sqlalchemy.orm.interfaces.StrategizedProperty

class documentation

class StrategizedProperty(MapperProperty[_T]): (source)

Known subclasses: sqlalchemy.orm.properties.ColumnProperty, sqlalchemy.orm.properties.RelationshipProperty

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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.

Class Method strategy_for Undocumented
Method create_row_processor Produce row processing functions and append to the given set of populators lists.
Method do_init Perform subclass-specific initialization post-mapper-creation steps.
Method post_instrument_class Perform instrumentation adjustments that need to occur after init() has completed.
Method setup Called by Query for the purposes of constructing a SQL statement.
Class Variable __slots__ Undocumented
Class Variable inherit_cache Indicate if this :class:`.HasCacheKey` instance should make use of the cache key generation scheme used by its immediate superclass.
Class Variable strategy_key Undocumented
Class Variable strategy_wildcard_key Undocumented
Instance Variable strategy Undocumented
Class Method _strategy_lookup Undocumented
Method _get_context_loader Undocumented
Method _get_strategy Undocumented
Method _memoized_attr__default_path_loader_key Undocumented
Method _memoized_attr__wildcard_token Undocumented
Class Variable _all_strategies Undocumented
Instance Variable _strategies Undocumented

Inherited from MapperProperty:

Method __init__ Undocumented
Method __repr__ Undocumented
Method cascade_iterator Iterate through instances related to the given instance for a particular 'cascade', starting with this MapperProperty.
Method init Called after all mappers are created to assemble relationships between mappers and perform other post-mapper-creation initialization steps.
Method instrument_class Hook called by the Mapper to the property to initiate instrumentation of the class attribute managed by this MapperProperty.
Method merge Merge the attribute represented by this ``MapperProperty`` from source to destination object.
Method set_parent Set the parent mapper that references this MapperProperty.
Class Variable cascade Undocumented
Class Variable comparator The :class:`_orm.PropComparator` instance that implements SQL expression construction on behalf of this mapped attribute.
Class Variable doc optional documentation string
Class Variable info Info dictionary associated with the object, allowing user-defined data to be associated with this :class:`.InspectionAttr`.
Class Variable is_property Part of the InspectionAttr interface; states this object is a mapper property.
Class Variable key name of class attribute
Instance Variable parent the :class:`.Mapper` managing this property.
Property class_attribute Return the class-bound descriptor corresponding to this :class:`.MapperProperty`.
Method _memoized_attr_info Info dictionary associated with the object, allowing user-defined data to be associated with this :class:`.InspectionAttr`.
Class Variable _cache_key_traversal Undocumented
Class Variable _is_relationship Undocumented
Class Variable _links_to_entity True if this MapperProperty refers to a mapped entity.
Instance Variable _attribute_options behavioral options for ORM-enabled Python attributes
Instance Variable _configure_finished Undocumented
Instance Variable _configure_started Undocumented
Instance Variable _has_dataclass_arguments Undocumented

Inherited from HasCacheKey (via MapperProperty):

Class Method _generate_cache_attrs generate cache key dispatcher for a new class.
Class Method _generate_cache_key_for_object Undocumented
Method _gen_cache_key return an optional cache key.
Method _generate_cache_key return a cache key.
Class Variable _generated_cache_key_traversal Undocumented
Class Variable _hierarchy_supports_caching private attribute which may be set to False to prevent the inherit_cache warning from being emitted for a hierarchy of subclasses.
Class Variable _is_has_cache_key Undocumented

Inherited from TypingOnly (via MapperProperty, HasCacheKey, _DCAttributeOptions, _MappedAttribute):

Method __init_subclass__ Undocumented

Inherited from InspectionAttr (via MapperProperty, HasCacheKey, _DCAttributeOptions, _MappedAttribute, TypingOnly, InspectionAttrInfo):

Class Variable is_aliased_class True if this object is an instance of :class:`.AliasedClass`.
Class Variable is_attribute True if this object is a Python :term:`descriptor`.
Class Variable is_bundle True if this object is an instance of :class:`.Bundle`.
Class Variable is_clause_element True if this object is an instance of :class:`_expression.ClauseElement`.
Class Variable is_instance True if this object is an instance of :class:`.InstanceState`.
Class Variable is_mapper True if this object is an instance of :class:`_orm.Mapper`.
Class Variable is_selectable Return True if this object is an instance of :class:`_expression.Selectable`.
Class Variable _is_internal_proxy True if this object is an internal proxy object.

Inherited from MemoizedSlots (via MapperProperty, HasCacheKey, _DCAttributeOptions, _MappedAttribute, TypingOnly, InspectionAttrInfo, InspectionAttr):

Method __getattr__ Undocumented
Method _fallback_getattr Undocumented
@classmethod
def strategy_for(cls, **kw: Any) -> Callable[[_TLS], _TLS]: (source)

Undocumented

def create_row_processor(self, context: ORMCompileState, query_entity: _MapperEntity, path: AbstractEntityRegistry, mapper: Mapper[Any], result: Result[Any], adapter: Optional[ORMAdapter], populators: _PopulatorDict): (source)
overrides sqlalchemy.orm.interfaces.MapperProperty.create_row_processor

Produce row processing functions and append to the given set of populators lists.

def do_init(self): (source)
overrides sqlalchemy.orm.interfaces.MapperProperty.do_init
overridden in sqlalchemy.orm.properties.ColumnProperty, sqlalchemy.orm.properties.RelationshipProperty

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]): (source)
overrides sqlalchemy.orm.interfaces.MapperProperty.post_instrument_class

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 setup(self, context: ORMCompileState, query_entity: _MapperEntity, path: AbstractEntityRegistry, adapter: Optional[ORMAdapter], **kwargs: Any): (source)
overrides sqlalchemy.orm.interfaces.MapperProperty.setup

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.

__slots__: tuple[str, ...] = (source)
overrides sqlalchemy.orm.interfaces.MapperProperty.__slots__
overridden in sqlalchemy.orm.properties.ColumnProperty

Undocumented

inherit_cache: bool = (source)
overrides sqlalchemy.sql.cache_key.HasCacheKey.inherit_cache
overridden in sqlalchemy.orm.properties.ColumnProperty, sqlalchemy.orm.properties.RelationshipProperty

Indicate if this :class:`.HasCacheKey` instance should make use of the cache key generation scheme used by its immediate superclass. The attribute defaults to ``None``, which indicates that a construct has not yet taken into account whether or not its appropriate for it to participate in caching; this is functionally equivalent to setting the value to ``False``, except that a warning is also emitted. This flag can be set to ``True`` on a particular class, if the SQL that corresponds to the object does not change based on attributes which are local to this class, and not its superclass. .. seealso:: :ref:`compilerext_caching` - General guideslines for setting the :attr:`.HasCacheKey.inherit_cache` attribute for third-party or user defined SQL constructs.

strategy_key: _StrategyKey = (source)
overridden in sqlalchemy.orm.properties.ColumnProperty, sqlalchemy.orm.properties.RelationshipProperty

Undocumented

strategy_wildcard_key: ClassVar[str] = (source)

Undocumented

strategy = (source)

Undocumented

@classmethod
def _strategy_lookup(cls, requesting_property: MapperProperty[Any], *key: Any) -> Type[LoaderStrategy]: (source)

Undocumented

def _get_context_loader(self, context: ORMCompileState, path: AbstractEntityRegistry) -> Optional[_LoadElement]: (source)

Undocumented

def _get_strategy(self, key: _StrategyKey) -> LoaderStrategy: (source)

Undocumented

def _memoized_attr__default_path_loader_key(self) -> Tuple[str, Tuple[str]]: (source)

Undocumented

def _memoized_attr__wildcard_token(self) -> Tuple[str]: (source)

Undocumented

_all_strategies: collections.defaultdict[Type[MapperProperty[Any]], Dict[_StrategyKey, Type[LoaderStrategy]]] = (source)

Undocumented

_strategies: dict = (source)

Undocumented