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1# orm/base.py
2# Copyright (C) 2005-2025 the SQLAlchemy authors and contributors
3# <see AUTHORS file>
4#
5# This module is part of SQLAlchemy and is released under
6# the MIT License: https://www.opensource.org/licenses/mit-license.php
8"""Constants and rudimental functions used throughout the ORM."""
10from __future__ import annotations
12from enum import Enum
13import operator
14import typing
15from typing import Any
16from typing import Callable
17from typing import Dict
18from typing import Generic
19from typing import Literal
20from typing import no_type_check
21from typing import Optional
22from typing import overload
23from typing import Tuple
24from typing import Type
25from typing import TYPE_CHECKING
26from typing import TypeVar
27from typing import Union
29from . import exc
30from ._typing import insp_is_mapper
31from .. import exc as sa_exc
32from .. import inspection
33from .. import util
34from ..sql import roles
35from ..sql.elements import SQLColumnExpression
36from ..sql.elements import SQLCoreOperations
37from ..util import FastIntFlag
38from ..util.langhelpers import TypingOnly
40if typing.TYPE_CHECKING:
41 from ._typing import _EntityType
42 from ._typing import _ExternalEntityType
43 from ._typing import _InternalEntityType
44 from .attributes import InstrumentedAttribute
45 from .dynamic import AppenderQuery
46 from .instrumentation import ClassManager
47 from .interfaces import PropComparator
48 from .mapper import Mapper
49 from .state import InstanceState
50 from .util import AliasedClass
51 from .writeonly import WriteOnlyCollection
52 from ..sql._typing import _ColumnExpressionArgument
53 from ..sql._typing import _InfoType
54 from ..sql.elements import ColumnElement
55 from ..sql.operators import OperatorType
57_T = TypeVar("_T", bound=Any)
58_T_co = TypeVar("_T_co", bound=Any, covariant=True)
60_O = TypeVar("_O", bound=object)
63class LoaderCallableStatus(Enum):
64 PASSIVE_NO_RESULT = 0
65 """Symbol returned by a loader callable or other attribute/history
66 retrieval operation when a value could not be determined, based
67 on loader callable flags.
68 """
70 PASSIVE_CLASS_MISMATCH = 1
71 """Symbol indicating that an object is locally present for a given
72 primary key identity but it is not of the requested class. The
73 return value is therefore None and no SQL should be emitted."""
75 ATTR_WAS_SET = 2
76 """Symbol returned by a loader callable to indicate the
77 retrieved value, or values, were assigned to their attributes
78 on the target object.
79 """
81 ATTR_EMPTY = 3
82 """Symbol used internally to indicate an attribute had no callable."""
84 NO_VALUE = 4
85 """Symbol which may be placed as the 'previous' value of an attribute,
86 indicating no value was loaded for an attribute when it was modified,
87 and flags indicated we were not to load it.
88 """
90 NEVER_SET = NO_VALUE
91 """
92 Synonymous with NO_VALUE
94 .. versionchanged:: 1.4 NEVER_SET was merged with NO_VALUE
96 """
98 DONT_SET = 5
101(
102 PASSIVE_NO_RESULT,
103 PASSIVE_CLASS_MISMATCH,
104 ATTR_WAS_SET,
105 ATTR_EMPTY,
106 NO_VALUE,
107 DONT_SET,
108) = tuple(LoaderCallableStatus)
110NEVER_SET = NO_VALUE
113class PassiveFlag(FastIntFlag):
114 """Bitflag interface that passes options onto loader callables"""
116 NO_CHANGE = 0
117 """No callables or SQL should be emitted on attribute access
118 and no state should change
119 """
121 CALLABLES_OK = 1
122 """Loader callables can be fired off if a value
123 is not present.
124 """
126 SQL_OK = 2
127 """Loader callables can emit SQL at least on scalar value attributes."""
129 RELATED_OBJECT_OK = 4
130 """Callables can use SQL to load related objects as well
131 as scalar value attributes.
132 """
134 INIT_OK = 8
135 """Attributes should be initialized with a blank
136 value (None or an empty collection) upon get, if no other
137 value can be obtained.
138 """
140 NON_PERSISTENT_OK = 16
141 """Callables can be emitted if the parent is not persistent."""
143 LOAD_AGAINST_COMMITTED = 32
144 """Callables should use committed values as primary/foreign keys during a
145 load.
146 """
148 NO_AUTOFLUSH = 64
149 """Loader callables should disable autoflush."""
151 NO_RAISE = 128
152 """Loader callables should not raise any assertions"""
154 DEFERRED_HISTORY_LOAD = 256
155 """indicates special load of the previous value of an attribute"""
157 INCLUDE_PENDING_MUTATIONS = 512
159 # pre-packaged sets of flags used as inputs
160 PASSIVE_OFF = (
161 RELATED_OBJECT_OK | NON_PERSISTENT_OK | INIT_OK | CALLABLES_OK | SQL_OK
162 )
163 "Callables can be emitted in all cases."
165 PASSIVE_RETURN_NO_VALUE = PASSIVE_OFF ^ INIT_OK
166 """PASSIVE_OFF ^ INIT_OK"""
168 PASSIVE_NO_INITIALIZE = PASSIVE_RETURN_NO_VALUE ^ CALLABLES_OK
169 "PASSIVE_RETURN_NO_VALUE ^ CALLABLES_OK"
171 PASSIVE_NO_FETCH = PASSIVE_OFF ^ SQL_OK
172 "PASSIVE_OFF ^ SQL_OK"
174 PASSIVE_NO_FETCH_RELATED = PASSIVE_OFF ^ RELATED_OBJECT_OK
175 "PASSIVE_OFF ^ RELATED_OBJECT_OK"
177 PASSIVE_ONLY_PERSISTENT = PASSIVE_OFF ^ NON_PERSISTENT_OK
178 "PASSIVE_OFF ^ NON_PERSISTENT_OK"
180 PASSIVE_MERGE = PASSIVE_OFF | NO_RAISE
181 """PASSIVE_OFF | NO_RAISE
183 Symbol used specifically for session.merge() and similar cases
185 """
188(
189 NO_CHANGE,
190 CALLABLES_OK,
191 SQL_OK,
192 RELATED_OBJECT_OK,
193 INIT_OK,
194 NON_PERSISTENT_OK,
195 LOAD_AGAINST_COMMITTED,
196 NO_AUTOFLUSH,
197 NO_RAISE,
198 DEFERRED_HISTORY_LOAD,
199 INCLUDE_PENDING_MUTATIONS,
200 PASSIVE_OFF,
201 PASSIVE_RETURN_NO_VALUE,
202 PASSIVE_NO_INITIALIZE,
203 PASSIVE_NO_FETCH,
204 PASSIVE_NO_FETCH_RELATED,
205 PASSIVE_ONLY_PERSISTENT,
206 PASSIVE_MERGE,
207) = PassiveFlag.__members__.values()
209DEFAULT_MANAGER_ATTR = "_sa_class_manager"
210DEFAULT_STATE_ATTR = "_sa_instance_state"
213class EventConstants(Enum):
214 EXT_CONTINUE = 1
215 EXT_STOP = 2
216 EXT_SKIP = 3
217 NO_KEY = 4
218 """indicates an :class:`.AttributeEvent` event that did not have any
219 key argument.
221 .. versionadded:: 2.0
223 """
226EXT_CONTINUE, EXT_STOP, EXT_SKIP, NO_KEY = tuple(EventConstants)
229class RelationshipDirection(Enum):
230 """enumeration which indicates the 'direction' of a
231 :class:`_orm.RelationshipProperty`.
233 :class:`.RelationshipDirection` is accessible from the
234 :attr:`_orm.Relationship.direction` attribute of
235 :class:`_orm.RelationshipProperty`.
237 """
239 ONETOMANY = 1
240 """Indicates the one-to-many direction for a :func:`_orm.relationship`.
242 This symbol is typically used by the internals but may be exposed within
243 certain API features.
245 """
247 MANYTOONE = 2
248 """Indicates the many-to-one direction for a :func:`_orm.relationship`.
250 This symbol is typically used by the internals but may be exposed within
251 certain API features.
253 """
255 MANYTOMANY = 3
256 """Indicates the many-to-many direction for a :func:`_orm.relationship`.
258 This symbol is typically used by the internals but may be exposed within
259 certain API features.
261 """
264ONETOMANY, MANYTOONE, MANYTOMANY = tuple(RelationshipDirection)
267class InspectionAttrExtensionType(Enum):
268 """Symbols indicating the type of extension that a
269 :class:`.InspectionAttr` is part of."""
272class NotExtension(InspectionAttrExtensionType):
273 NOT_EXTENSION = "not_extension"
274 """Symbol indicating an :class:`InspectionAttr` that's
275 not part of sqlalchemy.ext.
277 Is assigned to the :attr:`.InspectionAttr.extension_type`
278 attribute.
280 """
283_never_set = frozenset([NEVER_SET])
285_none_set = frozenset([None, NEVER_SET, PASSIVE_NO_RESULT])
287_none_only_set = frozenset([None])
289_SET_DEFERRED_EXPIRED = util.symbol("SET_DEFERRED_EXPIRED")
291_DEFER_FOR_STATE = util.symbol("DEFER_FOR_STATE")
293_RAISE_FOR_STATE = util.symbol("RAISE_FOR_STATE")
296_F = TypeVar("_F", bound=Callable[..., Any])
297_Self = TypeVar("_Self")
300def _assertions(
301 *assertions: Any,
302) -> Callable[[_F], _F]:
303 @util.decorator
304 def generate(fn: _F, self: _Self, *args: Any, **kw: Any) -> _Self:
305 for assertion in assertions:
306 assertion(self, fn.__name__)
307 fn(self, *args, **kw)
308 return self
310 return generate
313if TYPE_CHECKING:
315 def manager_of_class(cls: Type[_O]) -> ClassManager[_O]: ...
317 @overload
318 def opt_manager_of_class(cls: AliasedClass[Any]) -> None: ...
320 @overload
321 def opt_manager_of_class(
322 cls: _ExternalEntityType[_O],
323 ) -> Optional[ClassManager[_O]]: ...
325 def opt_manager_of_class(
326 cls: _ExternalEntityType[_O],
327 ) -> Optional[ClassManager[_O]]: ...
329 def instance_state(instance: _O) -> InstanceState[_O]: ...
331 def instance_dict(instance: object) -> Dict[str, Any]: ...
333else:
334 # these can be replaced by sqlalchemy.ext.instrumentation
335 # if augmented class instrumentation is enabled.
337 def manager_of_class(cls):
338 try:
339 return cls.__dict__[DEFAULT_MANAGER_ATTR]
340 except KeyError as ke:
341 raise exc.UnmappedClassError(
342 cls, f"Can't locate an instrumentation manager for class {cls}"
343 ) from ke
345 def opt_manager_of_class(cls):
346 return cls.__dict__.get(DEFAULT_MANAGER_ATTR)
348 instance_state = operator.attrgetter(DEFAULT_STATE_ATTR)
350 instance_dict = operator.attrgetter("__dict__")
353def instance_str(instance: object) -> str:
354 """Return a string describing an instance."""
356 return state_str(instance_state(instance))
359def state_str(state: InstanceState[Any]) -> str:
360 """Return a string describing an instance via its InstanceState."""
362 if state is None:
363 return "None"
364 else:
365 return "<%s at 0x%x>" % (state.class_.__name__, id(state.obj()))
368def state_class_str(state: InstanceState[Any]) -> str:
369 """Return a string describing an instance's class via its
370 InstanceState.
371 """
373 if state is None:
374 return "None"
375 else:
376 return "<%s>" % (state.class_.__name__,)
379def attribute_str(instance: object, attribute: str) -> str:
380 return instance_str(instance) + "." + attribute
383def state_attribute_str(state: InstanceState[Any], attribute: str) -> str:
384 return state_str(state) + "." + attribute
387def object_mapper(instance: _T) -> Mapper[_T]:
388 """Given an object, return the primary Mapper associated with the object
389 instance.
391 Raises :class:`sqlalchemy.orm.exc.UnmappedInstanceError`
392 if no mapping is configured.
394 This function is available via the inspection system as::
396 inspect(instance).mapper
398 Using the inspection system will raise
399 :class:`sqlalchemy.exc.NoInspectionAvailable` if the instance is
400 not part of a mapping.
402 """
403 return object_state(instance).mapper
406def object_state(instance: _T) -> InstanceState[_T]:
407 """Given an object, return the :class:`.InstanceState`
408 associated with the object.
410 Raises :class:`sqlalchemy.orm.exc.UnmappedInstanceError`
411 if no mapping is configured.
413 Equivalent functionality is available via the :func:`_sa.inspect`
414 function as::
416 inspect(instance)
418 Using the inspection system will raise
419 :class:`sqlalchemy.exc.NoInspectionAvailable` if the instance is
420 not part of a mapping.
422 """
423 state = _inspect_mapped_object(instance)
424 if state is None:
425 raise exc.UnmappedInstanceError(instance)
426 else:
427 return state
430@inspection._inspects(object)
431def _inspect_mapped_object(instance: _T) -> Optional[InstanceState[_T]]:
432 try:
433 return instance_state(instance)
434 except (exc.UnmappedClassError,) + exc.NO_STATE:
435 return None
438def _class_to_mapper(
439 class_or_mapper: Union[Mapper[_T], Type[_T]],
440) -> Mapper[_T]:
441 # can't get mypy to see an overload for this
442 insp = inspection.inspect(class_or_mapper, False)
443 if insp is not None:
444 return insp.mapper # type: ignore
445 else:
446 assert isinstance(class_or_mapper, type)
447 raise exc.UnmappedClassError(class_or_mapper)
450def _mapper_or_none(
451 entity: Union[Type[_T], _InternalEntityType[_T]],
452) -> Optional[Mapper[_T]]:
453 """Return the :class:`_orm.Mapper` for the given class or None if the
454 class is not mapped.
455 """
457 # can't get mypy to see an overload for this
458 insp = inspection.inspect(entity, False)
459 if insp is not None:
460 return insp.mapper # type: ignore
461 else:
462 return None
465def _is_mapped_class(entity: Any) -> bool:
466 """Return True if the given object is a mapped class,
467 :class:`_orm.Mapper`, or :class:`.AliasedClass`.
468 """
470 insp = inspection.inspect(entity, False)
471 return (
472 insp is not None
473 and not insp.is_clause_element
474 and (insp.is_mapper or insp.is_aliased_class)
475 )
478def _is_aliased_class(entity: Any) -> bool:
479 insp = inspection.inspect(entity, False)
480 return insp is not None and getattr(insp, "is_aliased_class", False)
483@no_type_check
484def _entity_descriptor(entity: _EntityType[Any], key: str) -> Any:
485 """Return a class attribute given an entity and string name.
487 May return :class:`.InstrumentedAttribute` or user-defined
488 attribute.
490 """
491 insp = inspection.inspect(entity)
492 if insp.is_selectable:
493 description = entity
494 entity = insp.c
495 elif insp.is_aliased_class:
496 entity = insp.entity
497 description = entity
498 elif hasattr(insp, "mapper"):
499 description = entity = insp.mapper.class_
500 else:
501 description = entity
503 try:
504 return getattr(entity, key)
505 except AttributeError as err:
506 raise sa_exc.InvalidRequestError(
507 "Entity '%s' has no property '%s'" % (description, key)
508 ) from err
511if TYPE_CHECKING:
513 def _state_mapper(state: InstanceState[_O]) -> Mapper[_O]: ...
515else:
516 _state_mapper = util.dottedgetter("manager.mapper")
519def _inspect_mapped_class(
520 class_: Type[_O], configure: bool = False
521) -> Optional[Mapper[_O]]:
522 try:
523 class_manager = opt_manager_of_class(class_)
524 if class_manager is None or not class_manager.is_mapped:
525 return None
526 mapper = class_manager.mapper
527 except exc.NO_STATE:
528 return None
529 else:
530 if configure:
531 mapper._check_configure()
532 return mapper
535def _parse_mapper_argument(arg: Union[Mapper[_O], Type[_O]]) -> Mapper[_O]:
536 insp = inspection.inspect(arg, raiseerr=False)
537 if insp_is_mapper(insp):
538 return insp
540 raise sa_exc.ArgumentError(f"Mapper or mapped class expected, got {arg!r}")
543def class_mapper(class_: Type[_O], configure: bool = True) -> Mapper[_O]:
544 """Given a class, return the primary :class:`_orm.Mapper` associated
545 with the key.
547 Raises :exc:`.UnmappedClassError` if no mapping is configured
548 on the given class, or :exc:`.ArgumentError` if a non-class
549 object is passed.
551 Equivalent functionality is available via the :func:`_sa.inspect`
552 function as::
554 inspect(some_mapped_class)
556 Using the inspection system will raise
557 :class:`sqlalchemy.exc.NoInspectionAvailable` if the class is not mapped.
559 """
560 mapper = _inspect_mapped_class(class_, configure=configure)
561 if mapper is None:
562 if not isinstance(class_, type):
563 raise sa_exc.ArgumentError(
564 "Class object expected, got '%r'." % (class_,)
565 )
566 raise exc.UnmappedClassError(class_)
567 else:
568 return mapper
571class InspectionAttr:
572 """A base class applied to all ORM objects and attributes that are
573 related to things that can be returned by the :func:`_sa.inspect` function.
575 The attributes defined here allow the usage of simple boolean
576 checks to test basic facts about the object returned.
578 While the boolean checks here are basically the same as using
579 the Python isinstance() function, the flags here can be used without
580 the need to import all of these classes, and also such that
581 the SQLAlchemy class system can change while leaving the flags
582 here intact for forwards-compatibility.
584 """
586 __slots__: Tuple[str, ...] = ()
588 is_selectable = False
589 """Return True if this object is an instance of
590 :class:`_expression.Selectable`."""
592 is_aliased_class = False
593 """True if this object is an instance of :class:`.AliasedClass`."""
595 is_instance = False
596 """True if this object is an instance of :class:`.InstanceState`."""
598 is_mapper = False
599 """True if this object is an instance of :class:`_orm.Mapper`."""
601 is_bundle = False
602 """True if this object is an instance of :class:`.Bundle`."""
604 is_property = False
605 """True if this object is an instance of :class:`.MapperProperty`."""
607 is_attribute = False
608 """True if this object is a Python :term:`descriptor`.
610 This can refer to one of many types. Usually a
611 :class:`.QueryableAttribute` which handles attributes events on behalf
612 of a :class:`.MapperProperty`. But can also be an extension type
613 such as :class:`.AssociationProxy` or :class:`.hybrid_property`.
614 The :attr:`.InspectionAttr.extension_type` will refer to a constant
615 identifying the specific subtype.
617 .. seealso::
619 :attr:`_orm.Mapper.all_orm_descriptors`
621 """
623 _is_internal_proxy = False
624 """True if this object is an internal proxy object."""
626 is_clause_element = False
627 """True if this object is an instance of
628 :class:`_expression.ClauseElement`."""
630 extension_type: InspectionAttrExtensionType = NotExtension.NOT_EXTENSION
631 """The extension type, if any.
632 Defaults to :attr:`.interfaces.NotExtension.NOT_EXTENSION`
634 .. seealso::
636 :class:`.HybridExtensionType`
638 :class:`.AssociationProxyExtensionType`
640 """
643class InspectionAttrInfo(InspectionAttr):
644 """Adds the ``.info`` attribute to :class:`.InspectionAttr`.
646 The rationale for :class:`.InspectionAttr` vs. :class:`.InspectionAttrInfo`
647 is that the former is compatible as a mixin for classes that specify
648 ``__slots__``; this is essentially an implementation artifact.
650 """
652 __slots__ = ()
654 @util.ro_memoized_property
655 def info(self) -> _InfoType:
656 """Info dictionary associated with the object, allowing user-defined
657 data to be associated with this :class:`.InspectionAttr`.
659 The dictionary is generated when first accessed. Alternatively,
660 it can be specified as a constructor argument to the
661 :func:`.column_property`, :func:`_orm.relationship`, or
662 :func:`.composite`
663 functions.
665 .. seealso::
667 :attr:`.QueryableAttribute.info`
669 :attr:`.SchemaItem.info`
671 """
672 return {}
675class SQLORMOperations(SQLCoreOperations[_T_co], TypingOnly):
676 __slots__ = ()
678 if typing.TYPE_CHECKING:
680 def of_type(
681 self, class_: _EntityType[Any]
682 ) -> PropComparator[_T_co]: ...
684 def and_(
685 self, *criteria: _ColumnExpressionArgument[bool]
686 ) -> PropComparator[bool]: ...
688 def any( # noqa: A001
689 self,
690 criterion: Optional[_ColumnExpressionArgument[bool]] = None,
691 **kwargs: Any,
692 ) -> ColumnElement[bool]: ...
694 def has(
695 self,
696 criterion: Optional[_ColumnExpressionArgument[bool]] = None,
697 **kwargs: Any,
698 ) -> ColumnElement[bool]: ...
701class ORMDescriptor(Generic[_T_co], TypingOnly):
702 """Represent any Python descriptor that provides a SQL expression
703 construct at the class level."""
705 __slots__ = ()
707 if typing.TYPE_CHECKING:
709 @overload
710 def __get__(
711 self, instance: Any, owner: Literal[None]
712 ) -> ORMDescriptor[_T_co]: ...
714 @overload
715 def __get__(
716 self, instance: Literal[None], owner: Any
717 ) -> SQLCoreOperations[_T_co]: ...
719 @overload
720 def __get__(self, instance: object, owner: Any) -> _T_co: ...
722 def __get__(
723 self, instance: object, owner: Any
724 ) -> Union[ORMDescriptor[_T_co], SQLCoreOperations[_T_co], _T_co]: ...
727class _MappedAnnotationBase(Generic[_T_co], TypingOnly):
728 """common class for Mapped and similar ORM container classes.
730 these are classes that can appear on the left side of an ORM declarative
731 mapping, containing a mapped class or in some cases a collection
732 surrounding a mapped class.
734 """
736 __slots__ = ()
739class SQLORMExpression(
740 SQLORMOperations[_T_co], SQLColumnExpression[_T_co], TypingOnly
741):
742 """A type that may be used to indicate any ORM-level attribute or
743 object that acts in place of one, in the context of SQL expression
744 construction.
746 :class:`.SQLORMExpression` extends from the Core
747 :class:`.SQLColumnExpression` to add additional SQL methods that are ORM
748 specific, such as :meth:`.PropComparator.of_type`, and is part of the bases
749 for :class:`.InstrumentedAttribute`. It may be used in :pep:`484` typing to
750 indicate arguments or return values that should behave as ORM-level
751 attribute expressions.
753 .. versionadded:: 2.0.0b4
756 """
758 __slots__ = ()
761class Mapped(
762 SQLORMExpression[_T_co],
763 ORMDescriptor[_T_co],
764 _MappedAnnotationBase[_T_co],
765 roles.DDLConstraintColumnRole,
766):
767 """Represent an ORM mapped attribute on a mapped class.
769 This class represents the complete descriptor interface for any class
770 attribute that will have been :term:`instrumented` by the ORM
771 :class:`_orm.Mapper` class. Provides appropriate information to type
772 checkers such as pylance and mypy so that ORM-mapped attributes
773 are correctly typed.
775 The most prominent use of :class:`_orm.Mapped` is in
776 the :ref:`Declarative Mapping <orm_explicit_declarative_base>` form
777 of :class:`_orm.Mapper` configuration, where used explicitly it drives
778 the configuration of ORM attributes such as :func:`_orm.mapped_class`
779 and :func:`_orm.relationship`.
781 .. seealso::
783 :ref:`orm_explicit_declarative_base`
785 :ref:`orm_declarative_table`
787 .. tip::
789 The :class:`_orm.Mapped` class represents attributes that are handled
790 directly by the :class:`_orm.Mapper` class. It does not include other
791 Python descriptor classes that are provided as extensions, including
792 :ref:`hybrids_toplevel` and the :ref:`associationproxy_toplevel`.
793 While these systems still make use of ORM-specific superclasses
794 and structures, they are not :term:`instrumented` by the
795 :class:`_orm.Mapper` and instead provide their own functionality
796 when they are accessed on a class.
798 .. versionadded:: 1.4
801 """
803 __slots__ = ()
805 if typing.TYPE_CHECKING:
807 @overload
808 def __get__(
809 self, instance: None, owner: Any
810 ) -> InstrumentedAttribute[_T_co]: ...
812 @overload
813 def __get__(self, instance: object, owner: Any) -> _T_co: ...
815 def __get__(
816 self, instance: Optional[object], owner: Any
817 ) -> Union[InstrumentedAttribute[_T_co], _T_co]: ...
819 @classmethod
820 def _empty_constructor(cls, arg1: Any) -> Mapped[_T_co]: ...
822 def __set__(
823 self, instance: Any, value: Union[SQLCoreOperations[_T_co], _T_co]
824 ) -> None: ...
826 def __delete__(self, instance: Any) -> None: ...
829class _MappedAttribute(Generic[_T_co], TypingOnly):
830 """Mixin for attributes which should be replaced by mapper-assigned
831 attributes.
833 """
835 __slots__ = ()
838class _DeclarativeMapped(Mapped[_T_co], _MappedAttribute[_T_co]):
839 """Mixin for :class:`.MapperProperty` subclasses that allows them to
840 be compatible with ORM-annotated declarative mappings.
842 """
844 __slots__ = ()
846 # MappedSQLExpression, Relationship, Composite etc. dont actually do
847 # SQL expression behavior. yet there is code that compares them with
848 # __eq__(), __ne__(), etc. Since #8847 made Mapped even more full
849 # featured including ColumnOperators, we need to have those methods
850 # be no-ops for these objects, so return NotImplemented to fall back
851 # to normal comparison behavior.
852 def operate(self, op: OperatorType, *other: Any, **kwargs: Any) -> Any:
853 return NotImplemented
855 __sa_operate__ = operate
857 def reverse_operate(
858 self, op: OperatorType, other: Any, **kwargs: Any
859 ) -> Any:
860 return NotImplemented
863class DynamicMapped(_MappedAnnotationBase[_T_co]):
864 """Represent the ORM mapped attribute type for a "dynamic" relationship.
866 The :class:`_orm.DynamicMapped` type annotation may be used in an
867 :ref:`Annotated Declarative Table <orm_declarative_mapped_column>` mapping
868 to indicate that the ``lazy="dynamic"`` loader strategy should be used
869 for a particular :func:`_orm.relationship`.
871 .. legacy:: The "dynamic" lazy loader strategy is the legacy form of what
872 is now the "write_only" strategy described in the section
873 :ref:`write_only_relationship`.
875 E.g.::
877 class User(Base):
878 __tablename__ = "user"
879 id: Mapped[int] = mapped_column(primary_key=True)
880 addresses: DynamicMapped[Address] = relationship(
881 cascade="all,delete-orphan"
882 )
884 See the section :ref:`dynamic_relationship` for background.
886 .. versionadded:: 2.0
888 .. seealso::
890 :ref:`dynamic_relationship` - complete background
892 :class:`.WriteOnlyMapped` - fully 2.0 style version
894 """
896 __slots__ = ()
898 if TYPE_CHECKING:
900 @overload
901 def __get__(
902 self, instance: None, owner: Any
903 ) -> InstrumentedAttribute[_T_co]: ...
905 @overload
906 def __get__(
907 self, instance: object, owner: Any
908 ) -> AppenderQuery[_T_co]: ...
910 def __get__(
911 self, instance: Optional[object], owner: Any
912 ) -> Union[InstrumentedAttribute[_T_co], AppenderQuery[_T_co]]: ...
914 def __set__(
915 self, instance: Any, value: typing.Collection[_T_co]
916 ) -> None: ...
919class WriteOnlyMapped(_MappedAnnotationBase[_T_co]):
920 """Represent the ORM mapped attribute type for a "write only" relationship.
922 The :class:`_orm.WriteOnlyMapped` type annotation may be used in an
923 :ref:`Annotated Declarative Table <orm_declarative_mapped_column>` mapping
924 to indicate that the ``lazy="write_only"`` loader strategy should be used
925 for a particular :func:`_orm.relationship`.
927 E.g.::
929 class User(Base):
930 __tablename__ = "user"
931 id: Mapped[int] = mapped_column(primary_key=True)
932 addresses: WriteOnlyMapped[Address] = relationship(
933 cascade="all,delete-orphan"
934 )
936 See the section :ref:`write_only_relationship` for background.
938 .. versionadded:: 2.0
940 .. seealso::
942 :ref:`write_only_relationship` - complete background
944 :class:`.DynamicMapped` - includes legacy :class:`_orm.Query` support
946 """
948 __slots__ = ()
950 if TYPE_CHECKING:
952 @overload
953 def __get__(
954 self, instance: None, owner: Any
955 ) -> InstrumentedAttribute[_T_co]: ...
957 @overload
958 def __get__(
959 self, instance: object, owner: Any
960 ) -> WriteOnlyCollection[_T_co]: ...
962 def __get__(
963 self, instance: Optional[object], owner: Any
964 ) -> Union[
965 InstrumentedAttribute[_T_co], WriteOnlyCollection[_T_co]
966 ]: ...
968 def __set__(
969 self, instance: Any, value: typing.Collection[_T_co]
970 ) -> None: ...