def add(self, obj):
"""Add a new object 'obj' to the database and assign it an oid."""
if self.opened is None:
raise ConnectionStateError("The database connection is closed")
marker = object()
oid = getattr(obj, "_p_oid", marker)
if oid is marker:
raise TypeError(
"Only first-class persistent objects may be"
" added to a Connection.", obj)
elif obj._p_jar is None:
self._add(obj, self.new_oid())
elif obj._p_jar is not self:
raise InvalidObjectReference(obj, obj._p_jar)
def _commit(self, transaction):
"""Commit changes to an object"""
if self._import:
# We are importing an export file. We alsways do this
# while making a savepoint so we can copy export data
# directly to our storage, typically a TmpStore.
self._importDuringCommit(transaction, *self._import)
self._import = None
# Just in case an object is added as a side-effect of storing
# a modified object. If, for example, a __getstate__() method
# calls add(), the newly added objects will show up in
# _added_during_commit. This sounds insane, but has actually
# happened.
self._added_during_commit = []
if self._invalidatedCache:
raise ConflictError()
for obj in self._registered_objects:
oid = obj._p_oid
assert oid
if oid in self._conflicts:
raise ReadConflictError(object=obj)
if obj._p_jar is not self:
raise InvalidObjectReference(obj, obj._p_jar)
elif oid in self._added:
assert obj._p_serial == z64
elif obj._p_changed:
if oid in self._invalidated:
resolve = getattr(obj, "_p_resolveConflict", None)
if resolve is None:
raise ConflictError(object=obj)
self._modified.append(oid)
else:
# Nothing to do. It's been said that it's legal, e.g., for
# an object to set _p_changed to false after it's been
# changed and registered.
continue
self._store_objects(ObjectWriter(obj), transaction)
for obj in self._added_during_commit:
self._store_objects(ObjectWriter(obj), transaction)
self._added_during_commit = None
def add(self, obj):
"""Add a new object 'obj' to the database and assign it an oid."""
if self._opened is None:
raise ConnectionStateError("The database connection is closed")
marker = object()
oid = getattr(obj, "_p_oid", marker)
if oid is marker:
raise TypeError(
"Only first-class persistent objects may be"
" added to a Connection.", obj)
elif obj._p_jar is None:
assert obj._p_oid is None
oid = obj._p_oid = self._storage.new_oid()
obj._p_jar = self
if self._added_during_commit is not None:
self._added_during_commit.append(obj)
self._register(obj)
# Add to _added after calling register(), so that _added
# can be used as a test for whether the object has been
# registered with the transaction.
self._added[oid] = obj
elif obj._p_jar is not self:
raise InvalidObjectReference(obj, obj._p_jar)
def persistent_id(self, obj):
"""Return the persistent id for obj.
>>> from ZODB.tests.util import P
>>> class DummyJar:
... xrefs = True
... def new_oid(self):
... return 42
... def db(self):
... return self
... databases = {}
>>> jar = DummyJar()
>>> class O:
... _p_jar = jar
>>> writer = ObjectWriter(O)
Normally, object references include the oid and a cached named
reference to the class. Having the class information
available allows fast creation of the ghost, avoiding
requiring an additional database lookup.
>>> bob = P('bob')
>>> oid, cls = writer.persistent_id(bob)
>>> oid
42
>>> cls is P
True
If a persistent object does not already have an oid and jar,
these will be assigned by persistent_id():
>>> bob._p_oid
42
>>> bob._p_jar is jar
True
If the object already has a persistent id, the id is not changed:
>>> bob._p_oid = 24
>>> oid, cls = writer.persistent_id(bob)
>>> oid
24
>>> cls is P
True
If the jar doesn't match that of the writer, an error is raised:
>>> bob._p_jar = DummyJar()
>>> writer.persistent_id(bob)
... # doctest: +NORMALIZE_WHITESPACE +ELLIPSIS
Traceback (most recent call last):
...
InvalidObjectReference:
('Attempt to store an object from a foreign database connection',
<ZODB.serialize.DummyJar instance at ...>, P(bob))
Constructor arguments used by __new__(), as returned by
__getnewargs__(), can affect memory allocation, but may also
change over the life of the object. This makes it useless to
cache even the object's class.
>>> class PNewArgs(P):
... def __getnewargs__(self):
... return ()
>>> sam = PNewArgs('sam')
>>> writer.persistent_id(sam)
42
>>> sam._p_oid
42
>>> sam._p_jar is jar
True
Check that simple objects don't get accused of persistence:
>>> writer.persistent_id(42)
>>> writer.persistent_id(object())
Check that a classic class doesn't get identified improperly:
>>> class ClassicClara:
... pass
>>> clara = ClassicClara()
>>> writer.persistent_id(clara)
"""
# Most objects are not persistent. The following cheap test
# identifies most of them. For these, we return None,
# signalling that the object should be pickled normally.
if not isinstance(obj, (Persistent, type, WeakRef)):
# Not persistent, pickle normally
return None
# Any persistent object must have an oid:
try:
oid = obj._p_oid
except AttributeError:
# Not persistent, pickle normally
return None
if not (oid is None or isinstance(oid, str)):
# Deserves a closer look:
# Make sure it's not a descriptor
if hasattr(oid, '__get__'):
# The oid is a descriptor. That means obj is a non-persistent
# class whose instances are persistent, so ...
# Not persistent, pickle normally
return None
if oid is WeakRefMarker:
# we have a weakref, see weakref.py
oid = obj.oid
if oid is None:
target = obj() # get the referenced object
oid = target._p_oid
if oid is None:
# Here we are causing the object to be saved in
# the database. One could argue that we shouldn't
# do this, because a weakref should not cause an object
# to be added. We'll be optimistic, though, and
# assume that the object will be added eventually.
oid = self._jar.new_oid()
target._p_jar = self._jar
target._p_oid = oid
self._stack.append(target)
obj.oid = oid
obj.dm = target._p_jar
obj.database_name = obj.dm.db().database_name
if obj.dm is self._jar:
return ['w', (oid, )]
else:
return ['w', (oid, obj.database_name)]
# Since we have an oid, we have either a persistent instance
# (an instance of Persistent), or a persistent class.
# NOTE! Persistent classes don't (and can't) subclass persistent.
database_name = None
if oid is None:
oid = obj._p_oid = self._jar.new_oid()
obj._p_jar = self._jar
self._stack.append(obj)
elif obj._p_jar is not self._jar:
if not self._jar.db().xrefs:
raise InvalidObjectReference(
"Database %r doesn't allow implicit cross-database "
"references" % self._jar.db().database_name, self._jar,
obj)
try:
otherdb = obj._p_jar.db()
database_name = otherdb.database_name
except AttributeError:
otherdb = self
if self._jar.db().databases.get(database_name) is not otherdb:
raise InvalidObjectReference(
"Attempt to store an object from a foreign "
"database connection",
self._jar,
obj,
)
if self._jar.get_connection(database_name) is not obj._p_jar:
raise InvalidObjectReference(
"Attempt to store a reference to an object from "
"a separate connection to the same database or "
"multidatabase",
self._jar,
obj,
)
# OK, we have an object from another database.
# Lets make sure the object ws not *just* loaded.
if obj._p_jar._implicitlyAdding(oid):
raise InvalidObjectReference(
"A new object is reachable from multiple databases. "
"Won't try to guess which one was correct!",
self._jar,
obj,
)
klass = type(obj)
if hasattr(klass, '__getnewargs__'):
# We don't want to save newargs in object refs.
# It's possible that __getnewargs__ is degenerate and
# returns (), but we don't want to have to deghostify
# the object to find out.
# Note that this has the odd effect that, if the class has
# __getnewargs__ of its own, we'll lose the optimization
# of caching the class info.
if database_name is not None:
return ['n', (database_name, oid)]
return oid
# Note that we never get here for persistent classes.
# We'll use direct refs for normal classes.
if database_name is not None:
return ['m', (database_name, oid, klass)]
return oid, klass
