [
{
'instance': self.alice,
'action': 'pre_add',
'reverse': False,
'model': Person,
'objects': [self.daisy],
}, {
'instance': self.alice,
'action': 'post_add',
'reverse': False,
'model': Person,
'objects': [self.daisy],
}
])
def test_m2m_relations_with_self_add_idols(self):
self._initialize_signal_person()
self.chuck.idols.set([self.alice, self.bob])
self.assertEqual(self.m2m_changed_messages, [
{
'instance': self.chuck,
'action': 'pre_add',
'reverse': True,
'model': Person,
'objects': [self.alice, self.bob],
}, {
'instance': self.chuck,
'action': 'post_add',
'reverse': True,
'model': Person,
'objects': [self.alice, self.bob],
}
])
|
