Why am I getting a circular import error with django? - django

Question

This question seems to be asked before but none of the answers I came across solve my issue.
I'm getting the following error when I try running the server with python manage.py runserver:
django.core.exceptions.ImproperlyConfigured: The included URLconf 'tutorial.urls' does not appear to have any patterns in it. If you see valid patterns in the file then the issue is probably caused by a circular import.
The error goes away if I change models.py so that my Item class does not extend models.Model.
These are the relevant files:
models.py
from django.db import models
from django.contrib.auth.models import User
class Item(models.Model):
name = models.CharField(max_length=255)
owner = models.ForeignKey(User, on_delete=models.CASCADE)
price = models.DecimalField(decimal_places=2)
def __str__(self):
return self.name
serializers.py
from rest_framework import serializers
from django.contrib.auth.models import User, Group
from .models import Item
class UserSerializer(serializers.HyperlinkedModelSerializer):
class Meta:
model = User
fields = ('url', 'username', 'email', 'groups')
class GroupSerializer(serializers.HyperlinkedModelSerializer):
class Meta:
model = Group
fields = ('url', 'name')
class ItemSerializer(serializers.HyperlinkedModelSerializer):
class Meta:
model = Item
fields = ('url', 'name', 'owner', 'price')
views.py
from django.contrib.auth.models import User, Group
from rest_framework import viewsets
from .serializers import UserSerializer, GroupSerializer, ItemSerializer
from .models import Item
class UserViewSet(viewsets.ModelViewSet):
"""
API endpoint that allows users to be viewed or edited.
"""
queryset = User.objects.all().order_by('-date_joined')
serializer_class = UserSerializer
class GroupViewSet(viewsets.ModelViewSet):
"""
API endpoint that allows groups to be viewed or edited.
"""
queryset = Group.objects.all()
serializer_class = GroupSerializer
class ItemViewSet(viewsets.ModelViewSet):
"""
API endpoint that allows items to be viewed or edited.
"""
queryset = Item.objects.all()
serializer_class = ItemSerializer
urls.py
from django.urls import include, path
from rest_framework import routers
from tutorial.quickstart import views
router = routers.DefaultRouter()
router.register('users', views.UserViewSet)
router.register('groups', views.GroupViewSet)
router.register('items', views.ItemViewSet)
urlpatterns = [
path('', include(router.urls)),
path('api-auth/', include('rest_framework.urls', namespace='rest_framework'))
]