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# orm/instrumentation.py
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# Copyright (C) 2005-2025 the SQLAlchemy authors and contributors
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# <see AUTHORS file>
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#
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# This module is part of SQLAlchemy and is released under
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# the MIT License: https://www.opensource.org/licenses/mit-license.php
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# mypy: allow-untyped-defs, allow-untyped-calls
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"""Defines SQLAlchemy's system of class instrumentation.
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This module is usually not directly visible to user applications, but
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defines a large part of the ORM's interactivity.
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instrumentation.py deals with registration of end-user classes
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for state tracking. It interacts closely with state.py
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and attributes.py which establish per-instance and per-class-attribute
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instrumentation, respectively.
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The class instrumentation system can be customized on a per-class
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or global basis using the :mod:`sqlalchemy.ext.instrumentation`
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module, which provides the means to build and specify
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alternate instrumentation forms.
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.. versionchanged: 0.8
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The instrumentation extension system was moved out of the
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ORM and into the external :mod:`sqlalchemy.ext.instrumentation`
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package. When that package is imported, it installs
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itself within sqlalchemy.orm so that its more comprehensive
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resolution mechanics take effect.
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"""
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from __future__ import annotations
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from typing import Any
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from typing import Callable
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from typing import cast
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from typing import Collection
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from typing import Dict
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from typing import Generic
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from typing import Iterable
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from typing import List
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from typing import Optional
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from typing import Set
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from typing import Tuple
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from typing import Type
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from typing import TYPE_CHECKING
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from typing import TypeVar
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from typing import Union
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import weakref
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from . import base
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from . import collections
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from . import exc
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from . import interfaces
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from . import state
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from ._typing import _O
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from .attributes import _is_collection_attribute_impl
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from .. import util
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from ..event import EventTarget
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from ..util import HasMemoized
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from ..util.typing import Literal
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from ..util.typing import Protocol
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if TYPE_CHECKING:
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from ._typing import _RegistryType
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from .attributes import AttributeImpl
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from .attributes import QueryableAttribute
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from .collections import _AdaptedCollectionProtocol
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from .collections import _CollectionFactoryType
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from .decl_base import _MapperConfig
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from .events import InstanceEvents
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from .mapper import Mapper
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from .state import InstanceState
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from ..event import dispatcher
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_T = TypeVar("_T", bound=Any)
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DEL_ATTR = util.symbol("DEL_ATTR")
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class _ExpiredAttributeLoaderProto(Protocol):
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def __call__(
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self,
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state: state.InstanceState[Any],
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toload: Set[str],
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passive: base.PassiveFlag,
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) -> None: ...
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class _ManagerFactory(Protocol):
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def __call__(self, class_: Type[_O]) -> ClassManager[_O]: ...
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class ClassManager(
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HasMemoized,
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Dict[str, "QueryableAttribute[Any]"],
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Generic[_O],
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EventTarget,
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):
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"""Tracks state information at the class level."""
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dispatch: dispatcher[ClassManager[_O]]
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MANAGER_ATTR = base.DEFAULT_MANAGER_ATTR
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STATE_ATTR = base.DEFAULT_STATE_ATTR
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_state_setter = staticmethod(util.attrsetter(STATE_ATTR))
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expired_attribute_loader: _ExpiredAttributeLoaderProto
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"previously known as deferred_scalar_loader"
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init_method: Optional[Callable[..., None]]
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original_init: Optional[Callable[..., None]] = None
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factory: Optional[_ManagerFactory]
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declarative_scan: Optional[weakref.ref[_MapperConfig]] = None
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registry: _RegistryType
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if not TYPE_CHECKING:
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# starts as None during setup
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registry = None
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class_: Type[_O]
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_bases: List[ClassManager[Any]]
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@property
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@util.deprecated(
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"1.4",
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message="The ClassManager.deferred_scalar_loader attribute is now "
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"named expired_attribute_loader",
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)
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def deferred_scalar_loader(self):
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return self.expired_attribute_loader
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@deferred_scalar_loader.setter
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@util.deprecated(
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"1.4",
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message="The ClassManager.deferred_scalar_loader attribute is now "
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"named expired_attribute_loader",
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)
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def deferred_scalar_loader(self, obj):
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self.expired_attribute_loader = obj
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def __init__(self, class_):
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self.class_ = class_
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self.info = {}
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self.new_init = None
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self.local_attrs = {}
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self.originals = {}
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self._finalized = False
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self.factory = None
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self.init_method = None
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self._bases = [
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mgr
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for mgr in cast(
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"List[Optional[ClassManager[Any]]]",
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[
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opt_manager_of_class(base)
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for base in self.class_.__bases__
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if isinstance(base, type)
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],
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)
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if mgr is not None
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]
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for base_ in self._bases:
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self.update(base_)
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cast(
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"InstanceEvents", self.dispatch._events
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)._new_classmanager_instance(class_, self)
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for basecls in class_.__mro__:
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mgr = opt_manager_of_class(basecls)
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if mgr is not None:
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self.dispatch._update(mgr.dispatch)
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self.manage()
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if "__del__" in class_.__dict__:
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util.warn(
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"__del__() method on class %s will "
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"cause unreachable cycles and memory leaks, "
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"as SQLAlchemy instrumentation often creates "
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"reference cycles. Please remove this method." % class_
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)
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def _update_state(
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self,
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finalize: bool = False,
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mapper: Optional[Mapper[_O]] = None,
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registry: Optional[_RegistryType] = None,
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declarative_scan: Optional[_MapperConfig] = None,
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expired_attribute_loader: Optional[
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_ExpiredAttributeLoaderProto
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] = None,
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init_method: Optional[Callable[..., None]] = None,
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) -> None:
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if mapper:
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self.mapper = mapper #
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if registry:
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registry._add_manager(self)
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if declarative_scan:
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self.declarative_scan = weakref.ref(declarative_scan)
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if expired_attribute_loader:
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self.expired_attribute_loader = expired_attribute_loader
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if init_method:
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assert not self._finalized, (
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"class is already instrumented, "
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"init_method %s can't be applied" % init_method
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)
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self.init_method = init_method
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if not self._finalized:
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self.original_init = (
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self.init_method
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if self.init_method is not None
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and self.class_.__init__ is object.__init__
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else self.class_.__init__
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)
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if finalize and not self._finalized:
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self._finalize()
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def _finalize(self) -> None:
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if self._finalized:
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return
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self._finalized = True
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self._instrument_init()
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_instrumentation_factory.dispatch.class_instrument(self.class_)
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def __hash__(self) -> int: # type: ignore[override]
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return id(self)
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def __eq__(self, other: Any) -> bool:
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return other is self
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@property
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def is_mapped(self) -> bool:
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return "mapper" in self.__dict__
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@HasMemoized.memoized_attribute
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def _all_key_set(self):
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return frozenset(self)
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@HasMemoized.memoized_attribute
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def _collection_impl_keys(self):
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return frozenset(
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[attr.key for attr in self.values() if attr.impl.collection]
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)
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@HasMemoized.memoized_attribute
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def _scalar_loader_impls(self):
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return frozenset(
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[
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attr.impl
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for attr in self.values()
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if attr.impl.accepts_scalar_loader
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]
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)
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@HasMemoized.memoized_attribute
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def _loader_impls(self):
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return frozenset([attr.impl for attr in self.values()])
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@util.memoized_property
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def mapper(self) -> Mapper[_O]:
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# raises unless self.mapper has been assigned
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raise exc.UnmappedClassError(self.class_)
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def _all_sqla_attributes(self, exclude=None):
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"""return an iterator of all classbound attributes that are
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implement :class:`.InspectionAttr`.
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This includes :class:`.QueryableAttribute` as well as extension
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types such as :class:`.hybrid_property` and
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:class:`.AssociationProxy`.
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"""
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found: Dict[str, Any] = {}
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# constraints:
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# 1. yield keys in cls.__dict__ order
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# 2. if a subclass has the same key as a superclass, include that
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# key as part of the ordering of the superclass, because an
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# overridden key is usually installed by the mapper which is going
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# on a different ordering
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# 3. don't use getattr() as this fires off descriptors
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for supercls in self.class_.__mro__[0:-1]:
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inherits = supercls.__mro__[1]
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for key in supercls.__dict__:
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found.setdefault(key, supercls)
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if key in inherits.__dict__:
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continue
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val = found[key].__dict__[key]
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if (
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isinstance(val, interfaces.InspectionAttr)
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and val.is_attribute
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):
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yield key, val
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def _get_class_attr_mro(self, key, default=None):
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"""return an attribute on the class without tripping it."""
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for supercls in self.class_.__mro__:
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if key in supercls.__dict__:
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return supercls.__dict__[key]
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else:
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return default
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def _attr_has_impl(self, key: str) -> bool:
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"""Return True if the given attribute is fully initialized.
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i.e. has an impl.
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"""
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return key in self and self[key].impl is not None
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def _subclass_manager(self, cls: Type[_T]) -> ClassManager[_T]:
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"""Create a new ClassManager for a subclass of this ClassManager's
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class.
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This is called automatically when attributes are instrumented so that
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the attributes can be propagated to subclasses against their own
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class-local manager, without the need for mappers etc. to have already
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pre-configured managers for the full class hierarchy. Mappers
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can post-configure the auto-generated ClassManager when needed.
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"""
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return register_class(cls, finalize=False)
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def _instrument_init(self):
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self.new_init = _generate_init(self.class_, self, self.original_init)
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self.install_member("__init__", self.new_init)
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@util.memoized_property
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def _state_constructor(self) -> Type[state.InstanceState[_O]]:
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self.dispatch.first_init(self, self.class_)
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return state.InstanceState
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def manage(self):
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"""Mark this instance as the manager for its class."""
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setattr(self.class_, self.MANAGER_ATTR, self)
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@util.hybridmethod
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def manager_getter(self):
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return _default_manager_getter
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@util.hybridmethod
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def state_getter(self):
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"""Return a (instance) -> InstanceState callable.
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"state getter" callables should raise either KeyError or
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AttributeError if no InstanceState could be found for the
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instance.
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"""
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return _default_state_getter
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@util.hybridmethod
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def dict_getter(self):
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return _default_dict_getter
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def instrument_attribute(
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self,
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key: str,
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inst: QueryableAttribute[Any],
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propagated: bool = False,
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) -> None:
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if propagated:
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if key in self.local_attrs:
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return # don't override local attr with inherited attr
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else:
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self.local_attrs[key] = inst
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self.install_descriptor(key, inst)
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self._reset_memoizations()
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self[key] = inst
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for cls in self.class_.__subclasses__():
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manager = self._subclass_manager(cls)
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manager.instrument_attribute(key, inst, True)
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def subclass_managers(self, recursive):
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for cls in self.class_.__subclasses__():
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mgr = opt_manager_of_class(cls)
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if mgr is not None and mgr is not self:
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yield mgr
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if recursive:
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yield from mgr.subclass_managers(True)
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def post_configure_attribute(self, key):
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_instrumentation_factory.dispatch.attribute_instrument(
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self.class_, key, self[key]
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)
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def uninstrument_attribute(self, key, propagated=False):
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if key not in self:
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return
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if propagated:
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if key in self.local_attrs:
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return # don't get rid of local attr
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else:
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del self.local_attrs[key]
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self.uninstall_descriptor(key)
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self._reset_memoizations()
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del self[key]
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for cls in self.class_.__subclasses__():
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manager = opt_manager_of_class(cls)
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if manager:
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manager.uninstrument_attribute(key, True)
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def unregister(self) -> None:
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"""remove all instrumentation established by this ClassManager."""
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for key in list(self.originals):
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self.uninstall_member(key)
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self.mapper = None
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self.dispatch = None # type: ignore
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self.new_init = None
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self.info.clear()
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for key in list(self):
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if key in self.local_attrs:
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self.uninstrument_attribute(key)
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if self.MANAGER_ATTR in self.class_.__dict__:
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delattr(self.class_, self.MANAGER_ATTR)
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def install_descriptor(
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self, key: str, inst: QueryableAttribute[Any]
|
||||
) -> None:
|
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if key in (self.STATE_ATTR, self.MANAGER_ATTR):
|
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raise KeyError(
|
||||
"%r: requested attribute name conflicts with "
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||||
"instrumentation attribute of the same name." % key
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)
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||||
setattr(self.class_, key, inst)
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||||
|
||||
def uninstall_descriptor(self, key: str) -> None:
|
||||
delattr(self.class_, key)
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||||
|
||||
def install_member(self, key: str, implementation: Any) -> None:
|
||||
if key in (self.STATE_ATTR, self.MANAGER_ATTR):
|
||||
raise KeyError(
|
||||
"%r: requested attribute name conflicts with "
|
||||
"instrumentation attribute of the same name." % key
|
||||
)
|
||||
self.originals.setdefault(key, self.class_.__dict__.get(key, DEL_ATTR))
|
||||
setattr(self.class_, key, implementation)
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||||
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||||
def uninstall_member(self, key: str) -> None:
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||||
original = self.originals.pop(key, None)
|
||||
if original is not DEL_ATTR:
|
||||
setattr(self.class_, key, original)
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||||
else:
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||||
delattr(self.class_, key)
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||||
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||||
def instrument_collection_class(
|
||||
self, key: str, collection_class: Type[Collection[Any]]
|
||||
) -> _CollectionFactoryType:
|
||||
return collections.prepare_instrumentation(collection_class)
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||||
|
||||
def initialize_collection(
|
||||
self,
|
||||
key: str,
|
||||
state: InstanceState[_O],
|
||||
factory: _CollectionFactoryType,
|
||||
) -> Tuple[collections.CollectionAdapter, _AdaptedCollectionProtocol]:
|
||||
user_data = factory()
|
||||
impl = self.get_impl(key)
|
||||
assert _is_collection_attribute_impl(impl)
|
||||
adapter = collections.CollectionAdapter(impl, state, user_data)
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||||
return adapter, user_data
|
||||
|
||||
def is_instrumented(self, key: str, search: bool = False) -> bool:
|
||||
if search:
|
||||
return key in self
|
||||
else:
|
||||
return key in self.local_attrs
|
||||
|
||||
def get_impl(self, key: str) -> AttributeImpl:
|
||||
return self[key].impl
|
||||
|
||||
@property
|
||||
def attributes(self) -> Iterable[Any]:
|
||||
return iter(self.values())
|
||||
|
||||
# InstanceState management
|
||||
|
||||
def new_instance(self, state: Optional[InstanceState[_O]] = None) -> _O:
|
||||
# here, we would prefer _O to be bound to "object"
|
||||
# so that mypy sees that __new__ is present. currently
|
||||
# it's bound to Any as there were other problems not having
|
||||
# it that way but these can be revisited
|
||||
instance = self.class_.__new__(self.class_)
|
||||
if state is None:
|
||||
state = self._state_constructor(instance, self)
|
||||
self._state_setter(instance, state)
|
||||
return instance
|
||||
|
||||
def setup_instance(
|
||||
self, instance: _O, state: Optional[InstanceState[_O]] = None
|
||||
) -> None:
|
||||
if state is None:
|
||||
state = self._state_constructor(instance, self)
|
||||
self._state_setter(instance, state)
|
||||
|
||||
def teardown_instance(self, instance: _O) -> None:
|
||||
delattr(instance, self.STATE_ATTR)
|
||||
|
||||
def _serialize(
|
||||
self, state: InstanceState[_O], state_dict: Dict[str, Any]
|
||||
) -> _SerializeManager:
|
||||
return _SerializeManager(state, state_dict)
|
||||
|
||||
def _new_state_if_none(
|
||||
self, instance: _O
|
||||
) -> Union[Literal[False], InstanceState[_O]]:
|
||||
"""Install a default InstanceState if none is present.
|
||||
|
||||
A private convenience method used by the __init__ decorator.
|
||||
|
||||
"""
|
||||
if hasattr(instance, self.STATE_ATTR):
|
||||
return False
|
||||
elif self.class_ is not instance.__class__ and self.is_mapped:
|
||||
# this will create a new ClassManager for the
|
||||
# subclass, without a mapper. This is likely a
|
||||
# user error situation but allow the object
|
||||
# to be constructed, so that it is usable
|
||||
# in a non-ORM context at least.
|
||||
return self._subclass_manager(
|
||||
instance.__class__
|
||||
)._new_state_if_none(instance)
|
||||
else:
|
||||
state = self._state_constructor(instance, self)
|
||||
self._state_setter(instance, state)
|
||||
return state
|
||||
|
||||
def has_state(self, instance: _O) -> bool:
|
||||
return hasattr(instance, self.STATE_ATTR)
|
||||
|
||||
def has_parent(
|
||||
self, state: InstanceState[_O], key: str, optimistic: bool = False
|
||||
) -> bool:
|
||||
"""TODO"""
|
||||
return self.get_impl(key).hasparent(state, optimistic=optimistic)
|
||||
|
||||
def __bool__(self) -> bool:
|
||||
"""All ClassManagers are non-zero regardless of attribute state."""
|
||||
return True
|
||||
|
||||
def __repr__(self) -> str:
|
||||
return "<%s of %r at %x>" % (
|
||||
self.__class__.__name__,
|
||||
self.class_,
|
||||
id(self),
|
||||
)
|
||||
|
||||
|
||||
class _SerializeManager:
|
||||
"""Provide serialization of a :class:`.ClassManager`.
|
||||
|
||||
The :class:`.InstanceState` uses ``__init__()`` on serialize
|
||||
and ``__call__()`` on deserialize.
|
||||
|
||||
"""
|
||||
|
||||
def __init__(self, state: state.InstanceState[Any], d: Dict[str, Any]):
|
||||
self.class_ = state.class_
|
||||
manager = state.manager
|
||||
manager.dispatch.pickle(state, d)
|
||||
|
||||
def __call__(self, state, inst, state_dict):
|
||||
state.manager = manager = opt_manager_of_class(self.class_)
|
||||
if manager is None:
|
||||
raise exc.UnmappedInstanceError(
|
||||
inst,
|
||||
"Cannot deserialize object of type %r - "
|
||||
"no mapper() has "
|
||||
"been configured for this class within the current "
|
||||
"Python process!" % self.class_,
|
||||
)
|
||||
elif manager.is_mapped and not manager.mapper.configured:
|
||||
manager.mapper._check_configure()
|
||||
|
||||
# setup _sa_instance_state ahead of time so that
|
||||
# unpickle events can access the object normally.
|
||||
# see [ticket:2362]
|
||||
if inst is not None:
|
||||
manager.setup_instance(inst, state)
|
||||
manager.dispatch.unpickle(state, state_dict)
|
||||
|
||||
|
||||
class InstrumentationFactory(EventTarget):
|
||||
"""Factory for new ClassManager instances."""
|
||||
|
||||
dispatch: dispatcher[InstrumentationFactory]
|
||||
|
||||
def create_manager_for_cls(self, class_: Type[_O]) -> ClassManager[_O]:
|
||||
assert class_ is not None
|
||||
assert opt_manager_of_class(class_) is None
|
||||
|
||||
# give a more complicated subclass
|
||||
# a chance to do what it wants here
|
||||
manager, factory = self._locate_extended_factory(class_)
|
||||
|
||||
if factory is None:
|
||||
factory = ClassManager
|
||||
manager = ClassManager(class_)
|
||||
else:
|
||||
assert manager is not None
|
||||
|
||||
self._check_conflicts(class_, factory)
|
||||
|
||||
manager.factory = factory
|
||||
|
||||
return manager
|
||||
|
||||
def _locate_extended_factory(
|
||||
self, class_: Type[_O]
|
||||
) -> Tuple[Optional[ClassManager[_O]], Optional[_ManagerFactory]]:
|
||||
"""Overridden by a subclass to do an extended lookup."""
|
||||
return None, None
|
||||
|
||||
def _check_conflicts(
|
||||
self, class_: Type[_O], factory: Callable[[Type[_O]], ClassManager[_O]]
|
||||
) -> None:
|
||||
"""Overridden by a subclass to test for conflicting factories."""
|
||||
|
||||
def unregister(self, class_: Type[_O]) -> None:
|
||||
manager = manager_of_class(class_)
|
||||
manager.unregister()
|
||||
self.dispatch.class_uninstrument(class_)
|
||||
|
||||
|
||||
# this attribute is replaced by sqlalchemy.ext.instrumentation
|
||||
# when imported.
|
||||
_instrumentation_factory = InstrumentationFactory()
|
||||
|
||||
# these attributes are replaced by sqlalchemy.ext.instrumentation
|
||||
# when a non-standard InstrumentationManager class is first
|
||||
# used to instrument a class.
|
||||
instance_state = _default_state_getter = base.instance_state
|
||||
|
||||
instance_dict = _default_dict_getter = base.instance_dict
|
||||
|
||||
manager_of_class = _default_manager_getter = base.manager_of_class
|
||||
opt_manager_of_class = _default_opt_manager_getter = base.opt_manager_of_class
|
||||
|
||||
|
||||
def register_class(
|
||||
class_: Type[_O],
|
||||
finalize: bool = True,
|
||||
mapper: Optional[Mapper[_O]] = None,
|
||||
registry: Optional[_RegistryType] = None,
|
||||
declarative_scan: Optional[_MapperConfig] = None,
|
||||
expired_attribute_loader: Optional[_ExpiredAttributeLoaderProto] = None,
|
||||
init_method: Optional[Callable[..., None]] = None,
|
||||
) -> ClassManager[_O]:
|
||||
"""Register class instrumentation.
|
||||
|
||||
Returns the existing or newly created class manager.
|
||||
|
||||
"""
|
||||
|
||||
manager = opt_manager_of_class(class_)
|
||||
if manager is None:
|
||||
manager = _instrumentation_factory.create_manager_for_cls(class_)
|
||||
manager._update_state(
|
||||
mapper=mapper,
|
||||
registry=registry,
|
||||
declarative_scan=declarative_scan,
|
||||
expired_attribute_loader=expired_attribute_loader,
|
||||
init_method=init_method,
|
||||
finalize=finalize,
|
||||
)
|
||||
|
||||
return manager
|
||||
|
||||
|
||||
def unregister_class(class_):
|
||||
"""Unregister class instrumentation."""
|
||||
|
||||
_instrumentation_factory.unregister(class_)
|
||||
|
||||
|
||||
def is_instrumented(instance, key):
|
||||
"""Return True if the given attribute on the given instance is
|
||||
instrumented by the attributes package.
|
||||
|
||||
This function may be used regardless of instrumentation
|
||||
applied directly to the class, i.e. no descriptors are required.
|
||||
|
||||
"""
|
||||
return manager_of_class(instance.__class__).is_instrumented(
|
||||
key, search=True
|
||||
)
|
||||
|
||||
|
||||
def _generate_init(class_, class_manager, original_init):
|
||||
"""Build an __init__ decorator that triggers ClassManager events."""
|
||||
|
||||
# TODO: we should use the ClassManager's notion of the
|
||||
# original '__init__' method, once ClassManager is fixed
|
||||
# to always reference that.
|
||||
|
||||
if original_init is None:
|
||||
original_init = class_.__init__
|
||||
|
||||
# Go through some effort here and don't change the user's __init__
|
||||
# calling signature, including the unlikely case that it has
|
||||
# a return value.
|
||||
# FIXME: need to juggle local names to avoid constructor argument
|
||||
# clashes.
|
||||
func_body = """\
|
||||
def __init__(%(apply_pos)s):
|
||||
new_state = class_manager._new_state_if_none(%(self_arg)s)
|
||||
if new_state:
|
||||
return new_state._initialize_instance(%(apply_kw)s)
|
||||
else:
|
||||
return original_init(%(apply_kw)s)
|
||||
"""
|
||||
func_vars = util.format_argspec_init(original_init, grouped=False)
|
||||
func_text = func_body % func_vars
|
||||
|
||||
func_defaults = getattr(original_init, "__defaults__", None)
|
||||
func_kw_defaults = getattr(original_init, "__kwdefaults__", None)
|
||||
|
||||
env = locals().copy()
|
||||
env["__name__"] = __name__
|
||||
exec(func_text, env)
|
||||
__init__ = env["__init__"]
|
||||
__init__.__doc__ = original_init.__doc__
|
||||
__init__._sa_original_init = original_init
|
||||
|
||||
if func_defaults:
|
||||
__init__.__defaults__ = func_defaults
|
||||
if func_kw_defaults:
|
||||
__init__.__kwdefaults__ = func_kw_defaults
|
||||
|
||||
return __init__
|
||||
Reference in New Issue
Block a user