Using selected_related() in nested serializers - django

Question

I've been using select_related() to speed up a large DRF call with great success, but I've hit a wall.
My main serializer references two other serializers, and one of those references yet another serializer. I'm unsure as how to implement prefetching in the second level serializer.
serializer.py
class DocumentsThinSerializer(serializers.ModelSerializer):
class Meta:
model = Documents
fields = ('confirmed', )
class PersonThinSerializer(serializers.ModelSerializer):
documents = DocumentsThinSerializer()
class Meta:
model = Person
fields = ('name', 'age', 'gender')
class EventThinSerializer(serializers.ModelSerializer):
day = DayThinSerializer()
person = PersonThinSerializer()
#staticmethod
def setup_eager_loading(queryset):
return queryset.select_related('day', 'person')
class Meta:
model = Event
views.py
class EventList(generics.ListAPIView):
authentication_classes = (SessionAuthentication, BasicAuthentication)
permission_classes = (IsAuthenticated,)
queryset = Event.objects.all()
serializer_class = EventThinSerializer
def get_queryset(self):
return self.get_serializer_class().setup_eager_loading(queryset)
As you can see, I'm using the static method setup_eager_loading() to get things going, but I can't find a queryset hook for my PersonThinSerializer() to get the speedup when accessing the DocumentsThinSerializer() in the same way.

Answer 1

Assuming Documents has a foreign key to Person, you should be able to add "person__documents" to your queryset.select_related in EventThinSerializer.setup_eager_loading:
class EventThinSerializer(serializers.ModelSerializer):
day = DayThinSerializer()
person = PersonThinSerializer()
#staticmethod
def setup_eager_loading(queryset):
return queryset.select_related('day', 'person', 'person__documents')