Class FrameClause

lib/sqlalchemy/sql/elements.py:4632–4752

Indicate the 'rows' 'range' or 'group' field of a window function, e.g. using :class:`.Over`. .. versionadded:: 2.1

class FrameClause(ClauseElement):
    """Indicate the 'rows' 'range' or 'group' field of a window function,
    e.g. using :class:`.Over`.

    .. versionadded:: 2.1

    """

    __visit_name__ = "frame_clause"

    _traverse_internals: _TraverseInternalsType = [
        ("lower_bind", InternalTraversal.dp_clauseelement),
        ("upper_bind", InternalTraversal.dp_clauseelement),
        ("lower_type", InternalTraversal.dp_plain_obj),
        ("upper_type", InternalTraversal.dp_plain_obj),
    ]

    def __init__(
        self,
        start: Any,
        end: Any,
        start_frame_type: FrameClauseType,
        end_frame_type: FrameClauseType,
        _validate: bool = True,
    ) -> None:
        """Creates a new FrameClause specifying the bounds of a window frame.

        :param start: The start value.
        :param end: The end value.
        :param start_frame_type: The :class:`FrameClauseType` for the
            start value.
        :param end_frame_type: The :class:`FrameClauseType` for the end value.
        """
        self.lower_bind = self._as_literal(start)
        self.upper_bind = self._as_literal(end)
        self.lower_type = FrameClauseType(start_frame_type)
        self.upper_type = FrameClauseType(end_frame_type)
        if _validate:
            if (
                self.lower_type in _require_none
                and self.lower_bind is not None
            ):
                raise exc.ArgumentError(
                    "Cannot specify a value for start with frame type "
                    f"{self.lower_type.name}"
                )
            if (
                self.upper_type in _require_none
                and self.upper_bind is not None
            ):
                raise exc.ArgumentError(
                    "Cannot specify a value for end with frame type "
                    f"{self.upper_type.name}"
                )

    @classmethod
    def _as_literal(cls, value: Any) -> BindParameter[Any] | None:
        if value is None: