def handle(self, *app_labels, **options):
from my_django.db.models import get_app, get_apps, get_model
format = options.get('format')
indent = options.get('indent')
using = options.get('database')
excludes = options.get('exclude')
show_traceback = options.get('traceback')
use_natural_keys = options.get('use_natural_keys')
use_base_manager = options.get('use_base_manager')
excluded_apps = set()
excluded_models = set()
for exclude in excludes:
if '.' in exclude:
app_label, model_name = exclude.split('.', 1)
model_obj = get_model(app_label, model_name)
if not model_obj:
raise CommandError('Unknown model in excludes: %s' %
exclude)
excluded_models.add(model_obj)
else:
try:
app_obj = get_app(exclude)
excluded_apps.add(app_obj)
except ImproperlyConfigured:
raise CommandError('Unknown app in excludes: %s' % exclude)
if len(app_labels) == 0:
app_list = SortedDict(
(app, None) for app in get_apps() if app not in excluded_apps)
else:
app_list = SortedDict()
for label in app_labels:
try:
app_label, model_label = label.split('.')
try:
app = get_app(app_label)
except ImproperlyConfigured:
raise CommandError("Unknown application: %s" %
app_label)
if app in excluded_apps:
continue
model = get_model(app_label, model_label)
if model is None:
raise CommandError("Unknown model: %s.%s" %
(app_label, model_label))
if app in app_list.keys():
if app_list[app] and model not in app_list[app]:
app_list[app].append(model)
else:
app_list[app] = [model]
except ValueError:
# This is just an app - no model qualifier
app_label = label
try:
app = get_app(app_label)
except ImproperlyConfigured:
raise CommandError("Unknown application: %s" %
app_label)
if app in excluded_apps:
continue
app_list[app] = None
# Check that the serialization format exists; this is a shortcut to
# avoid collating all the objects and _then_ failing.
if format not in serializers.get_public_serializer_formats():
raise CommandError("Unknown serialization format: %s" % format)
try:
serializers.get_serializer(format)
except KeyError:
raise CommandError("Unknown serialization format: %s" % format)
# Now collate the objects to be serialized.
objects = []
for model in sort_dependencies(app_list.items()):
if model in excluded_models:
continue
if not model._meta.proxy and router.allow_syncdb(using, model):
if use_base_manager:
objects.extend(model._base_manager.using(using).all())
else:
objects.extend(model._default_manager.using(using).all())
try:
return serializers.serialize(format,
objects,
indent=indent,
use_natural_keys=use_natural_keys)
except Exception, e:
if show_traceback:
raise
raise CommandError("Unable to serialize database: %s" % e)
class Collector(object):
def __init__(self, using):
self.using = using
# Initially, {model: set([instances])}, later values become lists.
self.data = {}
self.batches = {} # {model: {field: set([instances])}}
self.field_updates = {} # {model: {(field, value): set([instances])}}
# Tracks deletion-order dependency for databases without transactions
# or ability to defer constraint checks. Only concrete model classes
# should be included, as the dependencies exist only between actual
# database tables; proxy models are represented here by their concrete
# parent.
self.dependencies = {} # {model: set([models])}
def add(self, objs, source=None, nullable=False, reverse_dependency=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, set())
for obj in objs:
if obj not in instances:
new_objs.append(obj)
instances.update(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 source is not None and not nullable:
if reverse_dependency:
source, model = model, source
self.dependencies.setdefault(source._meta.concrete_model,
set()).add(model._meta.concrete_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,
reverse_dependency=False):
"""
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.
If 'reverse_dependency' is True, 'source' will be deleted before the
current model, rather than after. (Needed for cascading to parent
models, the one case in which the cascade follows the forwards
direction of an FK rather than the reverse direction.)
"""
new_objs = self.add(objs,
source,
nullable,
reverse_dependency=reverse_dependency)
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,
reverse_dependency=True)
if collect_related:
for related in model._meta.get_all_related_objects(
include_hidden=True, include_proxy_eq=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 = []
concrete_models = set()
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._meta.concrete_model)
if not (dependencies
and dependencies.difference(concrete_models)):
sorted_models.append(model)
concrete_models.add(model._meta.concrete_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 model, instances in self.data.items():
self.data[model] = sorted(instances, key=attrgetter("pk"))
# if possible, bring the models in an order suitable for databases that
# don't support transactions or cannot defer constraint 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)
