Method __init__

lib/sqlalchemy/sql/schema.py:3082–3206

r""" Construct a column-level FOREIGN KEY. The :class:`_schema.ForeignKey` object when constructed generates a :class:`_schema.ForeignKeyConstraint` which is associated with the parent :class:`_schema.Table` object's collection of constraints. :param

(
        self,
        column: _DDLColumnReferenceArgument,
        _constraint: Optional[ForeignKeyConstraint] = None,
        use_alter: bool = False,
        name: _ConstraintNameArgument = None,
        onupdate: Optional[str] = None,
        ondelete: Optional[str] = None,
        deferrable: Optional[bool] = None,
        initially: Optional[str] = None,
        link_to_name: bool = False,
        match: Optional[str] = None,
        info: Optional[_InfoType] = None,
        comment: Optional[str] = None,
        _unresolvable: bool = False,
        **dialect_kw: Any,
    )

    _colspec: Union[str, Column[Any]]

    def __init__(
        self,
        column: _DDLColumnReferenceArgument,
        _constraint: Optional[ForeignKeyConstraint] = None,
        use_alter: bool = False,
        name: _ConstraintNameArgument = None,
        onupdate: Optional[str] = None,
        ondelete: Optional[str] = None,
        deferrable: Optional[bool] = None,
        initially: Optional[str] = None,
        link_to_name: bool = False,
        match: Optional[str] = None,
        info: Optional[_InfoType] = None,
        comment: Optional[str] = None,
        _unresolvable: bool = False,
        **dialect_kw: Any,
    ):
        r"""
        Construct a column-level FOREIGN KEY.

        The :class:`_schema.ForeignKey` object when constructed generates a
        :class:`_schema.ForeignKeyConstraint`
        which is associated with the parent
        :class:`_schema.Table` object's collection of constraints.

        :param column: A single target column for the key relationship. A
            :class:`_schema.Column` object or a column name as a string:
            ``tablename.columnkey`` or ``schema.tablename.columnkey``.
            ``columnkey`` is the ``key`` which has been assigned to the column
            (defaults to the column name itself), unless ``link_to_name`` is
            ``True`` in which case the rendered name of the column is used.

        :param name: Optional string. An in-database name for the key if
            `constraint` is not provided.

        :param onupdate: Optional string. If set, emit ON UPDATE <value> when
            issuing DDL for this constraint. Typical values include CASCADE,
            DELETE and RESTRICT.

            .. seealso::

                :ref:`on_update_on_delete`

        :param ondelete: Optional string. If set, emit ON DELETE <value> when
            issuing DDL for this constraint. Typical values include CASCADE,
            SET NULL and RESTRICT.  Some dialects may allow for additional
            syntaxes.

            .. seealso::

                :ref:`on_update_on_delete`

        :param deferrable: Optional bool. If set, emit DEFERRABLE or NOT
            DEFERRABLE when issuing DDL for this constraint.

        :param initially: Optional string. If set, emit INITIALLY <value> when
            issuing DDL for this constraint.