import typing import marshmallow class Sequence(marshmallow.fields.List): """ A sequence field, basically an immutable version of the list field. """ def _deserialize( # type: ignore[override] self, value: typing.Any, attr: typing.Any, data: typing.Any, **kwargs: typing.Any, ) -> typing.Optional[typing.Sequence[typing.Any]]: optional_list = super()._deserialize(value, attr, data, **kwargs) return None if optional_list is None else tuple(optional_list) class Set(marshmallow.fields.List): """ A set field. A set is an unordered/mutable collection of unique elements, same for frozenset except it's immutable. Notes: Beware the a Set guarantees uniqueness in the resulting list but in return the item's order will be random. So if the order matters, use a List or Sequence ! """ def __init__( self, cls_or_instance: typing.Union[marshmallow.fields.Field, type], frozen: bool = False, **kwargs, ): super().__init__(cls_or_instance, **kwargs) self.set_type: typing.Type[typing.Union[frozenset, set]] = ( frozenset if frozen else set ) def _deserialize( # type: ignore[override] self, value: typing.Any, attr: typing.Any, data: typing.Any, **kwargs: typing.Any, ) -> typing.Union[typing.Set[typing.Any], typing.FrozenSet[typing.Any], None]: optional_list = super()._deserialize(value, attr, data, **kwargs) return None if optional_list is None else self.set_type(optional_list)