Class LambdaElement

lib/sqlalchemy/sql/lambdas.py:154–424

A SQL construct where the state is stored as an un-invoked lambda. The :class:`_sql.LambdaElement` is produced transparently whenever passing lambda expressions into SQL constructs, such as:: stmt = select(table).where(lambda: table.c.col == parameter) The :class:`_sql.LambdaE

class LambdaElement(elements.ClauseElement):
    """A SQL construct where the state is stored as an un-invoked lambda.

    The :class:`_sql.LambdaElement` is produced transparently whenever
    passing lambda expressions into SQL constructs, such as::

        stmt = select(table).where(lambda: table.c.col == parameter)

    The :class:`_sql.LambdaElement` is the base of the
    :class:`_sql.StatementLambdaElement` which represents a full statement
    within a lambda.

    .. versionadded:: 1.4

    .. seealso::

        :ref:`engine_lambda_caching`

    """

    __visit_name__ = "lambda_element"

    _is_lambda_element = True

    _traverse_internals = [
        ("_resolved", visitors.InternalTraversal.dp_clauseelement)
    ]

    _transforms: Tuple[_CloneCallableType, ...] = ()

    _resolved_bindparams: List[BindParameter[Any]]
    parent_lambda: Optional[StatementLambdaElement] = None
    closure_cache_key: Union[Tuple[Any, ...], Literal[CacheConst.NO_CACHE]]
    role: Type[SQLRole]
    _rec: Union[AnalyzedFunction, NonAnalyzedFunction]
    fn: _AnyLambdaType
    tracker_key: Tuple[CodeType, ...]

    def __repr__(self):
        return "%s(%r)" % (
            self.__class__.__name__,
            self.fn.__code__,
        )

    def __init__(
        self,
        fn: _LambdaType,
        role: Type[SQLRole],
        opts: Union[Type[LambdaOptions], LambdaOptions] = LambdaOptions,
        apply_propagate_attrs: Optional[ClauseElement] = None,
    ):
        self.fn = fn
        self.role = role
        self.tracker_key = (fn.__code__,)
        self.opts = opts

        if apply_propagate_attrs is None and (role is roles.StatementRole):
            apply_propagate_attrs = self