AttributeError: 'DocumentBaseSerializer' object has no attribute 'get_document_type'

[allinws]

Getting an error due to that my "base serializer" don't hold the functions that my "sub-serializers" (that are inheriting from the base serializer contain) - bug?

View

    from .shared import *
    from drf_spectacular.utils import extend_schema_field
    from drf_spectacular.types import OpenApiTypes


    class DocumentsSerializer(BaseSerializer):
        pk = serializers.UUIDField(source='id', format='hex_verbose')
        common_type_name = serializers.CharField(source='common-type-name')
        originator_name = serializers.CharField(source='originator-short-name')
        disclosed_at = serializers.SerializerMethodField()
        headline = serializers.CharField()
        subject_companies = ListCharField(source='subject-companies')
        document_type = serializers.CharField(source='document-type')
        publishing_status = serializers.CharField(source='publishing-status')

        @extend_schema_field(OpenApiTypes.BOOL)
        def get_disclosed_at(self, obj):
            return Helpers._get_date_time(obj['disclosed-at'])

    class DocumentBaseSerializer(BaseSerializer):
        pk = serializers.UUIDField(source='id', format='hex_verbose')
        originator = OriginatorSerializer()
        subject_companies = SubjectCompaniesSerializer(many=True,source='subject-companies')
        language_specific_content = LanguageSpecificContentSerializer(many=True, source='language-specific-content')
        is_in_use = serializers.BooleanField(source='is-in-use')
        disclosed_at = serializers.SerializerMethodField()
        document_type = serializers.SerializerMethodField()
        disabled = serializers.SerializerMethodField()
        descriptions_as_html = ListCharField(source='descriptions-as-html', required=False)
        delay_publishing_until = serializers.CharField(source='delay-publishing-until')
        publishing_type = serializers.CharField(source='publishing-type')
        version = serializers.IntegerField()

        def get_disabled(self,obj):
            return Helpers._get_disabled(obj)

        @extend_schema_field(OpenApiTypes.BOOL)
        def get_disclosed_at(self, obj):
            return Helpers._get_date_time(obj['disclosed-at'])
            

    class GetArticleOfAssociationSerializer(DocumentBaseSerializer):
        def get_document_type(self, obj):
            return 'article-of-association'


    class GetCorporateGovernanceReportSerializer(DocumentBaseSerializer):
        def get_document_type(self, obj):
            return 'corporate-governance-report'


    class GetGeneralMeetingProtocolSerializer(DocumentBaseSerializer):
        def get_document_type(self, obj):
            return 'general-meeting-protocol'


    class GetPresentationSerializer(DocumentBaseSerializer):
        def get_document_type(self, obj):
            return 'presentation'


    class GetPublicOfferDocumentSerializer(DocumentBaseSerializer):
        def get_document_type(self, obj):
            return 'public-offer-document'

Full traceback

Internal Server Error: /api/schema/
Traceback (most recent call last):
File "/home/username/project/env/lib/python3.6/site-packages/django/core/handlers/exception.py", line 34, in inner
    response = get_response(request)
File "/home/username/project/env/lib/python3.6/site-packages/django/core/handlers/base.py", line 115, in _get_response
    response = self.process_exception_by_middleware(e, request)
File "/home/username/project/env/lib/python3.6/site-packages/django/core/handlers/base.py", line 113, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/home/username/project/env/lib/python3.6/site-packages/django/views/decorators/csrf.py", line 54, in wrapped_view
    return view_func(*args, **kwargs)
File "/home/username/project/env/lib/python3.6/site-packages/django/views/generic/base.py", line 71, in view
    return self.dispatch(request, *args, **kwargs)
File "/home/username/project/env/lib/python3.6/site-packages/rest_framework/views.py", line 505, in dispatch
    response = self.handle_exception(exc)
File "/home/username/project/env/lib/python3.6/site-packages/rest_framework/views.py", line 465, in handle_exception
    self.raise_uncaught_exception(exc)
File "/home/username/project/env/lib/python3.6/site-packages/rest_framework/views.py", line 476, in raise_uncaught_exception
    raise exc
File "/home/username/project/env/lib/python3.6/site-packages/rest_framework/views.py", line 502, in dispatch
    response = handler(request, *args, **kwargs)
File "/home/username/project/env/lib/python3.6/site-packages/drf_spectacular/views.py", line 67, in get
    return self._get_schema_response(request)
File "/home/username/project/env/lib/python3.6/site-packages/drf_spectacular/views.py", line 74, in _get_schema_response
    return Response(generator.get_schema(request=request, public=self.serve_public))
File "/home/username/project/env/lib/python3.6/site-packages/drf_spectacular/generators.py", line 262, in get_schema
    paths=self.parse(request, public),
File "/home/username/project/env/lib/python3.6/site-packages/drf_spectacular/generators.py", line 234, in parse
    path, path_regex, path_prefix, method, self.registry
File "/home/username/project/env/lib/python3.6/site-packages/drf_spectacular/openapi.py", line 88, in get_operation
    operation['responses'] = self._get_response_bodies()
File "/home/username/project/env/lib/python3.6/site-packages/drf_spectacular/openapi.py", line 1117, in _get_response_bodies
    return {'200': self._get_response_for_code(response_serializers, '200')}
File "/home/username/project/env/lib/python3.6/site-packages/drf_spectacular/openapi.py", line 1173, in _get_response_for_code
    component = self.resolve_serializer(serializer, 'response')
File "/home/username/project/env/lib/python3.6/site-packages/drf_spectacular/openapi.py", line 1318, in resolve_serializer
    component.schema = self._map_serializer(serializer, direction)
File "/home/username/project/env/lib/python3.6/site-packages/drf_spectacular/openapi.py", line 766, in _map_serializer
    schema = self._map_basic_serializer(serializer, direction)
File "/home/username/project/env/lib/python3.6/site-packages/drf_spectacular/openapi.py", line 841, in _map_basic_serializer
    schema = self._map_serializer_field(field, direction)
File "/home/username/project/env/lib/python3.6/site-packages/drf_spectacular/openapi.py", line 695, in _map_serializer_field
    method = getattr(field.parent, field.method_name)
AttributeError: 'DocumentBaseSerializer' object has no attribute 'get_document_type'

[tfranzel]

Strictly speaking, I don't think it is a bug. Sure, we should catch that error and do a fallback, but the problem remains.

Option 1:

DocumentBaseSerializer is not a valid Serializer in itself (due to missing methods). Somehow spectacular tries to resolve the DocumentBaseSerializer because its specified somewhere (maybe as serializer_class or annotation). If you remove all direct usages of DocumentBaseSerializer and replace them with the sub-serializers, the issue should disappear. Your DocumentBaseSerializer serves a "abstract base class" and should not be used directly. Spectacular only does this because it is used directly somewhere in your code.

Option 2:

If that is not what you need I would recommend something like this:

class DocumentBaseSerializer(BaseSerializer):
    ....
    document_type = serializers.SerializerMethodField()
    ...
    # the literal just just as an example. you can also do "-> str:"
    def get_document_type(self, obj) -> typing.Literal['public-offer-document', 'presentation', 'article-of-association',...]:
        raise NotImplementedError()

[allinws]

Thank you for the quick response, your second alternative worked perfectly :) Was happy to find your repo and will recommend it to others as it seems to work great.