Function query_expression

lib/sqlalchemy/orm/_orm_constructors.py:2260–2300

Indicate an attribute that populates from a query-time SQL expression. :param default_expr: Optional SQL expression object that will be used in all cases if not assigned later with :func:`_orm.with_expression`. .. versionadded:: 1.2 .. seealso:: :ref:`orm_queryguide_w

(
    default_expr: _ORMColumnExprArgument[_T] = sql.null(),
    *,
    repr: Union[_NoArg, bool] = _NoArg.NO_ARG,  # noqa: A002
    compare: Union[_NoArg, bool] = _NoArg.NO_ARG,  # noqa: A002
    expire_on_flush: bool = True,
    info: Optional[_InfoType] = None,
    doc: Optional[str] = None,
)

def query_expression(
    default_expr: _ORMColumnExprArgument[_T] = sql.null(),
    *,
    repr: Union[_NoArg, bool] = _NoArg.NO_ARG,  # noqa: A002
    compare: Union[_NoArg, bool] = _NoArg.NO_ARG,  # noqa: A002
    expire_on_flush: bool = True,
    info: Optional[_InfoType] = None,
    doc: Optional[str] = None,
) -> MappedSQLExpression[_T]:
    """Indicate an attribute that populates from a query-time SQL expression.

    :param default_expr: Optional SQL expression object that will be used in
        all cases if not assigned later with :func:`_orm.with_expression`.

    .. versionadded:: 1.2

    .. seealso::

        :ref:`orm_queryguide_with_expression` - background and usage examples

    """
    prop = MappedSQLExpression(
        default_expr,
        attribute_options=_AttributeOptions(
            False,
            repr,
            _NoArg.NO_ARG,
            _NoArg.NO_ARG,
            compare,
            _NoArg.NO_ARG,
            _NoArg.NO_ARG,
            _NoArg.NO_ARG,
        ),
        expire_on_flush=expire_on_flush,
        info=info,
        doc=doc,
        _assume_readonly_dc_attributes=True,
    )

    prop.strategy_key = (("query_expression", True),)
    return prop


def clear_mappers() -> None: