sqlalchemy.orm.interfaces.LoaderStrategy

class documentation

class LoaderStrategy: (source)

Known subclasses: sqlalchemy.orm.strategies.AbstractRelationshipLoader, sqlalchemy.orm.strategies.ColumnLoader, sqlalchemy.orm.strategies.DeferredColumnLoader, sqlalchemy.orm.strategies.DoNothingLoader, sqlalchemy.orm.strategies.UninstrumentedColumnLoader

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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.

Method __init__ Undocumented
Method __str__ Undocumented
Method create_row_processor Establish row processing functions for a given QueryContext.
Method init_class_attribute Undocumented
Method setup_query Establish column and other state for a given QueryContext.
Class Variable __slots__ Undocumented
Instance Variable is_class_level Undocumented
Instance Variable key Undocumented
Instance Variable parent Undocumented
Instance Variable parent_property Undocumented
Instance Variable strategy_key Undocumented
Instance Variable strategy_opts Undocumented
Class Variable _strategy_keys Undocumented
def __init__(self, parent: MapperProperty[Any], strategy_key: _StrategyKey): (source)
overridden in sqlalchemy.orm.strategies.AbstractRelationshipLoader, sqlalchemy.orm.strategies.ColumnLoader, sqlalchemy.orm.strategies.DeferredColumnLoader, sqlalchemy.orm.strategies.UninstrumentedColumnLoader

Undocumented

def __str__(self) -> str: (source)

Undocumented

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): (source)
overridden in sqlalchemy.orm.strategies.ColumnLoader, sqlalchemy.orm.strategies.DeferredColumnLoader, sqlalchemy.orm.strategies.ImmediateLoader, sqlalchemy.orm.strategies.JoinedLoader, sqlalchemy.orm.strategies.LazyLoader, sqlalchemy.orm.strategies.NoLoader, sqlalchemy.orm.strategies.SelectInLoader, sqlalchemy.orm.strategies.SubqueryLoader, sqlalchemy.orm.strategies.UninstrumentedColumnLoader

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 init_class_attribute(self, mapper: Mapper[Any]): (source)
overridden in sqlalchemy.orm.strategies.ColumnLoader, sqlalchemy.orm.strategies.DeferredColumnLoader, sqlalchemy.orm.strategies.ImmediateLoader, sqlalchemy.orm.strategies.JoinedLoader, sqlalchemy.orm.strategies.LazyLoader, sqlalchemy.orm.strategies.NoLoader, sqlalchemy.orm.strategies.SelectInLoader, sqlalchemy.orm.strategies.SubqueryLoader, sqlalchemy.orm.writeonly.WriteOnlyLoader

Undocumented

def setup_query(self, compile_state: ORMCompileState, query_entity: _MapperEntity, path: AbstractEntityRegistry, loadopt: Optional[_LoadElement], adapter: Optional[ORMAdapter], **kwargs: Any): (source)
overridden in sqlalchemy.orm.strategies.ColumnLoader, sqlalchemy.orm.strategies.DeferredColumnLoader, sqlalchemy.orm.strategies.JoinedLoader, sqlalchemy.orm.strategies.UninstrumentedColumnLoader

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.

__slots__: tuple[str, ...] = (source)
overridden in sqlalchemy.orm.strategies.AbstractRelationshipLoader, sqlalchemy.orm.strategies.ColumnLoader, sqlalchemy.orm.strategies.DeferredColumnLoader, sqlalchemy.orm.strategies.UninstrumentedColumnLoader

Undocumented

is_class_level: bool = (source)
overridden in sqlalchemy.orm.strategies.ColumnLoader, sqlalchemy.orm.strategies.DeferredColumnLoader, sqlalchemy.orm.strategies.LazyLoader, sqlalchemy.orm.strategies.NoLoader, sqlalchemy.orm.writeonly.WriteOnlyLoader

Undocumented

key = (source)

Undocumented

parent = (source)

Undocumented

parent_property = (source)
overridden in sqlalchemy.orm.strategies.LazyLoader

Undocumented

strategy_key = (source)

Undocumented

strategy_opts = (source)

Undocumented

_strategy_keys: ClassVar[List[_StrategyKey]] = (source)

Undocumented