# orm/interfaces.py # Copyright (C) 2005-2022 the SQLAlchemy authors and contributors # # # This module is part of SQLAlchemy and is released under # the MIT License: https://www.opensource.org/licenses/mit-license.php """ Contains various base classes used throughout the ORM. Defines some key base classes prominent within the internals. This module and the classes within are mostly private, though some attributes are exposed when inspecting mappings. """ from __future__ import annotations import collections import dataclasses import typing from typing import Any from typing import Callable from typing import cast from typing import ClassVar from typing import Dict from typing import Iterator from typing import List from typing import NamedTuple from typing import NoReturn from typing import Optional from typing import Sequence from typing import Set from typing import Tuple from typing import Type from typing import TYPE_CHECKING from typing import TypeVar from typing import Union from . import exc as orm_exc from . import path_registry from .base import _MappedAttribute as _MappedAttribute from .base import EXT_CONTINUE as EXT_CONTINUE # noqa: F401 from .base import EXT_SKIP as EXT_SKIP # noqa: F401 from .base import EXT_STOP as EXT_STOP # noqa: F401 from .base import InspectionAttr as InspectionAttr # noqa: F401 from .base import InspectionAttrInfo as InspectionAttrInfo from .base import MANYTOMANY as MANYTOMANY # noqa: F401 from .base import MANYTOONE as MANYTOONE # noqa: F401 from .base import NO_KEY as NO_KEY # noqa: F401 from .base import NO_VALUE as NO_VALUE # noqa: F401 from .base import NotExtension as NotExtension # noqa: F401 from .base import ONETOMANY as ONETOMANY # noqa: F401 from .base import RelationshipDirection as RelationshipDirection # noqa: F401 from .base import SQLORMOperations from .. import ColumnElement from .. import exc as sa_exc from .. import inspection from .. import util from ..sql import operators from ..sql import roles from ..sql import visitors from ..sql.base import _NoArg from ..sql.base import ExecutableOption from ..sql.cache_key import HasCacheKey from ..sql.schema import Column from ..sql.type_api import TypeEngine from ..util.typing import RODescriptorReference from ..util.typing import TypedDict if typing.TYPE_CHECKING: from ._typing import _EntityType from ._typing import _IdentityKeyType from ._typing import _InstanceDict from ._typing import _InternalEntityType from ._typing import _ORMAdapterProto from .attributes import InstrumentedAttribute from .context import _MapperEntity from .context import ORMCompileState from .decl_api import RegistryType from .loading import _PopulatorDict from .mapper import Mapper from .path_registry import AbstractEntityRegistry from .query import Query from .session import Session from .state import InstanceState from .strategy_options import _LoadElement from .util import AliasedInsp from .util import ORMAdapter from ..engine.result import Result from ..sql._typing import _ColumnExpressionArgument from ..sql._typing import _ColumnsClauseArgument from ..sql._typing import _DMLColumnArgument from ..sql._typing import _InfoType from ..sql.operators import OperatorType from ..sql.visitors import _TraverseInternalsType from ..util.typing import _AnnotationScanType _StrategyKey = Tuple[Any, ...] _T = TypeVar("_T", bound=Any) _TLS = TypeVar("_TLS", bound="Type[LoaderStrategy]") class ORMStatementRole(roles.StatementRole): __slots__ = () _role_name = ( "Executable SQL or text() construct, including ORM " "aware objects" ) class ORMColumnsClauseRole( roles.ColumnsClauseRole, roles.TypedColumnsClauseRole[_T] ): __slots__ = () _role_name = "ORM mapped entity, aliased entity, or Column expression" class ORMEntityColumnsClauseRole(ORMColumnsClauseRole[_T]): __slots__ = () _role_name = "ORM mapped or aliased entity" class ORMFromClauseRole(roles.StrictFromClauseRole): __slots__ = () _role_name = "ORM mapped entity, aliased entity, or FROM expression" class ORMColumnDescription(TypedDict): name: str # TODO: add python_type and sql_type here; combining them # into "type" is a bad idea type: Union[Type[Any], TypeEngine[Any]] aliased: bool expr: _ColumnsClauseArgument[Any] entity: Optional[_ColumnsClauseArgument[Any]] class _IntrospectsAnnotations: __slots__ = () def found_in_pep593_annotated(self) -> Any: """return a copy of this object to use in declarative when the object is found inside of an Annotated object.""" raise NotImplementedError( f"Use of the {self.__class__} construct inside of an " f"Annotated object is not yet supported." ) def declarative_scan( self, registry: RegistryType, cls: Type[Any], key: str, annotation: Optional[_AnnotationScanType], extracted_mapped_annotation: Optional[_AnnotationScanType], is_dataclass_field: bool, ) -> None: """Perform class-specific initializaton at early declarative scanning time. .. versionadded:: 2.0 """ def _raise_for_required(self, key: str, cls: Type[Any]) -> NoReturn: raise sa_exc.ArgumentError( f"Python typing annotation is required for attribute " f'"{cls.__name__}.{key}" when primary argument(s) for ' f'"{self.__class__.__name__}" construct are None or not present' ) class _AttributeOptions(NamedTuple): """define Python-local attribute behavior options common to all :class:`.MapperProperty` objects. Currently this includes dataclass-generation arguments. .. versionadded:: 2.0 """ dataclasses_init: Union[_NoArg, bool] dataclasses_repr: Union[_NoArg, bool] dataclasses_default: Union[_NoArg, Any] dataclasses_default_factory: Union[_NoArg, Callable[[], Any]] dataclasses_kw_only: Union[_NoArg, bool] def _as_dataclass_field(self) -> Any: """Return a ``dataclasses.Field`` object given these arguments.""" kw: Dict[str, Any] = {} if self.dataclasses_default_factory is not _NoArg.NO_ARG: kw["default_factory"] = self.dataclasses_default_factory if self.dataclasses_default is not _NoArg.NO_ARG: kw["default"] = self.dataclasses_default if self.dataclasses_init is not _NoArg.NO_ARG: kw["init"] = self.dataclasses_init if self.dataclasses_repr is not _NoArg.NO_ARG: kw["repr"] = self.dataclasses_repr if self.dataclasses_kw_only is not _NoArg.NO_ARG: kw["kw_only"] = self.dataclasses_kw_only return dataclasses.field(**kw) @classmethod def _get_arguments_for_make_dataclass( cls, key: str, annotation: Type[Any], elem: _T ) -> Union[ Tuple[str, Type[Any]], Tuple[str, Type[Any], dataclasses.Field[Any]] ]: """given attribute key, annotation, and value from a class, return the argument tuple we would pass to dataclasses.make_dataclass() for this attribute. """ if isinstance(elem, (MapperProperty, _MapsColumns)): dc_field = elem._attribute_options._as_dataclass_field() return (key, annotation, dc_field) elif elem is not _NoArg.NO_ARG: # why is typing not erroring on this? return (key, annotation, elem) else: return (key, annotation) _DEFAULT_ATTRIBUTE_OPTIONS = _AttributeOptions( _NoArg.NO_ARG, _NoArg.NO_ARG, _NoArg.NO_ARG, _NoArg.NO_ARG, _NoArg.NO_ARG ) class _MapsColumns(_MappedAttribute[_T]): """interface for declarative-capable construct that delivers one or more Column objects to the declarative process to be part of a Table. """ __slots__ = () _attribute_options: _AttributeOptions _has_dataclass_arguments: bool @property def mapper_property_to_assign(self) -> Optional[MapperProperty[_T]]: """return a MapperProperty to be assigned to the declarative mapping""" raise NotImplementedError() @property def columns_to_assign(self) -> List[Column[_T]]: """A list of Column objects that should be declaratively added to the new Table object. """ raise NotImplementedError() # NOTE: MapperProperty needs to extend _MappedAttribute so that declarative # typing works, i.e. "Mapped[A] = relationship()". This introduces an # inconvenience which is that all the MapperProperty objects are treated # as descriptors by typing tools, which are misled by this as assignment / # access to a descriptor attribute wants to move through __get__. # Therefore, references to MapperProperty as an instance variable, such # as in PropComparator, may have some special typing workarounds such as the # use of sqlalchemy.util.typing.DescriptorReference to avoid mis-interpretation # by typing tools @inspection._self_inspects class MapperProperty( HasCacheKey, _MappedAttribute[_T], InspectionAttrInfo, util.MemoizedSlots ): """Represent a particular class attribute mapped by :class:`_orm.Mapper`. The most common occurrences of :class:`.MapperProperty` are the mapped :class:`_schema.Column`, which is represented in a mapping as an instance of :class:`.ColumnProperty`, and a reference to another class produced by :func:`_orm.relationship`, represented in the mapping as an instance of :class:`.Relationship`. """ __slots__ = ( "_configure_started", "_configure_finished", "_attribute_options", "_has_dataclass_arguments", "parent", "key", "info", "doc", ) _cache_key_traversal: _TraverseInternalsType = [ ("parent", visitors.ExtendedInternalTraversal.dp_has_cache_key), ("key", visitors.ExtendedInternalTraversal.dp_string), ] if not TYPE_CHECKING: cascade = None is_property = True """Part of the InspectionAttr interface; states this object is a mapper property. """ comparator: PropComparator[_T] """The :class:`_orm.PropComparator` instance that implements SQL expression construction on behalf of this mapped attribute.""" key: str """name of class attribute""" parent: Mapper[Any] """the :class:`.Mapper` managing this property.""" _is_relationship = False _links_to_entity: bool """True if this MapperProperty refers to a mapped entity. Should only be True for Relationship, False for all others. """ doc: Optional[str] """optional documentation string""" _attribute_options: _AttributeOptions """behavioral options for ORM-enabled Python attributes .. versionadded:: 2.0 """ info: _InfoType """Info dictionary associated with the object, allowing user-defined data to be associated with this :class:`.InspectionAttr`. The dictionary is generated when first accessed. Alternatively, it can be specified as a constructor argument to the :func:`.column_property`, :func:`_orm.relationship`, or :func:`.composite` functions. .. versionchanged:: 1.0.0 :attr:`.InspectionAttr.info` moved from :class:`.MapperProperty` so that it can apply to a wider variety of ORM and extension constructs. .. seealso:: :attr:`.QueryableAttribute.info` :attr:`.SchemaItem.info` """ _has_dataclass_arguments: bool def _memoized_attr_info(self) -> _InfoType: """Info dictionary associated with the object, allowing user-defined data to be associated with this :class:`.InspectionAttr`. The dictionary is generated when first accessed. Alternatively, it can be specified as a constructor argument to the :func:`.column_property`, :func:`_orm.relationship`, or :func:`.composite` functions. .. versionchanged:: 1.0.0 :attr:`.MapperProperty.info` is also available on extension types via the :attr:`.InspectionAttrInfo.info` attribute, so that it can apply to a wider variety of ORM and extension constructs. .. seealso:: :attr:`.QueryableAttribute.info` :attr:`.SchemaItem.info` """ return {} def setup( self, context: ORMCompileState, query_entity: _MapperEntity, path: AbstractEntityRegistry, adapter: Optional[ORMAdapter], **kwargs: Any, ) -> None: """Called by Query for the purposes of constructing a SQL statement. Each MapperProperty associated with the target mapper processes the statement referenced by the query context, adding columns and/or criterion as appropriate. """ def create_row_processor( self, context: ORMCompileState, query_entity: _MapperEntity, path: AbstractEntityRegistry, mapper: Mapper[Any], result: Result[Any], adapter: Optional[ORMAdapter], populators: _PopulatorDict, ) -> None: """Produce row processing functions and append to the given set of populators lists. """ def cascade_iterator( self, type_: str, state: InstanceState[Any], dict_: _InstanceDict, visited_states: Set[InstanceState[Any]], halt_on: Optional[Callable[[InstanceState[Any]], bool]] = None, ) -> Iterator[ Tuple[object, Mapper[Any], InstanceState[Any], _InstanceDict] ]: """Iterate through instances related to the given instance for a particular 'cascade', starting with this MapperProperty. Return an iterator3-tuples (instance, mapper, state). Note that the 'cascade' collection on this MapperProperty is checked first for the given type before cascade_iterator is called. This method typically only applies to Relationship. """ return iter(()) def set_parent(self, parent: Mapper[Any], init: bool) -> None: """Set the parent mapper that references this MapperProperty. This method is overridden by some subclasses to perform extra setup when the mapper is first known. """ self.parent = parent def instrument_class(self, mapper: Mapper[Any]) -> None: """Hook called by the Mapper to the property to initiate instrumentation of the class attribute managed by this MapperProperty. The MapperProperty here will typically call out to the attributes module to set up an InstrumentedAttribute. This step is the first of two steps to set up an InstrumentedAttribute, and is called early in the mapper setup process. The second step is typically the init_class_attribute step, called from StrategizedProperty via the post_instrument_class() hook. This step assigns additional state to the InstrumentedAttribute (specifically the "impl") which has been determined after the MapperProperty has determined what kind of persistence management it needs to do (e.g. scalar, object, collection, etc). """ def __init__( self, attribute_options: Optional[_AttributeOptions] = None ) -> None: self._configure_started = False self._configure_finished = False if ( attribute_options and attribute_options != _DEFAULT_ATTRIBUTE_OPTIONS ): self._has_dataclass_arguments = True self._attribute_options = attribute_options else: self._has_dataclass_arguments = False self._attribute_options = _DEFAULT_ATTRIBUTE_OPTIONS def init(self) -> None: """Called after all mappers are created to assemble relationships between mappers and perform other post-mapper-creation initialization steps. """ self._configure_started = True self.do_init() self._configure_finished = True @property def class_attribute(self) -> InstrumentedAttribute[_T]: """Return the class-bound descriptor corresponding to this :class:`.MapperProperty`. This is basically a ``getattr()`` call:: return getattr(self.parent.class_, self.key) I.e. if this :class:`.MapperProperty` were named ``addresses``, and the class to which it is mapped is ``User``, this sequence is possible:: >>> from sqlalchemy import inspect >>> mapper = inspect(User) >>> addresses_property = mapper.attrs.addresses >>> addresses_property.class_attribute is User.addresses True >>> User.addresses.property is addresses_property True """ return getattr(self.parent.class_, self.key) # type: ignore def do_init(self) -> None: """Perform subclass-specific initialization post-mapper-creation steps. This is a template method called by the ``MapperProperty`` object's init() method. """ def post_instrument_class(self, mapper: Mapper[Any]) -> None: """Perform instrumentation adjustments that need to occur after init() has completed. The given Mapper is the Mapper invoking the operation, which may not be the same Mapper as self.parent in an inheritance scenario; however, Mapper will always at least be a sub-mapper of self.parent. This method is typically used by StrategizedProperty, which delegates it to LoaderStrategy.init_class_attribute() to perform final setup on the class-bound InstrumentedAttribute. """ def merge( self, session: Session, source_state: InstanceState[Any], source_dict: _InstanceDict, dest_state: InstanceState[Any], dest_dict: _InstanceDict, load: bool, _recursive: Dict[Any, object], _resolve_conflict_map: Dict[_IdentityKeyType[Any], object], ) -> None: """Merge the attribute represented by this ``MapperProperty`` from source to destination object. """ def __repr__(self) -> str: return "<%s at 0x%x; %s>" % ( self.__class__.__name__, id(self), getattr(self, "key", "no key"), ) @inspection._self_inspects class PropComparator(SQLORMOperations[_T]): r"""Defines SQL operations for ORM mapped attributes. SQLAlchemy allows for operators to be redefined at both the Core and ORM level. :class:`.PropComparator` is the base class of operator redefinition for ORM-level operations, including those of :class:`.ColumnProperty`, :class:`.Relationship`, and :class:`.Composite`. User-defined subclasses of :class:`.PropComparator` may be created. The built-in Python comparison and math operator methods, such as :meth:`.operators.ColumnOperators.__eq__`, :meth:`.operators.ColumnOperators.__lt__`, and :meth:`.operators.ColumnOperators.__add__`, can be overridden to provide new operator behavior. The custom :class:`.PropComparator` is passed to the :class:`.MapperProperty` instance via the ``comparator_factory`` argument. In each case, the appropriate subclass of :class:`.PropComparator` should be used:: # definition of custom PropComparator subclasses from sqlalchemy.orm.properties import \ ColumnProperty,\ Composite,\ Relationship class MyColumnComparator(ColumnProperty.Comparator): def __eq__(self, other): return self.__clause_element__() == other class MyRelationshipComparator(Relationship.Comparator): def any(self, expression): "define the 'any' operation" # ... class MyCompositeComparator(Composite.Comparator): def __gt__(self, other): "redefine the 'greater than' operation" return sql.and_(*[a>b for a, b in zip(self.__clause_element__().clauses, other.__composite_values__())]) # application of custom PropComparator subclasses from sqlalchemy.orm import column_property, relationship, composite from sqlalchemy import Column, String class SomeMappedClass(Base): some_column = column_property(Column("some_column", String), comparator_factory=MyColumnComparator) some_relationship = relationship(SomeOtherClass, comparator_factory=MyRelationshipComparator) some_composite = composite( Column("a", String), Column("b", String), comparator_factory=MyCompositeComparator ) Note that for column-level operator redefinition, it's usually simpler to define the operators at the Core level, using the :attr:`.TypeEngine.comparator_factory` attribute. See :ref:`types_operators` for more detail. .. seealso:: :class:`.ColumnProperty.Comparator` :class:`.Relationship.Comparator` :class:`.Composite.Comparator` :class:`.ColumnOperators` :ref:`types_operators` :attr:`.TypeEngine.comparator_factory` """ __slots__ = "prop", "_parententity", "_adapt_to_entity" __visit_name__ = "orm_prop_comparator" _parententity: _InternalEntityType[Any] _adapt_to_entity: Optional[AliasedInsp[Any]] prop: RODescriptorReference[MapperProperty[_T]] def __init__( self, prop: MapperProperty[_T], parentmapper: _InternalEntityType[Any], adapt_to_entity: Optional[AliasedInsp[Any]] = None, ): self.prop = prop self._parententity = adapt_to_entity or parentmapper self._adapt_to_entity = adapt_to_entity @util.non_memoized_property def property(self) -> MapperProperty[_T]: """Return the :class:`.MapperProperty` associated with this :class:`.PropComparator`. Return values here will commonly be instances of :class:`.ColumnProperty` or :class:`.Relationship`. """ return self.prop def __clause_element__(self) -> roles.ColumnsClauseRole: raise NotImplementedError("%r" % self) def _bulk_update_tuples( self, value: Any ) -> Sequence[Tuple[_DMLColumnArgument, Any]]: """Receive a SQL expression that represents a value in the SET clause of an UPDATE statement. Return a tuple that can be passed to a :class:`_expression.Update` construct. """ return [(cast("_DMLColumnArgument", self.__clause_element__()), value)] def adapt_to_entity( self, adapt_to_entity: AliasedInsp[Any] ) -> PropComparator[_T]: """Return a copy of this PropComparator which will use the given :class:`.AliasedInsp` to produce corresponding expressions. """ return self.__class__(self.prop, self._parententity, adapt_to_entity) @util.ro_non_memoized_property def _parentmapper(self) -> Mapper[Any]: """legacy; this is renamed to _parententity to be compatible with QueryableAttribute.""" return self._parententity.mapper def _criterion_exists( self, criterion: Optional[_ColumnExpressionArgument[bool]] = None, **kwargs: Any, ) -> ColumnElement[Any]: return self.prop.comparator._criterion_exists(criterion, **kwargs) @util.ro_non_memoized_property def adapter(self) -> Optional[_ORMAdapterProto]: """Produce a callable that adapts column expressions to suit an aliased version of this comparator. """ if self._adapt_to_entity is None: return None else: return self._adapt_to_entity._orm_adapt_element @util.ro_non_memoized_property def info(self) -> _InfoType: return self.prop.info @staticmethod def _any_op(a: Any, b: Any, **kwargs: Any) -> Any: return a.any(b, **kwargs) @staticmethod def _has_op(left: Any, other: Any, **kwargs: Any) -> Any: return left.has(other, **kwargs) @staticmethod def _of_type_op(a: Any, class_: Any) -> Any: return a.of_type(class_) any_op = cast(operators.OperatorType, _any_op) has_op = cast(operators.OperatorType, _has_op) of_type_op = cast(operators.OperatorType, _of_type_op) if typing.TYPE_CHECKING: def operate( self, op: OperatorType, *other: Any, **kwargs: Any ) -> ColumnElement[Any]: ... def reverse_operate( self, op: OperatorType, other: Any, **kwargs: Any ) -> ColumnElement[Any]: ... def of_type(self, class_: _EntityType[_T]) -> PropComparator[_T]: r"""Redefine this object in terms of a polymorphic subclass, :func:`_orm.with_polymorphic` construct, or :func:`_orm.aliased` construct. Returns a new PropComparator from which further criterion can be evaluated. e.g.:: query.join(Company.employees.of_type(Engineer)).\ filter(Engineer.name=='foo') :param \class_: a class or mapper indicating that criterion will be against this specific subclass. .. seealso:: :ref:`queryguide_join_onclause` - in the :ref:`queryguide_toplevel` :ref:`inheritance_of_type` """ return self.operate(PropComparator.of_type_op, class_) # type: ignore def and_( self, *criteria: _ColumnExpressionArgument[bool] ) -> PropComparator[bool]: """Add additional criteria to the ON clause that's represented by this relationship attribute. E.g.:: stmt = select(User).join( User.addresses.and_(Address.email_address != 'foo') ) stmt = select(User).options( joinedload(User.addresses.and_(Address.email_address != 'foo')) ) .. versionadded:: 1.4 .. seealso:: :ref:`orm_queryguide_join_on_augmented` :ref:`loader_option_criteria` :func:`.with_loader_criteria` """ return self.operate(operators.and_, *criteria) # type: ignore def any( self, criterion: Optional[_ColumnExpressionArgument[bool]] = None, **kwargs: Any, ) -> ColumnElement[bool]: r"""Return a SQL expression representing true if this element references a member which meets the given criterion. The usual implementation of ``any()`` is :meth:`.Relationship.Comparator.any`. :param criterion: an optional ClauseElement formulated against the member class' table or attributes. :param \**kwargs: key/value pairs corresponding to member class attribute names which will be compared via equality to the corresponding values. """ return self.operate( # type: ignore PropComparator.any_op, criterion, **kwargs ) def has( self, criterion: Optional[_ColumnExpressionArgument[bool]] = None, **kwargs: Any, ) -> ColumnElement[bool]: r"""Return a SQL expression representing true if this element references a member which meets the given criterion. The usual implementation of ``has()`` is :meth:`.Relationship.Comparator.has`. :param criterion: an optional ClauseElement formulated against the member class' table or attributes. :param \**kwargs: key/value pairs corresponding to member class attribute names which will be compared via equality to the corresponding values. """ return self.operate( # type: ignore PropComparator.has_op, criterion, **kwargs ) class StrategizedProperty(MapperProperty[_T]): """A MapperProperty which uses selectable strategies to affect loading behavior. There is a single strategy selected by default. Alternate strategies can be selected at Query time through the usage of ``StrategizedOption`` objects via the Query.options() method. The mechanics of StrategizedProperty are used for every Query invocation for every mapped attribute participating in that Query, to determine first how the attribute will be rendered in SQL and secondly how the attribute will retrieve a value from a result row and apply it to a mapped object. The routines here are very performance-critical. """ __slots__ = ( "_strategies", "strategy", "_wildcard_token", "_default_path_loader_key", "strategy_key", ) inherit_cache = True strategy_wildcard_key: ClassVar[str] strategy_key: _StrategyKey _strategies: Dict[_StrategyKey, LoaderStrategy] def _memoized_attr__wildcard_token(self) -> Tuple[str]: return ( f"{self.strategy_wildcard_key}:{path_registry._WILDCARD_TOKEN}", ) def _memoized_attr__default_path_loader_key( self, ) -> Tuple[str, Tuple[str]]: return ( "loader", (f"{self.strategy_wildcard_key}:{path_registry._DEFAULT_TOKEN}",), ) def _get_context_loader( self, context: ORMCompileState, path: AbstractEntityRegistry ) -> Optional[_LoadElement]: load: Optional[_LoadElement] = None search_path = path[self] # search among: exact match, "attr.*", "default" strategy # if any. for path_key in ( search_path._loader_key, search_path._wildcard_path_loader_key, search_path._default_path_loader_key, ): if path_key in context.attributes: load = context.attributes[path_key] break # note that if strategy_options.Load is placing non-actionable # objects in the context like defaultload(), we would # need to continue the loop here if we got such an # option as below. # if load.strategy or load.local_opts: # break return load def _get_strategy(self, key: _StrategyKey) -> LoaderStrategy: try: return self._strategies[key] except KeyError: pass # run outside to prevent transfer of exception context cls = self._strategy_lookup(self, *key) # this previously was setting self._strategies[cls], that's # a bad idea; should use strategy key at all times because every # strategy has multiple keys at this point self._strategies[key] = strategy = cls(self, key) return strategy def setup( self, context: ORMCompileState, query_entity: _MapperEntity, path: AbstractEntityRegistry, adapter: Optional[ORMAdapter], **kwargs: Any, ) -> None: loader = self._get_context_loader(context, path) if loader and loader.strategy: strat = self._get_strategy(loader.strategy) else: strat = self.strategy strat.setup_query( context, query_entity, path, loader, adapter, **kwargs ) def create_row_processor( self, context: ORMCompileState, query_entity: _MapperEntity, path: AbstractEntityRegistry, mapper: Mapper[Any], result: Result[Any], adapter: Optional[ORMAdapter], populators: _PopulatorDict, ) -> None: loader = self._get_context_loader(context, path) if loader and loader.strategy: strat = self._get_strategy(loader.strategy) else: strat = self.strategy strat.create_row_processor( context, query_entity, path, loader, mapper, result, adapter, populators, ) def do_init(self) -> None: self._strategies = {} self.strategy = self._get_strategy(self.strategy_key) def post_instrument_class(self, mapper: Mapper[Any]) -> None: if ( not self.parent.non_primary and not mapper.class_manager._attr_has_impl(self.key) ): self.strategy.init_class_attribute(mapper) _all_strategies: collections.defaultdict[ Type[MapperProperty[Any]], Dict[_StrategyKey, Type[LoaderStrategy]] ] = collections.defaultdict(dict) @classmethod def strategy_for(cls, **kw: Any) -> Callable[[_TLS], _TLS]: def decorate(dec_cls: _TLS) -> _TLS: # ensure each subclass of the strategy has its # own _strategy_keys collection if "_strategy_keys" not in dec_cls.__dict__: dec_cls._strategy_keys = [] key = tuple(sorted(kw.items())) cls._all_strategies[cls][key] = dec_cls dec_cls._strategy_keys.append(key) return dec_cls return decorate @classmethod def _strategy_lookup( cls, requesting_property: MapperProperty[Any], *key: Any ) -> Type[LoaderStrategy]: requesting_property.parent._with_polymorphic_mappers for prop_cls in cls.__mro__: if prop_cls in cls._all_strategies: if TYPE_CHECKING: assert issubclass(prop_cls, MapperProperty) strategies = cls._all_strategies[prop_cls] try: return strategies[key] except KeyError: pass for property_type, strats in cls._all_strategies.items(): if key in strats: intended_property_type = property_type actual_strategy = strats[key] break else: intended_property_type = None actual_strategy = None raise orm_exc.LoaderStrategyException( cls, requesting_property, intended_property_type, actual_strategy, key, ) class ORMOption(ExecutableOption): """Base class for option objects that are passed to ORM queries. These options may be consumed by :meth:`.Query.options`, :meth:`.Select.options`, or in a more general sense by any :meth:`.Executable.options` method. They are interpreted at statement compile time or execution time in modern use. The deprecated :class:`.MapperOption` is consumed at ORM query construction time. .. versionadded:: 1.4 """ __slots__ = () _is_legacy_option = False propagate_to_loaders = False """if True, indicate this option should be carried along to "secondary" SELECT statements that occur for relationship lazy loaders as well as attribute load / refresh operations. """ _is_core = False _is_user_defined = False _is_compile_state = False _is_criteria_option = False _is_strategy_option = False class CompileStateOption(HasCacheKey, ORMOption): """base for :class:`.ORMOption` classes that affect the compilation of a SQL query and therefore need to be part of the cache key. .. note:: :class:`.CompileStateOption` is generally non-public and should not be used as a base class for user-defined options; instead, use :class:`.UserDefinedOption`, which is easier to use as it does not interact with ORM compilation internals or caching. :class:`.CompileStateOption` defines an internal attribute ``_is_compile_state=True`` which has the effect of the ORM compilation routines for SELECT and other statements will call upon these options when a SQL string is being compiled. As such, these classes implement :class:`.HasCacheKey` and need to provide robust ``_cache_key_traversal`` structures. The :class:`.CompileStateOption` class is used to implement the ORM :class:`.LoaderOption` and :class:`.CriteriaOption` classes. .. versionadded:: 1.4.28 """ __slots__ = () _is_compile_state = True def process_compile_state(self, compile_state: ORMCompileState) -> None: """Apply a modification to a given :class:`.ORMCompileState`. This method is part of the implementation of a particular :class:`.CompileStateOption` and is only invoked internally when an ORM query is compiled. """ def process_compile_state_replaced_entities( self, compile_state: ORMCompileState, mapper_entities: Sequence[_MapperEntity], ) -> None: """Apply a modification to a given :class:`.ORMCompileState`, given entities that were replaced by with_only_columns() or with_entities(). This method is part of the implementation of a particular :class:`.CompileStateOption` and is only invoked internally when an ORM query is compiled. .. versionadded:: 1.4.19 """ class LoaderOption(CompileStateOption): """Describe a loader modification to an ORM statement at compilation time. .. versionadded:: 1.4 """ __slots__ = () def process_compile_state_replaced_entities( self, compile_state: ORMCompileState, mapper_entities: Sequence[_MapperEntity], ) -> None: self.process_compile_state(compile_state) class CriteriaOption(CompileStateOption): """Describe a WHERE criteria modification to an ORM statement at compilation time. .. versionadded:: 1.4 """ __slots__ = () _is_criteria_option = True def get_global_criteria(self, attributes: Dict[str, Any]) -> None: """update additional entity criteria options in the given attributes dictionary. """ class UserDefinedOption(ORMOption): """Base class for a user-defined option that can be consumed from the :meth:`.SessionEvents.do_orm_execute` event hook. """ __slots__ = ("payload",) _is_legacy_option = False _is_user_defined = True propagate_to_loaders = False """if True, indicate this option should be carried along to "secondary" Query objects produced during lazy loads or refresh operations. """ def __init__(self, payload: Optional[Any] = None): self.payload = payload @util.deprecated_cls( "1.4", "The :class:`.MapperOption class is deprecated and will be removed " "in a future release. For " "modifications to queries on a per-execution basis, use the " ":class:`.UserDefinedOption` class to establish state within a " ":class:`.Query` or other Core statement, then use the " ":meth:`.SessionEvents.before_orm_execute` hook to consume them.", constructor=None, ) class MapperOption(ORMOption): """Describe a modification to a Query""" __slots__ = () _is_legacy_option = True propagate_to_loaders = False """if True, indicate this option should be carried along to "secondary" Query objects produced during lazy loads or refresh operations. """ def process_query(self, query: Query[Any]) -> None: """Apply a modification to the given :class:`_query.Query`.""" def process_query_conditionally(self, query: Query[Any]) -> None: """same as process_query(), except that this option may not apply to the given query. This is typically applied during a lazy load or scalar refresh operation to propagate options stated in the original Query to the new Query being used for the load. It occurs for those options that specify propagate_to_loaders=True. """ self.process_query(query) class LoaderStrategy: """Describe the loading behavior of a StrategizedProperty object. The ``LoaderStrategy`` interacts with the querying process in three ways: * it controls the configuration of the ``InstrumentedAttribute`` placed on a class to handle the behavior of the attribute. this may involve setting up class-level callable functions to fire off a select operation when the attribute is first accessed (i.e. a lazy load) * it processes the ``QueryContext`` at statement construction time, where it can modify the SQL statement that is being produced. For example, simple column attributes will add their represented column to the list of selected columns, a joined eager loader may establish join clauses to add to the statement. * It produces "row processor" functions at result fetching time. These "row processor" functions populate a particular attribute on a particular mapped instance. """ __slots__ = ( "parent_property", "is_class_level", "parent", "key", "strategy_key", "strategy_opts", ) _strategy_keys: ClassVar[List[_StrategyKey]] def __init__( self, parent: MapperProperty[Any], strategy_key: _StrategyKey ): self.parent_property = parent self.is_class_level = False self.parent = self.parent_property.parent self.key = self.parent_property.key self.strategy_key = strategy_key self.strategy_opts = dict(strategy_key) def init_class_attribute(self, mapper: Mapper[Any]) -> None: pass def setup_query( self, compile_state: ORMCompileState, query_entity: _MapperEntity, path: AbstractEntityRegistry, loadopt: Optional[_LoadElement], adapter: Optional[ORMAdapter], **kwargs: Any, ) -> None: """Establish column and other state for a given QueryContext. This method fulfills the contract specified by MapperProperty.setup(). StrategizedProperty delegates its setup() method directly to this method. """ def create_row_processor( self, context: ORMCompileState, query_entity: _MapperEntity, path: AbstractEntityRegistry, loadopt: Optional[_LoadElement], mapper: Mapper[Any], result: Result[Any], adapter: Optional[ORMAdapter], populators: _PopulatorDict, ) -> None: """Establish row processing functions for a given QueryContext. This method fulfills the contract specified by MapperProperty.create_row_processor(). StrategizedProperty delegates its create_row_processor() method directly to this method. """ def __str__(self) -> str: return str(self.parent_property)