old_contents: from rest_framework import generics
  
  from .models import PartCategory, Part, PartParameter
  from .serializers import PartSerializer
  from .serializers import PartCategoryBriefSerializer, PartCategoryDetailSerializer
  from .serializers import PartParameterSerializer
  
  
  class PartDetail(generics.RetrieveAPIView):
  
      queryset = Part.objects.all()
      serializer_class = PartSerializer
  
  
  class PartParameters(generics.ListAPIView):
  
      def get_queryset(self):
          part_id = self.kwargs['pk']
          return PartParameter.objects.filter(part=part_id)
  
      serializer_class = PartParameterSerializer
  
  
  class PartList(generics.ListAPIView):
  
      queryset = Part.objects.all()
      serializer_class = PartSerializer
  
  
  class PartCategoryDetail(generics.RetrieveAPIView):
      """ Return information on a single PartCategory
      """
      queryset = PartCategory.objects.all()
      serializer_class = PartCategoryDetailSerializer
  
  
  class PartCategoryList(generics.ListAPIView):
      """ Return a list of all top-level part categories.
      Categories are considered "top-level" if they do not have a parent
      """
      queryset = PartCategory.objects.filter(parent=None)
      serializer_class = PartCategoryBriefSerializer
  
new_contents: from rest_framework import generics
  
  from .models import PartCategory, Part, PartParameter
  from .serializers import PartSerializer
  from .serializers import PartCategoryBriefSerializer, PartCategoryDetailSerializer
  from .serializers import PartParameterSerializer
  
  
  class PartDetail(generics.RetrieveAPIView):
  
      queryset = Part.objects.all()
      serializer_class = PartSerializer
  
  
  class PartParameters(generics.ListAPIView):
  
      def get_queryset(self):
          part_id = self.kwargs['pk']
          return PartParameter.objects.filter(part=part_id)
  
      serializer_class = PartParameterSerializer
  
  
  class PartList(generics.ListAPIView):
  
      queryset = Part.objects.all()
      serializer_class = PartSerializer
  
  
  class PartCategoryDetail(generics.RetrieveAPIView):
      """ Return information on a single PartCategory
      """
      queryset = PartCategory.objects.all()
      serializer_class = PartCategoryDetailSerializer
  
  
  class PartCategoryList(generics.ListAPIView):
      """ Return a list of all top-level part categories.
      Categories are considered "top-level" if they do not have a parent
      """
      queryset = PartCategory.objects.filter(parent=None)
      serializer_class = PartCategoryDetailSerializer
  
subject: Fix for part category API