def test_self_relation(self):
"""
#24513 - Modifying an object pointing to itself would cause it to be
rendered twice and thus breaking its related M2M through objects.
"""
class A(models.Model):
to_a = models.ManyToManyField('something.A', symmetrical=False)
class Meta:
app_label = "something"
def get_model_a(state):
return [
mod for mod in state.apps.get_models()
if mod._meta.model_name == 'a'
][0]
project_state = ProjectState()
project_state.add_model((ModelState.from_model(A)))
self.assertEqual(len(get_model_a(project_state)._meta.related_objects),
1)
old_state = project_state.clone()
operation = AlterField(model_name="a",
name="to_a",
field=models.ManyToManyField("something.A",
symmetrical=False,
blank=True))
# At this point the model would be rendered twice causing its related
# M2M through objects to point to an old copy and thus breaking their
# attribute lookup.
operation.state_forwards("something", project_state)
model_a_old = get_model_a(old_state)
model_a_new = get_model_a(project_state)
self.assertIsNot(model_a_old, model_a_new)
# Tests that the old model's _meta is still consistent
field_to_a_old = model_a_old._meta.get_field("to_a")
self.assertEqual(field_to_a_old.m2m_field_name(), "from_a")
self.assertEqual(field_to_a_old.m2m_reverse_field_name(), "to_a")
self.assertIs(field_to_a_old.related_model, model_a_old)
self.assertIs(
field_to_a_old.remote_field.through._meta.get_field(
'to_a').related_model, model_a_old)
self.assertIs(
field_to_a_old.remote_field.through._meta.get_field(
'from_a').related_model, model_a_old)
# Tests that the new model's _meta is still consistent
field_to_a_new = model_a_new._meta.get_field("to_a")
self.assertEqual(field_to_a_new.m2m_field_name(), "from_a")
self.assertEqual(field_to_a_new.m2m_reverse_field_name(), "to_a")
self.assertIs(field_to_a_new.related_model, model_a_new)
self.assertIs(
field_to_a_new.remote_field.through._meta.get_field(
'to_a').related_model, model_a_new)
self.assertIs(
field_to_a_new.remote_field.through._meta.get_field(
'from_a').related_model, model_a_new)
def test_self_relation(self):
"""
#24513 - Modifying an object pointing to itself would cause it to be
rendered twice and thus breaking its related M2M through objects.
"""
class A(models.Model):
to_a = models.ManyToManyField('something.A', symmetrical=False)
class Meta:
app_label = "something"
def get_model_a(state):
return [mod for mod in state.apps.get_models() if mod._meta.model_name == 'a'][0]
project_state = ProjectState()
project_state.add_model((ModelState.from_model(A)))
self.assertEqual(len(get_model_a(project_state)._meta.related_objects), 1)
old_state = project_state.clone()
operation = AlterField(
model_name="a",
name="to_a",
field=models.ManyToManyField("something.A", symmetrical=False, blank=True)
)
# At this point the model would be rendered twice causing its related
# M2M through objects to point to an old copy and thus breaking their
# attribute lookup.
operation.state_forwards("something", project_state)
model_a_old = get_model_a(old_state)
model_a_new = get_model_a(project_state)
self.assertIsNot(model_a_old, model_a_new)
# Tests that the old model's _meta is still consistent
field_to_a_old = model_a_old._meta.get_field("to_a")
self.assertEqual(field_to_a_old.m2m_field_name(), "from_a")
self.assertEqual(field_to_a_old.m2m_reverse_field_name(), "to_a")
self.assertIs(field_to_a_old.related_model, model_a_old)
self.assertIs(field_to_a_old.remote_field.through._meta.get_field('to_a').related_model, model_a_old)
self.assertIs(field_to_a_old.remote_field.through._meta.get_field('from_a').related_model, model_a_old)
# Tests that the new model's _meta is still consistent
field_to_a_new = model_a_new._meta.get_field("to_a")
self.assertEqual(field_to_a_new.m2m_field_name(), "from_a")
self.assertEqual(field_to_a_new.m2m_reverse_field_name(), "to_a")
self.assertIs(field_to_a_new.related_model, model_a_new)
self.assertIs(field_to_a_new.remote_field.through._meta.get_field('to_a').related_model, model_a_new)
self.assertIs(field_to_a_new.remote_field.through._meta.get_field('from_a').related_model, model_a_new)