handle cascade delete
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Arthur
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5cdd9c6cdd
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@ -241,13 +241,14 @@ class CircuitGroupAssignment(CustomFieldsMixin, ExportTemplatesMixin, TagsMixin,
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return reverse('circuits:circuitgroupassignment', args=[self.pk])
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def _set_circuit_termination(circuit, field_name, value):
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def _set_circuit_terminations(circuit, fields):
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"""
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Set or clear a Circuit's cached `termination_a`/`termination_z` field, recording the change.
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Set or clear a Circuit's cached `termination_a`/`termination_z` fields, recording the change.
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"""
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circuit.snapshot()
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setattr(circuit, field_name, value)
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circuit.save(update_fields=[field_name, 'last_updated'])
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for field_name, value in fields.items():
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setattr(circuit, field_name, value)
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circuit.save(update_fields=[*fields, 'last_updated'])
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class CircuitTermination(
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@ -416,28 +417,34 @@ class CircuitTermination(
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pk=self._orig_circuit_id, **{old_termination_name: self.pk}
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).first()
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if circuit is not None:
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_set_circuit_termination(circuit, old_termination_name, None)
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_set_circuit_terminations(circuit, {old_termination_name: None})
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# Update the cache if this is a new termination or circuit/term_side changed
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if is_new or circuit_changed or term_side_changed:
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# Update the new circuit's termination reference
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termination_name = f'termination_{self.term_side.lower()}'
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_set_circuit_termination(Circuit.objects.get(pk=self.circuit_id), termination_name, self)
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_set_circuit_terminations(Circuit.objects.get(pk=self.circuit_id), {termination_name: self})
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# Update cached values for subsequent saves
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self._orig_circuit_id = self.circuit_id
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self._orig_term_side = self.term_side
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def delete(self, *args, **kwargs):
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# Clear the circuit's reference here; on_delete=SET_NULL is not change-logged
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termination_name = f'termination_{self.term_side.lower()}'
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circuit = Circuit.objects.filter(pk=self.circuit_id, **{termination_name: self.pk}).first()
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if circuit is not None:
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_set_circuit_termination(circuit, termination_name, None)
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@classmethod
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def clear_cached_references(cls, instances, collector):
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# Called by CustomCollector ahead of the DELETE, for explicit and cascaded deletions alike
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pks = {instance.pk for instance in instances}
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doomed_circuits = {circuit.pk for circuit in collector.data.get(Circuit, ())}
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return super().delete(*args, **kwargs)
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circuits = Circuit.objects.filter(
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models.Q(termination_a__in=pks) | models.Q(termination_z__in=pks)
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).exclude(pk__in=doomed_circuits)
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delete.alters_data = True
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for circuit in circuits:
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_set_circuit_terminations(circuit, {
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name: None
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for name in ('termination_a', 'termination_z')
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if getattr(circuit, f'{name}_id') in pks
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})
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def cache_related_objects(self):
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self._provider_network = self._region = self._site_group = self._site = self._location = None
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@ -507,8 +507,9 @@ class CircuitTerminationChangeLoggingTestCase(TestCase):
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self.assertIsNone(changes[0].postchange_data['termination_a'])
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@tag('regression') # Ref: #23134
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def test_deletion_leaves_another_terminations_pointer_alone(self):
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# A pointer referencing a different termination must never be cleared
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def test_deletion_resolves_the_pointer_from_the_database(self):
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# The pointer cleared is the one which references this termination, not the one named by
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# a stale in-memory term_side
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termination_a = self._tracked(lambda: CircuitTermination.objects.create(
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circuit=self.circuits[0], term_side='A', termination=self.sites[0],
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))
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@ -516,12 +517,52 @@ class CircuitTerminationChangeLoggingTestCase(TestCase):
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circuit=self.circuits[0], term_side='Z', termination=self.sites[1],
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))
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ObjectChange.objects.all().delete()
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termination_z_pk = termination_z.pk
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termination_z.term_side = 'A'
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self._tracked(termination_z.delete)
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self.circuits[0].refresh_from_db()
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self.assertEqual(self.circuits[0].termination_a_id, termination_a.pk)
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self.assertIsNone(self.circuits[0].termination_z_id)
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changes = self._circuit_changes(self.circuits[0])
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self.assertEqual(changes.count(), 1)
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self.assertEqual(changes[0].prechange_data['termination_z'], termination_z_pk)
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self.assertIsNone(changes[0].postchange_data['termination_z'])
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self.assertEqual(changes[0].postchange_data['termination_a'], termination_a.pk)
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@tag('regression') # Ref: #23134
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def test_cascade_deletion_records_circuit_update(self):
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# Deleting the terminating Site reaches the termination through the collector, which does
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# not call delete(). Both sides go in one record.
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termination_a = self._tracked(lambda: CircuitTermination.objects.create(
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circuit=self.circuits[0], term_side='A', termination=self.sites[0],
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))
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termination_z = self._tracked(lambda: CircuitTermination.objects.create(
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circuit=self.circuits[0], term_side='Z', termination=self.sites[0],
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))
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ObjectChange.objects.all().delete()
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termination_a_pk, termination_z_pk = termination_a.pk, termination_z.pk
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self._tracked(self.sites[0].delete)
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self.circuits[0].refresh_from_db()
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self.assertIsNone(self.circuits[0].termination_a_id)
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self.assertIsNone(self.circuits[0].termination_z_id)
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changes = self._circuit_changes(self.circuits[0])
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self.assertEqual(changes.count(), 1)
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self.assertEqual(changes[0].prechange_data['termination_a'], termination_a_pk)
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self.assertEqual(changes[0].prechange_data['termination_z'], termination_z_pk)
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self.assertIsNone(changes[0].postchange_data['termination_a'])
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self.assertIsNone(changes[0].postchange_data['termination_z'])
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# The clear must precede the DELETEs which the cascade emits for the terminations
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termination_delete = self._termination_change(
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termination_a_pk, ObjectChangeActionChoices.ACTION_DELETE
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)
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self.assertLess(changes[0].pk, termination_delete.pk)
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def test_circuit_deletion_records_no_pointer_update(self):
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self._tracked(lambda: CircuitTermination.objects.create(
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@ -1,7 +1,7 @@
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import logging
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from django.contrib.contenttypes.fields import GenericRelation
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from django.db import router
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from django.db import router, transaction
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from django.db.models.deletion import CASCADE, Collector
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from django.utils.translation import gettext as _
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@ -126,6 +126,18 @@ class CustomCollector(Collector):
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# Add the model that the generic relation points to as a dependency
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self.add_dependency(field.related_model, instance, reverse_dependency=True)
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def delete(self):
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# Clear any cached references to the objects being deleted first, so that each clear is
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# recorded and precedes the DELETE. Django nulls a SET_NULL column with a bulk UPDATE,
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# which emits no post_save and so is never change-logged. Models opt in by defining
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# clear_cached_references(); cascaded objects reach this the same as explicit deletions.
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with transaction.atomic(using=self.using):
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for model, instances in self.data.items():
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if clear_references := getattr(model, 'clear_cached_references', None):
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clear_references(instances, self)
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return super().delete()
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class DeleteMixin:
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"""
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