Class Load

lib/sqlalchemy/orm/strategy_options.py:969–1334

Represents loader options which modify the state of a ORM-enabled :class:`_sql.Select` or a legacy :class:`_query.Query` in order to affect how various mapped attributes are loaded. The :class:`_orm.Load` object is in most cases used implicitly behind the scenes when one makes use o

class Load(_AbstractLoad):
    """Represents loader options which modify the state of a
    ORM-enabled :class:`_sql.Select` or a legacy :class:`_query.Query` in
    order to affect how various mapped attributes are loaded.

    The :class:`_orm.Load` object is in most cases used implicitly behind the
    scenes when one makes use of a query option like :func:`_orm.joinedload`,
    :func:`_orm.defer`, or similar.   It typically is not instantiated directly
    except for in some very specific cases.

    .. seealso::

        :ref:`orm_queryguide_relationship_per_entity_wildcard` - illustrates an
        example where direct use of :class:`_orm.Load` may be useful

    """

    __slots__ = (
        "path",
        "context",
        "additional_source_entities",
    )

    _traverse_internals = [
        ("path", visitors.ExtendedInternalTraversal.dp_has_cache_key),
        (
            "context",
            visitors.InternalTraversal.dp_has_cache_key_list,
        ),
        ("propagate_to_loaders", visitors.InternalTraversal.dp_boolean),
        (
            "additional_source_entities",
            visitors.InternalTraversal.dp_has_cache_key_list,
        ),
    ]
    _cache_key_traversal = None

    path: PathRegistry
    context: Tuple[_LoadElement, ...]
    additional_source_entities: Tuple[_InternalEntityType[Any], ...]

    def __init__(self, entity: _EntityType[Any]):
        insp = cast("Union[Mapper[Any], AliasedInsp[Any]]", inspect(entity))
        insp._post_inspect

        self.path = insp._path_registry
        self.context = ()
        self.propagate_to_loaders = False
        self.additional_source_entities = ()

    def __str__(self) -> str:
        return f"Load({self.path[0]})"

    @classmethod
    def _construct_for_existing_path(
        cls, path: AbstractEntityRegistry
    ) -> Load:
        load = cls.__new__(cls)