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import warnings
from collections import OrderedDict
from optparse import make_option
from django.apps import apps
from django.core.management.base import BaseCommand, CommandError
from django.core import serializers
from django.db import router, DEFAULT_DB_ALIAS
from django.utils.deprecation import RemovedInDjango19Warning
class Command(BaseCommand):
option_list = BaseCommand.option_list + (
make_option('--format', default='json', dest='format',
help='Specifies the output serialization format for fixtures.'),
make_option('--indent', default=None, dest='indent', type='int',
help='Specifies the indent level to use when pretty-printing output'),
make_option('--database', action='store', dest='database',
default=DEFAULT_DB_ALIAS,
help='Nominates a specific database to dump fixtures from. '
'Defaults to the "default" database.'),
make_option('-e', '--exclude', dest='exclude', action='append', default=[],
help='An app_label or app_label.ModelName to exclude '
'(use multiple --exclude to exclude multiple apps/models).'),
make_option('-n', '--natural', action='store_true', dest='use_natural_keys', default=False,
help='Use natural keys if they are available (deprecated: use --natural-foreign instead).'),
make_option('--natural-foreign', action='store_true', dest='use_natural_foreign_keys', default=False,
help='Use natural foreign keys if they are available.'),
make_option('--natural-primary', action='store_true', dest='use_natural_primary_keys', default=False,
help='Use natural primary keys if they are available.'),
make_option('-a', '--all', action='store_true', dest='use_base_manager', default=False,
help="Use Django's base manager to dump all models stored in the database, "
"including those that would otherwise be filtered or modified by a custom manager."),
make_option('--pks', dest='primary_keys',
help="Only dump objects with given primary keys. "
"Accepts a comma separated list of keys. "
"This option will only work when you specify one model."),
)
help = ("Output the contents of the database as a fixture of the given "
"format (using each model's default manager unless --all is "
"specified).")
args = '[app_label app_label.ModelName ...]'
def handle(self, *app_labels, **options):
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')
if use_natural_keys:
warnings.warn("``--natural`` is deprecated; use ``--natural-foreign`` instead.",
RemovedInDjango19Warning)
use_natural_foreign_keys = options.get('use_natural_foreign_keys') or use_natural_keys
use_natural_primary_keys = options.get('use_natural_primary_keys')
use_base_manager = options.get('use_base_manager')
pks = options.get('primary_keys')
if pks:
primary_keys = pks.split(',')
else:
primary_keys = []
excluded_apps = set()
excluded_models = set()
for exclude in excludes:
if '.' in exclude:
try:
model = apps.get_model(exclude)
except LookupError:
raise CommandError('Unknown model in excludes: %s' % exclude)
excluded_models.add(model)
else:
try:
app_config = apps.get_app_config(exclude)
except LookupError:
raise CommandError('Unknown app in excludes: %s' % exclude)
excluded_apps.add(app_config)
if len(app_labels) == 0:
if primary_keys:
raise CommandError("You can only use --pks option with one model")
app_list = OrderedDict((app_config, None)
for app_config in apps.get_app_configs()
if app_config.models_module is not None and app_config not in excluded_apps)
else:
if len(app_labels) > 1 and primary_keys:
raise CommandError("You can only use --pks option with one model")
app_list = OrderedDict()
for label in app_labels:
try:
app_label, model_label = label.split('.')
try:
app_config = apps.get_app_config(app_label)
except LookupError:
raise CommandError("Unknown application: %s" % app_label)
if app_config.models_module is None or app_config in excluded_apps:
continue
try:
model = app_config.get_model(model_label)
except LookupError:
raise CommandError("Unknown model: %s.%s" % (app_label, model_label))
app_list_value = app_list.setdefault(app_config, [])
# We may have previously seen a "all-models" request for
# this app (no model qualifier was given). In this case
# there is no need adding specific models to the list.
if app_list_value is not None:
if model not in app_list_value:
app_list_value.append(model)
except ValueError:
if primary_keys:
raise CommandError("You can only use --pks option with one model")
# This is just an app - no model qualifier
app_label = label
try:
app_config = apps.get_app_config(app_label)
except LookupError:
raise CommandError("Unknown application: %s" % app_label)
if app_config.models_module is None or app_config in excluded_apps:
continue
app_list[app_config] = 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():
try:
serializers.get_serializer(format)
except serializers.SerializerDoesNotExist:
pass
raise CommandError("Unknown serialization format: %s" % format)
def get_objects():
# Collate the objects to be serialized.
for model in sort_dependencies(app_list.items()):
if model in excluded_models:
continue
if not model._meta.proxy and router.allow_migrate(using, model):
if use_base_manager:
objects = model._base_manager
else:
objects = model._default_manager
queryset = objects.using(using).order_by(model._meta.pk.name)
if primary_keys:
queryset = queryset.filter(pk__in=primary_keys)
for obj in queryset.iterator():
yield obj
try:
self.stdout.ending = None
serializers.serialize(format, get_objects(), indent=indent,
use_natural_foreign_keys=use_natural_foreign_keys,
use_natural_primary_keys=use_natural_primary_keys,
stream=self.stdout)
except Exception as e:
if show_traceback:
raise
raise CommandError("Unable to serialize database: %s" % e)
def sort_dependencies(app_list):
"""Sort a list of (app_config, models) pairs into a single list of models.
The single list of models is sorted so that any model with a natural key
is serialized before a normal model, and any model with a natural key
dependency has it's dependencies serialized first.
"""
# Process the list of models, and get the list of dependencies
model_dependencies = []
models = set()
for app_config, model_list in app_list:
if model_list is None:
model_list = app_config.get_models()
for model in model_list:
models.add(model)
# Add any explicitly defined dependencies
if hasattr(model, 'natural_key'):
deps = getattr(model.natural_key, 'dependencies', [])
if deps:
deps = [apps.get_model(dep) for dep in deps]
else:
deps = []
# Now add a dependency for any FK or M2M relation with
# a model that defines a natural key
for field in model._meta.fields:
if hasattr(field.rel, 'to'):
rel_model = field.rel.to
if hasattr(rel_model, 'natural_key') and rel_model != model:
deps.append(rel_model)
for field in model._meta.many_to_many:
rel_model = field.rel.to
if hasattr(rel_model, 'natural_key') and rel_model != model:
deps.append(rel_model)
model_dependencies.append((model, deps))
model_dependencies.reverse()
# Now sort the models to ensure that dependencies are met. This
# is done by repeatedly iterating over the input list of models.
# If all the dependencies of a given model are in the final list,
# that model is promoted to the end of the final list. This process
# continues until the input list is empty, or we do a full iteration
# over the input models without promoting a model to the final list.
# If we do a full iteration without a promotion, that means there are
# circular dependencies in the list.
model_list = []
while model_dependencies:
skipped = []
changed = False
while model_dependencies:
model, deps = model_dependencies.pop()
# If all of the models in the dependency list are either already
# on the final model list, or not on the original serialization list,
# then we've found another model with all it's dependencies satisfied.
found = True
for candidate in ((d not in models or d in model_list) for d in deps):
if not candidate:
found = False
if found:
model_list.append(model)
changed = True
else:
skipped.append((model, deps))
if not changed:
raise CommandError("Can't resolve dependencies for %s in serialized app list." %
', '.join('%s.%s' % (model._meta.app_label, model._meta.object_name)
for model, deps in sorted(skipped, key=lambda obj: obj[0].__name__))
)
model_dependencies = skipped
return model_list
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