SerializedRelatedField

class SerializedRelatedField(relations.RelatedField):
    """
    A read-write field that uses a serializer when reading the relation but
    expects the pk to be provided when creating or updating.
    """

    default_error_messages = {
        'does_not_exist': _('Object with pk={value} does not exist.'),
        'invalid': _('Invalid value.'),
        'needs_id': _('The data provided is missing the "id" field.'),
    }

    def __init__(self, serializer, **kwargs):
        self.serializer = serializer
        super(SerializedRelatedField, self).__init__(**kwargs)

    def to_internal_value(self, data):
        if 'id' not in data:
            self.fail('needs_id')
        pk = data['id']
        try:
            return self.get_queryset().get(pk=pk)
        except ObjectDoesNotExist:
            self.fail('does_not_exist', value=smart_text(pk))
        except (TypeError, ValueError):
            self.fail('invalid')

    def to_representation(self, obj):
        return self.serializer(obj).data