from django.core.exceptions import ImproperlyConfigured
from django.core.management.base import BaseCommand,CommandError
from django.core import serializers
from django.db import connections,router,DEFAULT_DB_ALIAS
from django.utils.datastructures import SortedDict
from optparse import make_option
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 load '
'fixtures into. Defaults to the "default" database.'),
make_option('-e', '--exclude', dest='exclude',action='append', default=[],
help='App to exclude (use multiple --exclude to exclude multiple apps).'),
make_option('-n', '--natural', action='store_true', dest='use_natural_keys', default=False,
help='Use natural keys if they are available.'),
)
help = 'Output the contents of the database as a fixture of the given format.'
args = '[appname appname.ModelName ...]'
def handle(self, *app_labels, **options):
from django.db.models import get_app,get_apps,get_models,get_model
format = options.get('format','json')
indent = options.get('indent',None)
using = options.get('database', DEFAULT_DB_ALIAS)
connection = connections[using]
exclude = options.get('exclude',[])
show_traceback = options.get('traceback', False)
use_natural_keys = options.get('use_natural_keys', False)
excluded_apps = set(get_app(app_label) for app_label in 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)
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)
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 not model._meta.proxy and router.allow_syncdb(using, model):
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)
def sort_dependencies(app_list):
"""Sort a list of app,modellist 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.
"""
from django.db.models import get_model,get_models
# Process the list of models, and get the list of dependencies
model_dependencies = []
models = set()
for app, model_list in app_list:
if model_list is None:
model_list = get_models(app)
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 = [get_model(*d.split('.')) for d 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'):
deps.append(rel_model)
for field in model._meta.many_to_many:
rel_model = field.rel.to
if hasattr(rel_model, 'natural_key'):
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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