Class MappedColumn

lib/sqlalchemy/orm/properties.py:511–934

Maps a single :class:`_schema.Column` on a class. :class:`_orm.MappedColumn` is a specialization of the :class:`_orm.ColumnProperty` class and is oriented towards declarative configuration. To construct :class:`_orm.MappedColumn` objects, use the :func:`_orm.mapped_column` cons

class MappedColumn(
    _IntrospectsAnnotations,
    _MapsColumns[_T],
    _DeclarativeMapped[_T],
):
    """Maps a single :class:`_schema.Column` on a class.

    :class:`_orm.MappedColumn` is a specialization of the
    :class:`_orm.ColumnProperty` class and is oriented towards declarative
    configuration.

    To construct :class:`_orm.MappedColumn` objects, use the
    :func:`_orm.mapped_column` constructor function.

    .. versionadded:: 2.0


    """

    __slots__ = (
        "column",
        "_creation_order",
        "_sort_order",
        "foreign_keys",
        "_has_nullable",
        "_has_insert_default",
        "deferred",
        "deferred_group",
        "deferred_raiseload",
        "active_history",
        "_attribute_options",
        "_has_dataclass_arguments",
        "_use_existing_column",
    )

    deferred: Union[_NoArg, bool]
    deferred_raiseload: bool
    deferred_group: Optional[str]

    column: Column[_T]
    foreign_keys: Optional[Set[ForeignKey]]
    _attribute_options: _AttributeOptions

    def __init__(self, *arg: Any, **kw: Any):
        self._attribute_options = attr_opts = kw.pop(
            "attribute_options", _DEFAULT_ATTRIBUTE_OPTIONS
        )

        self._use_existing_column = kw.pop("use_existing_column", False)

        self._has_dataclass_arguments = (
            attr_opts is not None
            and attr_opts != _DEFAULT_ATTRIBUTE_OPTIONS
            and any(
                attr_opts[i] is not _NoArg.NO_ARG
                for i, attr in enumerate(attr_opts._fields)
                if attr != "dataclasses_default"
            )