/usr/lib/python3/dist-packages/reversion/revisions.py is in python3-django-reversion 1.10.0-1.
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from __future__ import unicode_literals
import operator, warnings
from functools import wraps, reduce, partial
from threading import local
from weakref import WeakValueDictionary
import copy
from collections import defaultdict
try:
from django.apps import apps
get_model = apps.get_model
except ImportError: # For Django < 1.7 pragma: no cover
from django.db.models import get_model
from django.contrib.contenttypes.models import ContentType
from django.core import serializers
from django.core.exceptions import ObjectDoesNotExist
from django.core.signals import request_finished
from django.db import models, connection, transaction
from django.db.models import Q, Max
from django.db.models.query import QuerySet
from django.db.models.signals import post_save
from django.utils.encoding import force_text
from reversion.models import Revision, Version, has_int_pk
from reversion.signals import pre_revision_commit, post_revision_commit
from reversion.errors import RevisionManagementError, RegistrationError
class VersionAdapter(object):
"""Adapter class for serializing a registered model."""
# Fields to include in the serialized data.
fields = ()
# Fields to exclude from the serialized data.
exclude = ()
# Foreign key relationships to follow when saving a version of this model.
follow = ()
# The serialization format to use.
format = "json"
def __init__(self, model):
"""Initializes the version adapter."""
self.model = model
def get_fields_to_serialize(self):
"""Returns an iterable of field names to serialize in the version data."""
opts = self.model._meta.concrete_model._meta
fields = self.fields or (field.name for field in opts.local_fields + opts.local_many_to_many)
fields = (opts.get_field(field) for field in fields if not field in self.exclude)
for field in fields:
if field.rel:
yield field.name
else:
yield field.attname
def get_followed_relations(self, obj):
"""Returns an iterable of related models that should be included in the revision data."""
for relationship in self.follow:
# Clear foreign key cache.
try:
related_field = obj._meta.get_field(relationship)
except models.FieldDoesNotExist:
pass
else:
if isinstance(related_field, models.ForeignKey):
if hasattr(obj, related_field.get_cache_name()):
delattr(obj, related_field.get_cache_name())
# Get the referenced obj(s).
try:
related = getattr(obj, relationship)
except ObjectDoesNotExist: # pragma: no cover
continue
if isinstance(related, models.Model):
yield related
elif isinstance(related, (models.Manager, QuerySet)):
for related_obj in related.all():
yield related_obj
elif related is not None: # pragma: no cover
raise TypeError("Cannot follow the relationship {relationship}. Expected a model or QuerySet, found {related}".format(
relationship = relationship,
related = related,
))
def get_serialization_format(self):
"""Returns the serialization format to use."""
return self.format
def get_serialized_data(self, obj):
"""Returns a string of serialized data for the given obj."""
return serializers.serialize(
self.get_serialization_format(),
(obj,),
fields = list(self.get_fields_to_serialize()),
)
def get_version_data(self, obj, db=None):
"""Creates the version data to be saved to the version model."""
object_id = force_text(obj.pk)
content_type = ContentType.objects.db_manager(db).get_for_model(obj)
if has_int_pk(obj.__class__):
object_id_int = int(obj.pk)
else:
object_id_int = None
return {
"object_id": object_id,
"object_id_int": object_id_int,
"content_type": content_type,
"format": self.get_serialization_format(),
"serialized_data": self.get_serialized_data(obj),
"object_repr": force_text(obj),
}
class RevisionContextStackFrame(object):
def __init__(self, is_managing_manually, is_invalid=False, ignore_duplicates=False):
self.is_managing_manually = is_managing_manually
self.is_invalid = is_invalid
self.ignore_duplicates = ignore_duplicates
self.objects = defaultdict(dict)
self.meta = []
def fork(self, is_managing_manually):
return RevisionContextStackFrame(is_managing_manually, self.is_invalid, self.ignore_duplicates)
def join(self, other_context):
if not other_context.is_invalid:
for manager_name, object_versions in other_context.objects.items():
self.objects[manager_name].update(object_versions)
self.meta.extend(other_context.meta)
class RevisionContextManager(local):
"""Manages the state of the current revision."""
def __init__(self):
"""Initializes the revision state."""
self.clear()
# Connect to the request finished signal.
request_finished.connect(self._request_finished_receiver)
def clear(self):
"""Puts the revision manager back into its default state."""
self._user = None
self._comment = ""
self._stack = []
self._db = None
def is_active(self):
"""Returns whether there is an active revision for this thread."""
return bool(self._stack)
def _assert_active(self):
"""Checks for an active revision, throwning an exception if none."""
if not self.is_active(): # pragma: no cover
raise RevisionManagementError("There is no active revision for this thread")
@property
def _current_frame(self):
self._assert_active()
return self._stack[-1]
def start(self, manage_manually=False):
"""
Begins a revision for this thread.
This MUST be balanced by a call to `end`. It is recommended that you
leave these methods alone and instead use the revision context manager
or the `create_revision` decorator.
"""
if self.is_active():
self._stack.append(self._current_frame.fork(manage_manually))
else:
self._stack.append(RevisionContextStackFrame(manage_manually))
def end(self):
"""Ends a revision for this thread."""
self._assert_active()
stack_frame = self._stack.pop()
if self._stack:
self._current_frame.join(stack_frame)
else:
try:
if not stack_frame.is_invalid:
# Save the revision data.
for manager, manager_context in stack_frame.objects.items():
manager.save_revision(
dict(
(obj, callable(data) and data() or data)
for obj, data
in manager_context.items()
if obj.pk is not None
),
user = self._user,
comment = self._comment,
meta = stack_frame.meta,
ignore_duplicates = stack_frame.ignore_duplicates,
db = self._db,
)
finally:
self.clear()
# Revision context properties that apply to the entire stack.
def get_db(self):
"""Returns the current DB alias being used."""
return self._db
def set_db(self, db):
"""Sets the DB alias to use."""
self._db = db
def set_user(self, user):
"""Sets the current user for the revision."""
self._assert_active()
self._user = user
def get_user(self):
"""Gets the current user for the revision."""
self._assert_active()
return self._user
def set_comment(self, comment):
"""Sets the comments for the revision."""
self._assert_active()
self._comment = comment
def get_comment(self):
"""Gets the current comment for the revision."""
self._assert_active()
return self._comment
# Revision context properties that apply to the current stack frame.
def is_managing_manually(self):
"""Returns whether this revision context has manual management enabled."""
return self._current_frame.is_managing_manually
def invalidate(self):
"""Marks this revision as broken, so should not be commited."""
self._current_frame.is_invalid = True
def is_invalid(self):
"""Checks whether this revision is invalid."""
return self._current_frame.is_invalid
def add_to_context(self, manager, obj, version_data):
"""Adds an object to the current revision."""
self._current_frame.objects[manager][obj] = version_data
def add_meta(self, cls, **kwargs):
"""Adds a class of meta information to the current revision."""
self._current_frame.meta.append((cls, kwargs))
def set_ignore_duplicates(self, ignore_duplicates):
"""Sets whether to ignore duplicate revisions."""
self._current_frame.ignore_duplicates = ignore_duplicates
def get_ignore_duplicates(self):
"""Gets whether to ignore duplicate revisions."""
return self._current_frame.ignore_duplicates
# Signal receivers.
def _request_finished_receiver(self, **kwargs):
"""
Called at the end of a request, ensuring that any open revisions
are closed. Not closing all active revisions can cause memory leaks
and weird behaviour.
"""
while self.is_active(): # pragma: no cover
self.end()
# High-level context management.
def create_revision(self, manage_manually=False):
"""
Marks up a block of code as requiring a revision to be created.
The returned context manager can also be used as a decorator.
"""
return RevisionContext(self, manage_manually)
class RevisionContext(object):
"""An individual context for a revision."""
def __init__(self, context_manager, manage_manually):
"""Initializes the revision context."""
self._context_manager = context_manager
self._manage_manually = manage_manually
def __enter__(self):
"""Enters a block of revision management."""
self._context_manager.start(self._manage_manually)
def __exit__(self, exc_type, exc_value, traceback):
"""Leaves a block of revision management."""
try:
if exc_type is not None:
self._context_manager.invalidate()
finally:
self._context_manager.end()
def __call__(self, func):
"""Allows this revision context to be used as a decorator."""
@wraps(func)
def do_revision_context(*args, **kwargs):
with self:
return func(*args, **kwargs)
return do_revision_context
# A shared, thread-safe context manager.
revision_context_manager = RevisionContextManager()
class RevisionManager(object):
"""Manages the configuration and creation of revisions."""
_created_managers = WeakValueDictionary()
@classmethod
def get_created_managers(cls):
"""Returns all created revision managers."""
return list(cls._created_managers.items())
@classmethod
def get_manager(cls, manager_slug):
"""Returns the manager with the given slug."""
if manager_slug in cls._created_managers:
return cls._created_managers[manager_slug]
raise RegistrationError("No revision manager exists with the slug %r" % manager_slug) # pragma: no cover
def __init__(self, manager_slug, revision_context_manager=revision_context_manager):
"""Initializes the revision manager."""
# Check the slug is unique for this revision manager.
if manager_slug in RevisionManager._created_managers: # pragma: no cover
raise RegistrationError("A revision manager has already been created with the slug %r" % manager_slug)
# Store a reference to this manager.
self.__class__._created_managers[manager_slug] = self
# Store config params.
self._manager_slug = manager_slug
self._registered_models = {}
self._revision_context_manager = revision_context_manager
self._eager_signals = {}
self._signals = {}
# Proxies to common context methods.
self._revision_context = revision_context_manager.create_revision()
# Registration methods.
def _registration_key_for_model(self, model):
meta = model._meta
return (
meta.app_label,
meta.model_name,
)
def is_registered(self, model):
"""
Checks whether the given model has been registered with this revision
manager.
"""
return self._registration_key_for_model(model) in self._registered_models
def get_registered_models(self):
"""Returns an iterable of all registered models."""
return [
get_model(*key)
for key
in self._registered_models.keys()
]
def register(self, model=None, adapter_cls=VersionAdapter, signals=None, eager_signals=None, **field_overrides):
"""Registers a model with this revision manager."""
# Default to post_save if no signals are given
if signals is None and eager_signals is None:
signals = [post_save]
# Store signals for usage in the signal receiver
self._eager_signals[model] = list(eager_signals or [])
self._signals[model] = list(signals or [])
# Return a class decorator if model is not given
if model is None:
return partial(self.register, adapter_cls=adapter_cls, **field_overrides)
# Prevent multiple registration.
if self.is_registered(model):
raise RegistrationError("{model} has already been registered with django-reversion".format(
model = model,
))
# Perform any customization.
if field_overrides:
adapter_cls = type(adapter_cls.__name__, (adapter_cls,), field_overrides)
# Perform the registration.
adapter_obj = adapter_cls(model)
self._registered_models[self._registration_key_for_model(model)] = adapter_obj
# Connect to the selected signals of the model.
all_signals = self._signals[model] + self._eager_signals[model]
for signal in all_signals:
signal.connect(self._signal_receiver, model)
return model
def get_adapter(self, model):
"""Returns the registration information for the given model class."""
if self.is_registered(model):
return self._registered_models[self._registration_key_for_model(model)]
raise RegistrationError("{model} has not been registered with django-reversion".format(
model = model,
))
def unregister(self, model):
"""Removes a model from version control."""
if not self.is_registered(model):
raise RegistrationError("{model} has not been registered with django-reversion".format(
model = model,
))
del self._registered_models[self._registration_key_for_model(model)]
all_signals = self._signals[model] + self._eager_signals[model]
for signal in all_signals:
signal.disconnect(self._signal_receiver, model)
del self._signals[model]
del self._eager_signals[model]
def _follow_relationships(self, objects):
"""Follows all relationships in the given set of objects."""
followed = set()
def _follow(obj, exclude_concrete):
# Check the pk first because objects without a pk are not hashable
if obj.pk is None or obj in followed or (obj.__class__, obj.pk) == exclude_concrete:
return
followed.add(obj)
adapter = self.get_adapter(obj.__class__)
for related in adapter.get_followed_relations(obj):
_follow(related, exclude_concrete)
for obj in objects:
exclude_concrete = None
if obj._meta.proxy:
exclude_concrete = (obj._meta.concrete_model, obj.pk)
_follow(obj, exclude_concrete)
return followed
def _get_versions(self, db=None):
"""Returns all versions that apply to this manager."""
return Version.objects.using(db).filter(
revision__manager_slug = self._manager_slug,
).select_related("revision")
def save_revision(self, objects, ignore_duplicates=False, user=None, comment="", meta=(), db=None):
"""Saves a new revision."""
# Adapt the objects to a dict.
if isinstance(objects, (list, tuple)):
objects = dict(
(obj, self.get_adapter(obj.__class__).get_version_data(obj, db))
for obj in objects
)
# Create the revision.
if objects:
# Follow relationships.
for obj in self._follow_relationships(objects.keys()):
if not obj in objects:
adapter = self.get_adapter(obj.__class__)
objects[obj] = adapter.get_version_data(obj)
# Create all the versions without saving them
ordered_objects = list(objects.keys())
new_versions = [Version(**objects[obj]) for obj in ordered_objects]
# Check if there's some change in all the revision's objects.
save_revision = True
if ignore_duplicates:
# Find the latest revision amongst the latest previous version of each object.
subqueries = [Q(object_id=version.object_id, content_type=version.content_type) for version in new_versions]
subqueries = reduce(operator.or_, subqueries)
latest_revision = self._get_versions(db).filter(subqueries).aggregate(Max("revision"))["revision__max"]
# If we have a latest revision, compare it to the current revision.
if latest_revision is not None:
previous_versions = self._get_versions(db).filter(revision=latest_revision).values_list("serialized_data", flat=True)
if len(previous_versions) == len(new_versions):
all_serialized_data = [version.serialized_data for version in new_versions]
if sorted(previous_versions) == sorted(all_serialized_data):
save_revision = False
# Only save if we're always saving, or have changes.
if save_revision:
# Save a new revision.
revision = Revision(
manager_slug = self._manager_slug,
user = user,
comment = comment,
)
# Send the pre_revision_commit signal.
pre_revision_commit.send(self,
instances = ordered_objects,
revision = revision,
versions = new_versions,
)
# Save the revision.
with transaction.atomic(using=db):
revision.save(using=db)
# Save version models.
for version in new_versions:
version.revision = revision
version.save()
# Save the meta information.
for cls, kwargs in meta:
cls._default_manager.db_manager(db).create(revision=revision, **kwargs)
# Send the post_revision_commit signal.
post_revision_commit.send(self,
instances = ordered_objects,
revision = revision,
versions = new_versions,
)
# Return the revision.
return revision
# Revision management API.
def get_for_object_reference(self, model, object_id, db=None):
"""
Returns all versions for the given object reference.
The results are returned with the most recent versions first.
"""
content_type = ContentType.objects.db_manager(db).get_for_model(model)
versions = self._get_versions(db).filter(
content_type = content_type,
).select_related("revision")
if has_int_pk(model):
# We can do this as a fast, indexed lookup.
object_id_int = int(object_id)
versions = versions.filter(object_id_int=object_id_int)
else:
# We can't do this using an index. Never mind.
object_id = force_text(object_id)
versions = versions.filter(object_id=object_id)
versions = versions.order_by("-pk")
return versions
def get_for_object(self, obj, db=None):
"""
Returns all the versions of the given object, ordered by date created.
The results are returned with the most recent versions first.
"""
return self.get_for_object_reference(obj.__class__, obj.pk, db)
def get_unique_for_object(self, obj, db=None):
"""
Returns unique versions associated with the object.
The results are returned with the most recent versions first.
"""
warnings.warn(
"Use get_for_object().get_unique() instead of get_unique_for_object().",
PendingDeprecationWarning)
return list(self.get_for_object(obj, db).get_unique())
def get_for_date(self, object, date, db=None):
"""Returns the latest version of an object for the given date."""
versions = self.get_for_object(object, db)
versions = versions.filter(revision__date_created__lte=date)
try:
version = versions[0]
except IndexError:
raise Version.DoesNotExist
else:
return version
def get_deleted(self, model_class, db=None, model_db=None):
"""
Returns all the deleted versions for the given model class.
The results are returned with the most recent versions first.
"""
model_db = model_db or db
content_type = ContentType.objects.db_manager(db).get_for_model(model_class)
live_pk_queryset = model_class._default_manager.db_manager(model_db).all().values_list("pk", flat=True)
versioned_objs = self._get_versions(db).filter(
content_type = content_type,
)
if has_int_pk(model_class):
# If the model and version data are in different databases, decouple the queries.
if model_db != db:
live_pk_queryset = list(live_pk_queryset.iterator())
# We can do this as a fast, in-database join.
deleted_version_pks = versioned_objs.exclude(
object_id_int__in = live_pk_queryset
).values_list("object_id_int")
else:
# This join has to be done as two separate queries.
deleted_version_pks = versioned_objs.exclude(
object_id__in = list(live_pk_queryset.iterator())
).values_list("object_id")
deleted_version_pks = deleted_version_pks.annotate(
latest_pk = Max("pk")
).values_list("latest_pk", flat=True)
# HACK: MySQL deals extremely badly with this as a subquery, and can hang infinitely.
# TODO: If a version is identified where this bug no longer applies, we can add a version specifier.
if connection.vendor == "mysql": # pragma: no cover
deleted_version_pks = list(deleted_version_pks)
# Return the deleted versions!
return self._get_versions(db).filter(pk__in=deleted_version_pks).order_by("-pk")
# Signal receivers.
def _signal_receiver(self, instance, signal, **kwargs):
"""Adds registered models to the current revision, if any."""
if self._revision_context_manager.is_active() and not self._revision_context_manager.is_managing_manually():
eager = signal in self._eager_signals[instance.__class__]
adapter = self.get_adapter(instance.__class__)
if eager:
# pre_delete is a special case, because the instance will
# be modified by django right after this.
# don't use a lambda, but get the data out now.
version_data = adapter.get_version_data(instance, self._revision_context_manager._db)
self._revision_context_manager.add_to_context(self, copy.copy(instance), version_data)
for obj in self._follow_relationships([instance]):
adapter = self.get_adapter(obj.__class__)
version_data = adapter.get_version_data(obj, self._revision_context_manager._db)
self._revision_context_manager.add_to_context(self, copy.copy(obj), version_data)
else:
version_data = lambda: adapter.get_version_data(instance, self._revision_context_manager._db)
self._revision_context_manager.add_to_context(self, instance, version_data)
# A shared revision manager.
default_revision_manager = RevisionManager("default")
# Easy registration methods.
register = default_revision_manager.register
is_registered = default_revision_manager.is_registered
unregister = default_revision_manager.unregister
get_adapter = default_revision_manager.get_adapter
get_registered_models = default_revision_manager.get_registered_models
# Context management.
create_revision = revision_context_manager.create_revision
# Revision meta data.
get_db = revision_context_manager.get_db
set_db = revision_context_manager.set_db
get_user = revision_context_manager.get_user
set_user = revision_context_manager.set_user
get_comment = revision_context_manager.get_comment
set_comment = revision_context_manager.set_comment
add_meta = revision_context_manager.add_meta
get_ignore_duplicates = revision_context_manager.get_ignore_duplicates
set_ignore_duplicates = revision_context_manager.set_ignore_duplicates
# Low level API.
get_for_object_reference = default_revision_manager.get_for_object_reference
get_for_object = default_revision_manager.get_for_object
get_unique_for_object = default_revision_manager.get_unique_for_object
get_for_date = default_revision_manager.get_for_date
get_deleted = default_revision_manager.get_deleted
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