Files
netbox/netbox/netbox/models/deletion.py

93 lines
3.3 KiB
Python

import logging
from django.contrib.contenttypes.fields import GenericRelation
from django.db import router
from django.db.models.deletion import CASCADE, Collector
logger = logging.getLogger("netbox.models.deletion")
class CustomCollector(Collector):
"""
Override Django's stock Collector to handle GenericRelations and ensure proper ordering of cascading deletions.
"""
def collect(
self,
objs,
source=None,
nullable=False,
collect_related=True,
source_attr=None,
reverse_dependency=False,
keep_parents=False,
fail_on_restricted=True,
):
# By default, Django will force the deletion of dependent objects before the parent only if the ForeignKey field
# is not nullable. We want to ensure proper ordering regardless, so if the ForeignKey has `on_delete=CASCADE`
# applied, we set `nullable` to False when calling `collect()`.
if objs and source and source_attr:
model = objs[0].__class__
field = model._meta.get_field(source_attr)
if field.remote_field.on_delete == CASCADE:
nullable = False
super().collect(
objs,
source=source,
nullable=nullable,
collect_related=collect_related,
source_attr=source_attr,
reverse_dependency=reverse_dependency,
keep_parents=keep_parents,
fail_on_restricted=fail_on_restricted,
)
# Add GenericRelations to the dependency graph
processed_relations = set()
for _, instances in list(self.data.items()):
for instance in instances:
# Get all GenericRelations for this model
for field in instance._meta.private_fields:
if isinstance(field, GenericRelation):
# Create a unique key for this relation
relation_key = f"{instance._meta.model_name}.{field.name}"
if relation_key in processed_relations:
continue
processed_relations.add(relation_key)
# Add the model that the generic relation points to as a dependency
self.add_dependency(field.related_model, instance, reverse_dependency=True)
class DeleteMixin:
"""
Mixin to override the model delete function to use our custom collector.
"""
def delete(self, using=None, keep_parents=False):
"""
Override delete to use our custom collector.
"""
using = using or router.db_for_write(self.__class__, instance=self)
assert self._get_pk_val() is not None, "%s object can't be deleted because its %s attribute is set to None." % (
self._meta.object_name,
self._meta.pk.attname,
)
collector = CustomCollector(using=using)
collector.collect([self], keep_parents=keep_parents)
return collector.delete()
delete.alters_data = True
@classmethod
def verify_mro(cls, instance):
"""
Verify that this mixin is first in the MRO.
"""
mro = instance.__class__.__mro__
if mro.index(cls) != 0:
raise RuntimeError(f"{cls.__name__} must be first in the MRO. Current MRO: {mro}")