text: from django.conf import settings
  from rest_framework import generics, status
  from rest_framework.permissions import IsAdminUser, IsAuthenticated
  from rest_framework.response import Response
  
  from members.permissions import IsProjectAdmin, IsProjectStaffAndReadOnly
  
  from ..models import Project
  from ..serializers import ProjectPolymorphicSerializer
  
  
  class ProjectList(generics.ListCreateAPIView):
      serializer_class = ProjectPolymorphicSerializer
      pagination_class = None
  
      def get_permissions(self):
          if self.request.method == 'GET':
              self.permission_classes = [IsAuthenticated, ]
          else:
              self.permission_classes = [IsAuthenticated & IsAdminUser]
          return super().get_permissions()
  
      def get_queryset(self):
          return Project.objects.filter(role_mappings__user=self.request.user)
  
      def perform_create(self, serializer):
          serializer.save(created_by=self.request.user)
  
      def delete(self, request, *args, **kwargs):
          delete_ids = request.data['ids']
          projects = Project.objects.filter(
              role_mappings__user=self.request.user,
              role_mappings__role__name=settings.ROLE_PROJECT_ADMIN,
              pk__in=delete_ids
          )
          # Todo: I want to use bulk delete.
          # But it causes the constraint error.
          # See https://github.com/django-polymorphic/django-polymorphic/issues/229
          for project in projects:
              project.delete()
          return Response(status=status.HTTP_204_NO_CONTENT)
  
  
  class ProjectDetail(generics.RetrieveUpdateDestroyAPIView):
      queryset = Project.objects.all()
      serializer_class = ProjectPolymorphicSerializer
      lookup_url_kwarg = 'project_id'
      permission_classes = [IsAuthenticated & (IsProjectAdmin | IsProjectStaffAndReadOnly)]
  