Method __init__

lib/sqlalchemy/dialects/mysql/enumerated.py:122–183

Construct a SET. E.g.:: Column("myset", SET("foo", "bar", "baz")) The list of potential values is required in the case that this set will be used to generate DDL for a table, or if the :paramref:`.SET.retrieve_as_bitwise` flag is set to True. :pa

(self, *values: str, **kw: Any)

    __visit_name__ = "SET"

    def __init__(self, *values: str, **kw: Any):
        """Construct a SET.

        E.g.::

          Column("myset", SET("foo", "bar", "baz"))

        The list of potential values is required in the case that this
        set will be used to generate DDL for a table, or if the
        :paramref:`.SET.retrieve_as_bitwise` flag is set to True.

        :param values: The range of valid values for this SET. The values
          are not quoted, they will be escaped and surrounded by single
          quotes when generating the schema.

        :param convert_unicode: Same flag as that of
         :paramref:`.String.convert_unicode`.

        :param collation: same as that of :paramref:`.String.collation`

        :param charset: same as that of :paramref:`.VARCHAR.charset`.

        :param ascii: same as that of :paramref:`.VARCHAR.ascii`.

        :param unicode: same as that of :paramref:`.VARCHAR.unicode`.

        :param binary: same as that of :paramref:`.VARCHAR.binary`.

        :param retrieve_as_bitwise: if True, the data for the set type will be
          persisted and selected using an integer value, where a set is coerced
          into a bitwise mask for persistence.  MySQL allows this mode which
          has the advantage of being able to store values unambiguously,
          such as the blank string ``''``.   The datatype will appear
          as the expression ``col + 0`` in a SELECT statement, so that the
          value is coerced into an integer value in result sets.
          This flag is required if one wishes
          to persist a set that can store the blank string ``''`` as a value.

          .. warning::

            When using :paramref:`.mysql.SET.retrieve_as_bitwise`, it is
            essential that the list of set values is expressed in the
            **exact same order** as exists on the MySQL database.

        """
        self.retrieve_as_bitwise = kw.pop("retrieve_as_bitwise", False)
        self.values = tuple(values)
        if not self.retrieve_as_bitwise and "" in values:
            raise exc.ArgumentError(
                "Can't use the blank value '' in a SET without "
                "setting retrieve_as_bitwise=True"
            )
        if self.retrieve_as_bitwise:
            self._inversed_bitmap: dict[str, int] = {
                value: 2**idx for idx, value in enumerate(self.values)
            }
            self._bitmap: dict[int, str] = {
                2**idx: value for idx, value in enumerate(self.values)