Current File : //opt/hc_python/lib64/python3.8/site-packages/sqlalchemy/orm/state.py
# orm/state.py
# Copyright (C) 2005-2024 the SQLAlchemy authors and contributors
# <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: https://www.opensource.org/licenses/mit-license.php
"""Defines instrumentation of instances.
This module is usually not directly visible to user applications, but
defines a large part of the ORM's interactivity.
"""
from __future__ import annotations
from typing import Any
from typing import Callable
from typing import Dict
from typing import Generic
from typing import Iterable
from typing import Optional
from typing import Set
from typing import Tuple
from typing import TYPE_CHECKING
from typing import Union
import weakref
from . import base
from . import exc as orm_exc
from . import interfaces
from ._typing import _O
from ._typing import is_collection_impl
from .base import ATTR_WAS_SET
from .base import INIT_OK
from .base import LoaderCallableStatus
from .base import NEVER_SET
from .base import NO_VALUE
from .base import PASSIVE_NO_INITIALIZE
from .base import PASSIVE_NO_RESULT
from .base import PASSIVE_OFF
from .base import SQL_OK
from .path_registry import PathRegistry
from .. import exc as sa_exc
from .. import inspection
from .. import util
from ..util.typing import Literal
from ..util.typing import Protocol
if TYPE_CHECKING:
from ._typing import _IdentityKeyType
from ._typing import _InstanceDict
from ._typing import _LoaderCallable
from .attributes import AttributeImpl
from .attributes import History
from .base import PassiveFlag
from .collections import _AdaptedCollectionProtocol
from .identity import IdentityMap
from .instrumentation import ClassManager
from .interfaces import ORMOption
from .mapper import Mapper
from .session import Session
from ..engine import Row
from ..ext.asyncio.session import async_session as _async_provider
from ..ext.asyncio.session import AsyncSession
if TYPE_CHECKING:
_sessions: weakref.WeakValueDictionary[int, Session]
else:
# late-populated by session.py
_sessions = None
if not TYPE_CHECKING:
# optionally late-provided by sqlalchemy.ext.asyncio.session
_async_provider = None # noqa
class _InstanceDictProto(Protocol):
def __call__(self) -> Optional[IdentityMap]: ...
class _InstallLoaderCallableProto(Protocol[_O]):
"""used at result loading time to install a _LoaderCallable callable
upon a specific InstanceState, which will be used to populate an
attribute when that attribute is accessed.
Concrete examples are per-instance deferred column loaders and
relationship lazy loaders.
"""
def __call__(
self, state: InstanceState[_O], dict_: _InstanceDict, row: Row[Any]
) -> None: ...
@inspection._self_inspects
class InstanceState(interfaces.InspectionAttrInfo, Generic[_O]):
"""Tracks state information at the instance level.
The :class:`.InstanceState` is a key object used by the
SQLAlchemy ORM in order to track the state of an object;
it is created the moment an object is instantiated, typically
as a result of :term:`instrumentation` which SQLAlchemy applies
to the ``__init__()`` method of the class.
:class:`.InstanceState` is also a semi-public object,
available for runtime inspection as to the state of a
mapped instance, including information such as its current
status within a particular :class:`.Session` and details
about data on individual attributes. The public API
in order to acquire a :class:`.InstanceState` object
is to use the :func:`_sa.inspect` system::
>>> from sqlalchemy import inspect
>>> insp = inspect(some_mapped_object)
>>> insp.attrs.nickname.history
History(added=['new nickname'], unchanged=(), deleted=['nickname'])
.. seealso::
:ref:`orm_mapper_inspection_instancestate`
"""
__slots__ = (
"__dict__",
"__weakref__",
"class_",
"manager",
"obj",
"committed_state",
"expired_attributes",
)
manager: ClassManager[_O]
session_id: Optional[int] = None
key: Optional[_IdentityKeyType[_O]] = None
runid: Optional[int] = None
load_options: Tuple[ORMOption, ...] = ()
load_path: PathRegistry = PathRegistry.root
insert_order: Optional[int] = None
_strong_obj: Optional[object] = None
obj: weakref.ref[_O]
committed_state: Dict[str, Any]
modified: bool = False
"""When ``True`` the object was modified."""
expired: bool = False
"""When ``True`` the object is :term:`expired`.
.. seealso::
:ref:`session_expire`
"""
_deleted: bool = False
_load_pending: bool = False
_orphaned_outside_of_session: bool = False
is_instance: bool = True
identity_token: object = None
_last_known_values: Optional[Dict[str, Any]] = None
_instance_dict: _InstanceDictProto
"""A weak reference, or in the default case a plain callable, that
returns a reference to the current :class:`.IdentityMap`, if any.
"""
if not TYPE_CHECKING:
def _instance_dict(self):
"""default 'weak reference' for _instance_dict"""
return None
expired_attributes: Set[str]
"""The set of keys which are 'expired' to be loaded by
the manager's deferred scalar loader, assuming no pending
changes.
See also the ``unmodified`` collection which is intersected
against this set when a refresh operation occurs.
"""
callables: Dict[str, Callable[[InstanceState[_O], PassiveFlag], Any]]
"""A namespace where a per-state loader callable can be associated.
In SQLAlchemy 1.0, this is only used for lazy loaders / deferred
loaders that were set up via query option.
Previously, callables was used also to indicate expired attributes
by storing a link to the InstanceState itself in this dictionary.
This role is now handled by the expired_attributes set.
"""
if not TYPE_CHECKING:
callables = util.EMPTY_DICT
def __init__(self, obj: _O, manager: ClassManager[_O]):
self.class_ = obj.__class__
self.manager = manager
self.obj = weakref.ref(obj, self._cleanup)
self.committed_state = {}
self.expired_attributes = set()
@util.memoized_property
def attrs(self) -> util.ReadOnlyProperties[AttributeState]:
"""Return a namespace representing each attribute on
the mapped object, including its current value
and history.
The returned object is an instance of :class:`.AttributeState`.
This object allows inspection of the current data
within an attribute as well as attribute history
since the last flush.
"""
return util.ReadOnlyProperties(
{key: AttributeState(self, key) for key in self.manager}
)
@property
def transient(self) -> bool:
"""Return ``True`` if the object is :term:`transient`.
.. seealso::
:ref:`session_object_states`
"""
return self.key is None and not self._attached
@property
def pending(self) -> bool:
"""Return ``True`` if the object is :term:`pending`.
.. seealso::
:ref:`session_object_states`
"""
return self.key is None and self._attached
@property
def deleted(self) -> bool:
"""Return ``True`` if the object is :term:`deleted`.
An object that is in the deleted state is guaranteed to
not be within the :attr:`.Session.identity_map` of its parent
:class:`.Session`; however if the session's transaction is rolled
back, the object will be restored to the persistent state and
the identity map.
.. note::
The :attr:`.InstanceState.deleted` attribute refers to a specific
state of the object that occurs between the "persistent" and
"detached" states; once the object is :term:`detached`, the
:attr:`.InstanceState.deleted` attribute **no longer returns
True**; in order to detect that a state was deleted, regardless
of whether or not the object is associated with a
:class:`.Session`, use the :attr:`.InstanceState.was_deleted`
accessor.
.. versionadded: 1.1
.. seealso::
:ref:`session_object_states`
"""
return self.key is not None and self._attached and self._deleted
@property
def was_deleted(self) -> bool:
"""Return True if this object is or was previously in the
"deleted" state and has not been reverted to persistent.
This flag returns True once the object was deleted in flush.
When the object is expunged from the session either explicitly
or via transaction commit and enters the "detached" state,
this flag will continue to report True.
.. seealso::
:attr:`.InstanceState.deleted` - refers to the "deleted" state
:func:`.orm.util.was_deleted` - standalone function
:ref:`session_object_states`
"""
return self._deleted
@property
def persistent(self) -> bool:
"""Return ``True`` if the object is :term:`persistent`.
An object that is in the persistent state is guaranteed to
be within the :attr:`.Session.identity_map` of its parent
:class:`.Session`.
.. seealso::
:ref:`session_object_states`
"""
return self.key is not None and self._attached and not self._deleted
@property
def detached(self) -> bool:
"""Return ``True`` if the object is :term:`detached`.
.. seealso::
:ref:`session_object_states`
"""
return self.key is not None and not self._attached
@util.non_memoized_property
@util.preload_module("sqlalchemy.orm.session")
def _attached(self) -> bool:
return (
self.session_id is not None
and self.session_id in util.preloaded.orm_session._sessions
)
def _track_last_known_value(self, key: str) -> None:
"""Track the last known value of a particular key after expiration
operations.
.. versionadded:: 1.3
"""
lkv = self._last_known_values
if lkv is None:
self._last_known_values = lkv = {}
if key not in lkv:
lkv[key] = NO_VALUE
@property
def session(self) -> Optional[Session]:
"""Return the owning :class:`.Session` for this instance,
or ``None`` if none available.
Note that the result here can in some cases be *different*
from that of ``obj in session``; an object that's been deleted
will report as not ``in session``, however if the transaction is
still in progress, this attribute will still refer to that session.
Only when the transaction is completed does the object become
fully detached under normal circumstances.
.. seealso::
:attr:`_orm.InstanceState.async_session`
"""
if self.session_id:
try:
return _sessions[self.session_id]
except KeyError:
pass
return None
@property
def async_session(self) -> Optional[AsyncSession]:
"""Return the owning :class:`_asyncio.AsyncSession` for this instance,
or ``None`` if none available.
This attribute is only non-None when the :mod:`sqlalchemy.ext.asyncio`
API is in use for this ORM object. The returned
:class:`_asyncio.AsyncSession` object will be a proxy for the
:class:`_orm.Session` object that would be returned from the
:attr:`_orm.InstanceState.session` attribute for this
:class:`_orm.InstanceState`.
.. versionadded:: 1.4.18
.. seealso::
:ref:`asyncio_toplevel`
"""
if _async_provider is None:
return None
sess = self.session
if sess is not None:
return _async_provider(sess)
else:
return None
@property
def object(self) -> Optional[_O]:
"""Return the mapped object represented by this
:class:`.InstanceState`.
Returns None if the object has been garbage collected
"""
return self.obj()
@property
def identity(self) -> Optional[Tuple[Any, ...]]:
"""Return the mapped identity of the mapped object.
This is the primary key identity as persisted by the ORM
which can always be passed directly to
:meth:`_query.Query.get`.
Returns ``None`` if the object has no primary key identity.
.. note::
An object which is :term:`transient` or :term:`pending`
does **not** have a mapped identity until it is flushed,
even if its attributes include primary key values.
"""
if self.key is None:
return None
else:
return self.key[1]
@property
def identity_key(self) -> Optional[_IdentityKeyType[_O]]:
"""Return the identity key for the mapped object.
This is the key used to locate the object within
the :attr:`.Session.identity_map` mapping. It contains
the identity as returned by :attr:`.identity` within it.
"""
return self.key
@util.memoized_property
def parents(self) -> Dict[int, Union[Literal[False], InstanceState[Any]]]:
return {}
@util.memoized_property
def _pending_mutations(self) -> Dict[str, PendingCollection]:
return {}
@util.memoized_property
def _empty_collections(self) -> Dict[str, _AdaptedCollectionProtocol]:
return {}
@util.memoized_property
def mapper(self) -> Mapper[_O]:
"""Return the :class:`_orm.Mapper` used for this mapped object."""
return self.manager.mapper
@property
def has_identity(self) -> bool:
"""Return ``True`` if this object has an identity key.
This should always have the same value as the
expression ``state.persistent`` or ``state.detached``.
"""
return bool(self.key)
@classmethod
def _detach_states(
self,
states: Iterable[InstanceState[_O]],
session: Session,
to_transient: bool = False,
) -> None:
persistent_to_detached = (
session.dispatch.persistent_to_detached or None
)
deleted_to_detached = session.dispatch.deleted_to_detached or None
pending_to_transient = session.dispatch.pending_to_transient or None
persistent_to_transient = (
session.dispatch.persistent_to_transient or None
)
for state in states:
deleted = state._deleted
pending = state.key is None
persistent = not pending and not deleted
state.session_id = None
if to_transient and state.key:
del state.key
if persistent:
if to_transient:
if persistent_to_transient is not None:
persistent_to_transient(session, state)
elif persistent_to_detached is not None:
persistent_to_detached(session, state)
elif deleted and deleted_to_detached is not None:
deleted_to_detached(session, state)
elif pending and pending_to_transient is not None:
pending_to_transient(session, state)
state._strong_obj = None
def _detach(self, session: Optional[Session] = None) -> None:
if session:
InstanceState._detach_states([self], session)
else:
self.session_id = self._strong_obj = None
def _dispose(self) -> None:
# used by the test suite, apparently
self._detach()
def _cleanup(self, ref: weakref.ref[_O]) -> None:
"""Weakref callback cleanup.
This callable cleans out the state when it is being garbage
collected.
this _cleanup **assumes** that there are no strong refs to us!
Will not work otherwise!
"""
# Python builtins become undefined during interpreter shutdown.
# Guard against exceptions during this phase, as the method cannot
# proceed in any case if builtins have been undefined.
if dict is None:
return
instance_dict = self._instance_dict()
if instance_dict is not None:
instance_dict._fast_discard(self)
del self._instance_dict
# we can't possibly be in instance_dict._modified
# b.c. this is weakref cleanup only, that set
# is strong referencing!
# assert self not in instance_dict._modified
self.session_id = self._strong_obj = None
@property
def dict(self) -> _InstanceDict:
"""Return the instance dict used by the object.
Under normal circumstances, this is always synonymous
with the ``__dict__`` attribute of the mapped object,
unless an alternative instrumentation system has been
configured.
In the case that the actual object has been garbage
collected, this accessor returns a blank dictionary.
"""
o = self.obj()
if o is not None:
return base.instance_dict(o)
else:
return {}
def _initialize_instance(*mixed: Any, **kwargs: Any) -> None:
self, instance, args = mixed[0], mixed[1], mixed[2:] # noqa
manager = self.manager
manager.dispatch.init(self, args, kwargs)
try:
manager.original_init(*mixed[1:], **kwargs)
except:
with util.safe_reraise():
manager.dispatch.init_failure(self, args, kwargs)
def get_history(self, key: str, passive: PassiveFlag) -> History:
return self.manager[key].impl.get_history(self, self.dict, passive)
def get_impl(self, key: str) -> AttributeImpl:
return self.manager[key].impl
def _get_pending_mutation(self, key: str) -> PendingCollection:
if key not in self._pending_mutations:
self._pending_mutations[key] = PendingCollection()
return self._pending_mutations[key]
def __getstate__(self) -> Dict[str, Any]:
state_dict: Dict[str, Any] = {
"instance": self.obj(),
"class_": self.class_,
"committed_state": self.committed_state,
"expired_attributes": self.expired_attributes,
}
state_dict.update(
(k, self.__dict__[k])
for k in (
"_pending_mutations",
"modified",
"expired",
"callables",
"key",
"parents",
"load_options",
"class_",
"expired_attributes",
"info",
)
if k in self.__dict__
)
if self.load_path:
state_dict["load_path"] = self.load_path.serialize()
state_dict["manager"] = self.manager._serialize(self, state_dict)
return state_dict
def __setstate__(self, state_dict: Dict[str, Any]) -> None:
inst = state_dict["instance"]
if inst is not None:
self.obj = weakref.ref(inst, self._cleanup)
self.class_ = inst.__class__
else:
self.obj = lambda: None # type: ignore
self.class_ = state_dict["class_"]
self.committed_state = state_dict.get("committed_state", {})
self._pending_mutations = state_dict.get("_pending_mutations", {})
self.parents = state_dict.get("parents", {})
self.modified = state_dict.get("modified", False)
self.expired = state_dict.get("expired", False)
if "info" in state_dict:
self.info.update(state_dict["info"])
if "callables" in state_dict:
self.callables = state_dict["callables"]
self.expired_attributes = state_dict["expired_attributes"]
else:
if "expired_attributes" in state_dict:
self.expired_attributes = state_dict["expired_attributes"]
else:
self.expired_attributes = set()
self.__dict__.update(
[
(k, state_dict[k])
for k in ("key", "load_options")
if k in state_dict
]
)
if self.key:
self.identity_token = self.key[2]
if "load_path" in state_dict:
self.load_path = PathRegistry.deserialize(state_dict["load_path"])
state_dict["manager"](self, inst, state_dict)
def _reset(self, dict_: _InstanceDict, key: str) -> None:
"""Remove the given attribute and any
callables associated with it."""
old = dict_.pop(key, None)
manager_impl = self.manager[key].impl
if old is not None and is_collection_impl(manager_impl):
manager_impl._invalidate_collection(old)
self.expired_attributes.discard(key)
if self.callables:
self.callables.pop(key, None)
def _copy_callables(self, from_: InstanceState[Any]) -> None:
if "callables" in from_.__dict__:
self.callables = dict(from_.callables)
@classmethod
def _instance_level_callable_processor(
cls, manager: ClassManager[_O], fn: _LoaderCallable, key: Any
) -> _InstallLoaderCallableProto[_O]:
impl = manager[key].impl
if is_collection_impl(impl):
fixed_impl = impl
def _set_callable(
state: InstanceState[_O], dict_: _InstanceDict, row: Row[Any]
) -> None:
if "callables" not in state.__dict__:
state.callables = {}
old = dict_.pop(key, None)
if old is not None:
fixed_impl._invalidate_collection(old)
state.callables[key] = fn
else:
def _set_callable(
state: InstanceState[_O], dict_: _InstanceDict, row: Row[Any]
) -> None:
if "callables" not in state.__dict__:
state.callables = {}
state.callables[key] = fn
return _set_callable
def _expire(
self, dict_: _InstanceDict, modified_set: Set[InstanceState[Any]]
) -> None:
self.expired = True
if self.modified:
modified_set.discard(self)
self.committed_state.clear()
self.modified = False
self._strong_obj = None
if "_pending_mutations" in self.__dict__:
del self.__dict__["_pending_mutations"]
if "parents" in self.__dict__:
del self.__dict__["parents"]
self.expired_attributes.update(
[impl.key for impl in self.manager._loader_impls]
)
if self.callables:
# the per state loader callables we can remove here are
# LoadDeferredColumns, which undefers a column at the instance
# level that is mapped with deferred, and LoadLazyAttribute,
# which lazy loads a relationship at the instance level that
# is mapped with "noload" or perhaps "immediateload".
# Before 1.4, only column-based
# attributes could be considered to be "expired", so here they
# were the only ones "unexpired", which means to make them deferred
# again. For the moment, as of 1.4 we also apply the same
# treatment relationships now, that is, an instance level lazy
# loader is reset in the same way as a column loader.
for k in self.expired_attributes.intersection(self.callables):
del self.callables[k]
for k in self.manager._collection_impl_keys.intersection(dict_):
collection = dict_.pop(k)
collection._sa_adapter.invalidated = True
if self._last_known_values:
self._last_known_values.update(
{k: dict_[k] for k in self._last_known_values if k in dict_}
)
for key in self.manager._all_key_set.intersection(dict_):
del dict_[key]
self.manager.dispatch.expire(self, None)
def _expire_attributes(
self,
dict_: _InstanceDict,
attribute_names: Iterable[str],
no_loader: bool = False,
) -> None:
pending = self.__dict__.get("_pending_mutations", None)
callables = self.callables
for key in attribute_names:
impl = self.manager[key].impl
if impl.accepts_scalar_loader:
if no_loader and (impl.callable_ or key in callables):
continue
self.expired_attributes.add(key)
if callables and key in callables:
del callables[key]
old = dict_.pop(key, NO_VALUE)
if is_collection_impl(impl) and old is not NO_VALUE:
impl._invalidate_collection(old)
lkv = self._last_known_values
if lkv is not None and key in lkv and old is not NO_VALUE:
lkv[key] = old
self.committed_state.pop(key, None)
if pending:
pending.pop(key, None)
self.manager.dispatch.expire(self, attribute_names)
def _load_expired(
self, state: InstanceState[_O], passive: PassiveFlag
) -> LoaderCallableStatus:
"""__call__ allows the InstanceState to act as a deferred
callable for loading expired attributes, which is also
serializable (picklable).
"""
if not passive & SQL_OK:
return PASSIVE_NO_RESULT
toload = self.expired_attributes.intersection(self.unmodified)
toload = toload.difference(
attr
for attr in toload
if not self.manager[attr].impl.load_on_unexpire
)
self.manager.expired_attribute_loader(self, toload, passive)
# if the loader failed, or this
# instance state didn't have an identity,
# the attributes still might be in the callables
# dict. ensure they are removed.
self.expired_attributes.clear()
return ATTR_WAS_SET
@property
def unmodified(self) -> Set[str]:
"""Return the set of keys which have no uncommitted changes"""
return set(self.manager).difference(self.committed_state)
def unmodified_intersection(self, keys: Iterable[str]) -> Set[str]:
"""Return self.unmodified.intersection(keys)."""
return (
set(keys)
.intersection(self.manager)
.difference(self.committed_state)
)
@property
def unloaded(self) -> Set[str]:
"""Return the set of keys which do not have a loaded value.
This includes expired attributes and any other attribute that was never
populated or modified.
"""
return (
set(self.manager)
.difference(self.committed_state)
.difference(self.dict)
)
@property
@util.deprecated(
"2.0",
"The :attr:`.InstanceState.unloaded_expirable` attribute is "
"deprecated. Please use :attr:`.InstanceState.unloaded`.",
)
def unloaded_expirable(self) -> Set[str]:
"""Synonymous with :attr:`.InstanceState.unloaded`.
This attribute was added as an implementation-specific detail at some
point and should be considered to be private.
"""
return self.unloaded
@property
def _unloaded_non_object(self) -> Set[str]:
return self.unloaded.intersection(
attr
for attr in self.manager
if self.manager[attr].impl.accepts_scalar_loader
)
def _modified_event(
self,
dict_: _InstanceDict,
attr: Optional[AttributeImpl],
previous: Any,
collection: bool = False,
is_userland: bool = False,
) -> None:
if attr:
if not attr.send_modified_events:
return
if is_userland and attr.key not in dict_:
raise sa_exc.InvalidRequestError(
"Can't flag attribute '%s' modified; it's not present in "
"the object state" % attr.key
)
if attr.key not in self.committed_state or is_userland:
if collection:
if TYPE_CHECKING:
assert is_collection_impl(attr)
if previous is NEVER_SET:
if attr.key in dict_:
previous = dict_[attr.key]
if previous not in (None, NO_VALUE, NEVER_SET):
previous = attr.copy(previous)
self.committed_state[attr.key] = previous
lkv = self._last_known_values
if lkv is not None and attr.key in lkv:
lkv[attr.key] = NO_VALUE
# assert self._strong_obj is None or self.modified
if (self.session_id and self._strong_obj is None) or not self.modified:
self.modified = True
instance_dict = self._instance_dict()
if instance_dict:
has_modified = bool(instance_dict._modified)
instance_dict._modified.add(self)
else:
has_modified = False
# only create _strong_obj link if attached
# to a session
inst = self.obj()
if self.session_id:
self._strong_obj = inst
# if identity map already had modified objects,
# assume autobegin already occurred, else check
# for autobegin
if not has_modified:
# inline of autobegin, to ensure session transaction
# snapshot is established
try:
session = _sessions[self.session_id]
except KeyError:
pass
else:
if session._transaction is None:
session._autobegin_t()
if inst is None and attr:
raise orm_exc.ObjectDereferencedError(
"Can't emit change event for attribute '%s' - "
"parent object of type %s has been garbage "
"collected."
% (self.manager[attr.key], base.state_class_str(self))
)
def _commit(self, dict_: _InstanceDict, keys: Iterable[str]) -> None:
"""Commit attributes.
This is used by a partial-attribute load operation to mark committed
those attributes which were refreshed from the database.
Attributes marked as "expired" can potentially remain "expired" after
this step if a value was not populated in state.dict.
"""
for key in keys:
self.committed_state.pop(key, None)
self.expired = False
self.expired_attributes.difference_update(
set(keys).intersection(dict_)
)
# the per-keys commit removes object-level callables,
# while that of commit_all does not. it's not clear
# if this behavior has a clear rationale, however tests do
# ensure this is what it does.
if self.callables:
for key in (
set(self.callables).intersection(keys).intersection(dict_)
):
del self.callables[key]
def _commit_all(
self, dict_: _InstanceDict, instance_dict: Optional[IdentityMap] = None
) -> None:
"""commit all attributes unconditionally.
This is used after a flush() or a full load/refresh
to remove all pending state from the instance.
- all attributes are marked as "committed"
- the "strong dirty reference" is removed
- the "modified" flag is set to False
- any "expired" markers for scalar attributes loaded are removed.
- lazy load callables for objects / collections *stay*
Attributes marked as "expired" can potentially remain
"expired" after this step if a value was not populated in state.dict.
"""
self._commit_all_states([(self, dict_)], instance_dict)
@classmethod
def _commit_all_states(
self,
iter_: Iterable[Tuple[InstanceState[Any], _InstanceDict]],
instance_dict: Optional[IdentityMap] = None,
) -> None:
"""Mass / highly inlined version of commit_all()."""
for state, dict_ in iter_:
state_dict = state.__dict__
state.committed_state.clear()
if "_pending_mutations" in state_dict:
del state_dict["_pending_mutations"]
state.expired_attributes.difference_update(dict_)
if instance_dict and state.modified:
instance_dict._modified.discard(state)
state.modified = state.expired = False
state._strong_obj = None
class AttributeState:
"""Provide an inspection interface corresponding
to a particular attribute on a particular mapped object.
The :class:`.AttributeState` object is accessed
via the :attr:`.InstanceState.attrs` collection
of a particular :class:`.InstanceState`::
from sqlalchemy import inspect
insp = inspect(some_mapped_object)
attr_state = insp.attrs.some_attribute
"""
__slots__ = ("state", "key")
state: InstanceState[Any]
key: str
def __init__(self, state: InstanceState[Any], key: str):
self.state = state
self.key = key
@property
def loaded_value(self) -> Any:
"""The current value of this attribute as loaded from the database.
If the value has not been loaded, or is otherwise not present
in the object's dictionary, returns NO_VALUE.
"""
return self.state.dict.get(self.key, NO_VALUE)
@property
def value(self) -> Any:
"""Return the value of this attribute.
This operation is equivalent to accessing the object's
attribute directly or via ``getattr()``, and will fire
off any pending loader callables if needed.
"""
return self.state.manager[self.key].__get__(
self.state.obj(), self.state.class_
)
@property
def history(self) -> History:
"""Return the current **pre-flush** change history for
this attribute, via the :class:`.History` interface.
This method will **not** emit loader callables if the value of the
attribute is unloaded.
.. note::
The attribute history system tracks changes on a **per flush
basis**. Each time the :class:`.Session` is flushed, the history
of each attribute is reset to empty. The :class:`.Session` by
default autoflushes each time a :class:`_query.Query` is invoked.
For
options on how to control this, see :ref:`session_flushing`.
.. seealso::
:meth:`.AttributeState.load_history` - retrieve history
using loader callables if the value is not locally present.
:func:`.attributes.get_history` - underlying function
"""
return self.state.get_history(self.key, PASSIVE_NO_INITIALIZE)
def load_history(self) -> History:
"""Return the current **pre-flush** change history for
this attribute, via the :class:`.History` interface.
This method **will** emit loader callables if the value of the
attribute is unloaded.
.. note::
The attribute history system tracks changes on a **per flush
basis**. Each time the :class:`.Session` is flushed, the history
of each attribute is reset to empty. The :class:`.Session` by
default autoflushes each time a :class:`_query.Query` is invoked.
For
options on how to control this, see :ref:`session_flushing`.
.. seealso::
:attr:`.AttributeState.history`
:func:`.attributes.get_history` - underlying function
"""
return self.state.get_history(self.key, PASSIVE_OFF ^ INIT_OK)
class PendingCollection:
"""A writable placeholder for an unloaded collection.
Stores items appended to and removed from a collection that has not yet
been loaded. When the collection is loaded, the changes stored in
PendingCollection are applied to it to produce the final result.
"""
__slots__ = ("deleted_items", "added_items")
deleted_items: util.IdentitySet
added_items: util.OrderedIdentitySet
def __init__(self) -> None:
self.deleted_items = util.IdentitySet()
self.added_items = util.OrderedIdentitySet()
def merge_with_history(self, history: History) -> History:
return history._merge(self.added_items, self.deleted_items)
def append(self, value: Any) -> None:
if value in self.deleted_items:
self.deleted_items.remove(value)
else:
self.added_items.add(value)
def remove(self, value: Any) -> None:
if value in self.added_items:
self.added_items.remove(value)
else:
self.deleted_items.add(value)
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