Class _InsertSentinelColumnDefault

lib/sqlalchemy/sql/schema.py:3824–3859

Default generator that's specific to the use of a "sentinel" column when using the insertmanyvalues feature. This default is used as part of the :func:`_schema.insert_sentinel` construct.

class _InsertSentinelColumnDefault(ColumnDefault):
    """Default generator that's specific to the use of a "sentinel" column
    when using the insertmanyvalues feature.

    This default is used as part of the :func:`_schema.insert_sentinel`
    construct.

    """

    is_sentinel = True
    for_update = False
    arg = None

    def __new__(cls) -> _InsertSentinelColumnDefault:
        return object.__new__(cls)

    def __init__(self) -> None:
        pass

    def _set_parent(self, parent: SchemaEventTarget, **kw: Any) -> None:
        col = cast("Column[Any]", parent)
        if not col._insert_sentinel:
            raise exc.ArgumentError(
                "The _InsertSentinelColumnDefault may only be applied to a "
                "Column marked as insert_sentinel=True"
            )
        elif not col.nullable:
            raise exc.ArgumentError(
                "The _InsertSentinelColumnDefault may only be applied to a "
                "Column that is nullable"
            )

        super()._set_parent(parent, **kw)

    def _copy(self) -> _InsertSentinelColumnDefault:
        return _InsertSentinelColumnDefault()


_SQLExprDefault = Union["ColumnElement[Any]", "TextClause"]