246 lines
9.8 KiB
Python
246 lines
9.8 KiB
Python
from operator import attrgetter
|
|
|
|
from django.db import connections, transaction, IntegrityError
|
|
from django.db.models import signals, sql
|
|
from django.db.models.sql.constants import GET_ITERATOR_CHUNK_SIZE
|
|
from django.utils.datastructures import SortedDict
|
|
from django.utils.functional import wraps
|
|
|
|
|
|
def CASCADE(collector, field, sub_objs, using):
|
|
collector.collect(sub_objs, source=field.rel.to,
|
|
source_attr=field.name, nullable=field.null)
|
|
if field.null and not connections[using].features.can_defer_constraint_checks:
|
|
collector.add_field_update(field, None, sub_objs)
|
|
|
|
def PROTECT(collector, field, sub_objs, using):
|
|
raise IntegrityError("Cannot delete some instances of model '%s' because "
|
|
"they are referenced through a protected foreign key: '%s.%s'" % (
|
|
field.rel.to.__name__, sub_objs[0].__class__.__name__, field.name
|
|
))
|
|
|
|
def SET(value):
|
|
if callable(value):
|
|
def set_on_delete(collector, field, sub_objs, using):
|
|
collector.add_field_update(field, value(), sub_objs)
|
|
else:
|
|
def set_on_delete(collector, field, sub_objs, using):
|
|
collector.add_field_update(field, value, sub_objs)
|
|
return set_on_delete
|
|
|
|
SET_NULL = SET(None)
|
|
|
|
def SET_DEFAULT(collector, field, sub_objs, using):
|
|
collector.add_field_update(field, field.get_default(), sub_objs)
|
|
|
|
def DO_NOTHING(collector, field, sub_objs, using):
|
|
pass
|
|
|
|
def force_managed(func):
|
|
@wraps(func)
|
|
def decorated(self, *args, **kwargs):
|
|
if not transaction.is_managed(using=self.using):
|
|
transaction.enter_transaction_management(using=self.using)
|
|
forced_managed = True
|
|
else:
|
|
forced_managed = False
|
|
try:
|
|
func(self, *args, **kwargs)
|
|
if forced_managed:
|
|
transaction.commit(using=self.using)
|
|
else:
|
|
transaction.commit_unless_managed(using=self.using)
|
|
finally:
|
|
if forced_managed:
|
|
transaction.leave_transaction_management(using=self.using)
|
|
return decorated
|
|
|
|
class Collector(object):
|
|
def __init__(self, using):
|
|
self.using = using
|
|
self.data = {} # {model: [instances]}
|
|
self.batches = {} # {model: {field: set([instances])}}
|
|
self.field_updates = {} # {model: {(field, value): set([instances])}}
|
|
self.dependencies = {} # {model: set([models])}
|
|
|
|
def add(self, objs, source=None, nullable=False):
|
|
"""
|
|
Adds 'objs' to the collection of objects to be deleted. If the call is
|
|
the result of a cascade, 'source' should be the model that caused it
|
|
and 'nullable' should be set to True, if the relation can be null.
|
|
|
|
Returns a list of all objects that were not already collected.
|
|
"""
|
|
if not objs:
|
|
return []
|
|
new_objs = []
|
|
model = objs[0].__class__
|
|
instances = self.data.setdefault(model, [])
|
|
for obj in objs:
|
|
if obj not in instances:
|
|
new_objs.append(obj)
|
|
instances.extend(new_objs)
|
|
# Nullable relationships can be ignored -- they are nulled out before
|
|
# deleting, and therefore do not affect the order in which objects have
|
|
# to be deleted.
|
|
if new_objs and source is not None and not nullable:
|
|
self.dependencies.setdefault(source, set()).add(model)
|
|
return new_objs
|
|
|
|
def add_batch(self, model, field, objs):
|
|
"""
|
|
Schedules a batch delete. Every instance of 'model' that is related to
|
|
an instance of 'obj' through 'field' will be deleted.
|
|
"""
|
|
self.batches.setdefault(model, {}).setdefault(field, set()).update(objs)
|
|
|
|
def add_field_update(self, field, value, objs):
|
|
"""
|
|
Schedules a field update. 'objs' must be a homogenous iterable
|
|
collection of model instances (e.g. a QuerySet).
|
|
"""
|
|
if not objs:
|
|
return
|
|
model = objs[0].__class__
|
|
self.field_updates.setdefault(
|
|
model, {}).setdefault(
|
|
(field, value), set()).update(objs)
|
|
|
|
def collect(self, objs, source=None, nullable=False, collect_related=True,
|
|
source_attr=None):
|
|
"""
|
|
Adds 'objs' to the collection of objects to be deleted as well as all
|
|
parent instances. 'objs' must be a homogenous iterable collection of
|
|
model instances (e.g. a QuerySet). If 'collect_related' is True,
|
|
related objects will be handled by their respective on_delete handler.
|
|
|
|
If the call is the result of a cascade, 'source' should be the model
|
|
that caused it and 'nullable' should be set to True, if the relation
|
|
can be null.
|
|
"""
|
|
|
|
new_objs = self.add(objs, source, nullable)
|
|
if not new_objs:
|
|
return
|
|
model = new_objs[0].__class__
|
|
|
|
# Recursively collect parent models, but not their related objects.
|
|
# These will be found by meta.get_all_related_objects()
|
|
for parent_model, ptr in model._meta.parents.iteritems():
|
|
if ptr:
|
|
parent_objs = [getattr(obj, ptr.name) for obj in new_objs]
|
|
self.collect(parent_objs, source=model,
|
|
source_attr=ptr.rel.related_name,
|
|
collect_related=False)
|
|
|
|
if collect_related:
|
|
for related in model._meta.get_all_related_objects(include_hidden=True):
|
|
field = related.field
|
|
if related.model._meta.auto_created:
|
|
self.add_batch(related.model, field, new_objs)
|
|
else:
|
|
sub_objs = self.related_objects(related, new_objs)
|
|
if not sub_objs:
|
|
continue
|
|
field.rel.on_delete(self, field, sub_objs, self.using)
|
|
|
|
# TODO This entire block is only needed as a special case to
|
|
# support cascade-deletes for GenericRelation. It should be
|
|
# removed/fixed when the ORM gains a proper abstraction for virtual
|
|
# or composite fields, and GFKs are reworked to fit into that.
|
|
for relation in model._meta.many_to_many:
|
|
if not relation.rel.through:
|
|
sub_objs = relation.bulk_related_objects(new_objs, self.using)
|
|
self.collect(sub_objs,
|
|
source=model,
|
|
source_attr=relation.rel.related_name,
|
|
nullable=True)
|
|
|
|
def related_objects(self, related, objs):
|
|
"""
|
|
Gets a QuerySet of objects related to ``objs`` via the relation ``related``.
|
|
|
|
"""
|
|
return related.model._base_manager.using(self.using).filter(
|
|
**{"%s__in" % related.field.name: objs}
|
|
)
|
|
|
|
def instances_with_model(self):
|
|
for model, instances in self.data.iteritems():
|
|
for obj in instances:
|
|
yield model, obj
|
|
|
|
def sort(self):
|
|
sorted_models = []
|
|
models = self.data.keys()
|
|
while len(sorted_models) < len(models):
|
|
found = False
|
|
for model in models:
|
|
if model in sorted_models:
|
|
continue
|
|
dependencies = self.dependencies.get(model)
|
|
if not (dependencies and dependencies.difference(sorted_models)):
|
|
sorted_models.append(model)
|
|
found = True
|
|
if not found:
|
|
return
|
|
self.data = SortedDict([(model, self.data[model])
|
|
for model in sorted_models])
|
|
|
|
@force_managed
|
|
def delete(self):
|
|
# sort instance collections
|
|
for instances in self.data.itervalues():
|
|
instances.sort(key=attrgetter("pk"))
|
|
|
|
# if possible, bring the models in an order suitable for databases that
|
|
# don't support transactions or cannot defer contraint checks until the
|
|
# end of a transaction.
|
|
self.sort()
|
|
|
|
# send pre_delete signals
|
|
for model, obj in self.instances_with_model():
|
|
if not model._meta.auto_created:
|
|
signals.pre_delete.send(
|
|
sender=model, instance=obj, using=self.using
|
|
)
|
|
|
|
# update fields
|
|
for model, instances_for_fieldvalues in self.field_updates.iteritems():
|
|
query = sql.UpdateQuery(model)
|
|
for (field, value), instances in instances_for_fieldvalues.iteritems():
|
|
query.update_batch([obj.pk for obj in instances],
|
|
{field.name: value}, self.using)
|
|
|
|
# reverse instance collections
|
|
for instances in self.data.itervalues():
|
|
instances.reverse()
|
|
|
|
# delete batches
|
|
for model, batches in self.batches.iteritems():
|
|
query = sql.DeleteQuery(model)
|
|
for field, instances in batches.iteritems():
|
|
query.delete_batch([obj.pk for obj in instances], self.using, field)
|
|
|
|
# delete instances
|
|
for model, instances in self.data.iteritems():
|
|
query = sql.DeleteQuery(model)
|
|
pk_list = [obj.pk for obj in instances]
|
|
query.delete_batch(pk_list, self.using)
|
|
|
|
# send post_delete signals
|
|
for model, obj in self.instances_with_model():
|
|
if not model._meta.auto_created:
|
|
signals.post_delete.send(
|
|
sender=model, instance=obj, using=self.using
|
|
)
|
|
|
|
# update collected instances
|
|
for model, instances_for_fieldvalues in self.field_updates.iteritems():
|
|
for (field, value), instances in instances_for_fieldvalues.iteritems():
|
|
for obj in instances:
|
|
setattr(obj, field.attname, value)
|
|
for model, instances in self.data.iteritems():
|
|
for instance in instances:
|
|
setattr(instance, model._meta.pk.attname, None)
|