Class FetchedValue

lib/sqlalchemy/sql/schema.py:4354–4412

A marker for a transparent database-side default. Use :class:`.FetchedValue` when the database is configured to provide some automatic default for a column. E.g.:: Column("foo", Integer, FetchedValue()) Would indicate that some trigger or default generator will create

@inspection._self_inspects
class FetchedValue(SchemaEventTarget):
    """A marker for a transparent database-side default.

    Use :class:`.FetchedValue` when the database is configured
    to provide some automatic default for a column.

    E.g.::

        Column("foo", Integer, FetchedValue())

    Would indicate that some trigger or default generator
    will create a new value for the ``foo`` column during an
    INSERT.

    .. seealso::

        :ref:`triggered_columns`

    """

    is_server_default = True
    reflected = False
    has_argument = False
    is_clause_element = False
    is_identity = False
    _is_monotonic_fn = False

    column: Optional[Column[Any]]

    def __init__(self, for_update: bool = False) -> None:
        self.for_update = for_update

    def _as_for_update(self, for_update: bool) -> FetchedValue:
        if for_update == self.for_update:
            return self
        else:
            return self._clone(for_update)

    def _copy(self) -> FetchedValue:
        return FetchedValue(self.for_update)

    def _clone(self, for_update: bool) -> Self:
        n = self.__class__.__new__(self.__class__)
        n.__dict__.update(self.__dict__)
        n.__dict__.pop("column", None)
        n.for_update = for_update
        return n

    def _set_parent(self, parent: SchemaEventTarget, **kw: Any) -> None:
        column = parent
        assert isinstance(column, Column)
        self.column = column
        if self.for_update:
            self.column.server_onupdate = self
        else:
            self.column.server_default = self

    def __repr__(self) -> str: