Allows composing serializers together in DRF.

composed_serializer.py

def composed_serializer(serializer):
    """
    A decorator which, when applied to a serializer composed of
    multiple other serializers, generates a Meta that merges the fields.
    :param serializer: The composed class to generate Meta for.
    :return: A new class with correctly defined Meta.
    """

    combined_fields = {x for x in itertools.chain(*(x.Meta.fields for x in serializer.__bases__))}
    if serializer.Meta:
        combined_fields |= set(serializer.Meta.fields)

    class ComposedSerializer(serializer):
        class Meta:
            fields = tuple(combined_fields)
            model = serializer.__base__.Meta.model

    ComposedSerializer.__name__ = serializer.__name__
    ComposedSerializer.__doc__ = serializer.__doc__

    return ComposedSerializer