Class TypeCoerce

lib/sqlalchemy/sql/elements.py:3756–3817

Represent a Python-side type-coercion wrapper. :class:`.TypeCoerce` supplies the :func:`_expression.type_coerce` function; see that function for usage details. .. seealso:: :func:`_expression.type_coerce` :func:`.cast`

class TypeCoerce(WrapsColumnExpression[_T]):
    """Represent a Python-side type-coercion wrapper.

    :class:`.TypeCoerce` supplies the :func:`_expression.type_coerce`
    function; see that function for usage details.

    .. seealso::

        :func:`_expression.type_coerce`

        :func:`.cast`

    """

    __visit_name__ = "type_coerce"

    _traverse_internals: _TraverseInternalsType = [
        ("clause", InternalTraversal.dp_clauseelement),
        ("type", InternalTraversal.dp_type),
    ]

    clause: ColumnElement[Any]
    type: TypeEngine[_T]

    def __init__(
        self,
        expression: _ColumnExpressionArgument[Any],
        type_: _TypeEngineArgument[_T],
    ):
        self.type = type_api.to_instance(type_)
        self.clause = coercions.expect(
            roles.ExpressionElementRole,
            expression,
            type_=self.type,
            apply_propagate_attrs=self,
        )

    @util.ro_non_memoized_property
    def _from_objects(self) -> List[FromClause]:
        return self.clause._from_objects

    @HasMemoized.memoized_attribute
    def typed_expression(self):
        if isinstance(self.clause, BindParameter):
            bp = self.clause._clone()
            bp.type = self.type
            return bp
        else:
            return self.clause

    @property
    def wrapped_column_expression(self):
        return self.clause

    def self_group(
        self, against: Optional[OperatorType] = None
    ) -> TypeCoerce[_T]:
        grouped = self.clause.self_group(against=against)