Объект 'type' не является итерируемым django-rest-framework

Я новичок в разработке мобильных приложений и пытаюсь сделать свое первое приложение с react-native и Django rest-framework в качестве бэкенда. Когда я пытаюсь запустить сервер и получить доступ к любой модели через django-rest-framework, я получаю "TypeError: 'type' object is not iterable." Я пытался найти способ решения этой проблемы, но все способы, которые я нашел в интернете, не помогли.

Вот мой код:

models.py-

from django.db import models
from django.contrib.auth.models import User
from django.core.validators import MaxValueValidator, MinValueValidator




class Movie(models.Model):
    title = models.CharField(max_length=32)
    description = models.TextField()

    def no_of_ratings(self):
        ratings = Rating.objects.filter(movie=self)
        return len(ratings)

    def avg_rating(self):
        sum = 0
        ratings = Rating.objects.filter(movie=self)
        for rating in ratings:
            sum += rating.stars
            if len(ratings) > 0:
             return sum / len(ratings)
            else:
        return 0


class Rating(models.Model):
    movie = models.ForeignKey(Movie, on_delete=models.CASCADE)
    user = models.ForeignKey(User, on_delete=models.CASCADE)
    stars = models.IntegerField(validators=[MinValueValidator(1), MaxValueValidator(5)])

class Meta:
    unique_together = (('user', 'movie'))
    index_together = (('user', 'movie'))

serializers.py-

from rest_framework import serializer
from .models import Movie, Rating
from django.contrib.auth.models import User
from rest_framework.authtoken.models import Token


class MovieSerializer(serializers.ModelSerializer):
    class Meta:
        model = Movie
        fields =('id', 'title', 'description', 'no_of_ratings', 'avg_rating')

class RatingSerializer(serializers.ModelSerializer):
    class Meta:
        model = Rating
        fields =('id', 'stars', 'user', 'movie')

class UserSerializer(serializers.ModelSerializer):
    class Meta:
        model = User
        fields =('id', 'username', 'password')
        extra_kwargs = {'password': {'write_only': True, 'required': True}}

    def create(self, validated_data):
        user = User.objects.create_user(**validated_data)
        Token.objects.create(user=user)
        return user

views.py-

from django.shortcuts import render
from rest_framework import viewsets, status
from .serializers import MovieSerializer, RatingSerializer, UserSerializer
from .models import Movie, Rating
from rest_framework.response import Response
from rest_framework.decorators import action
from django.contrib.auth.models import User
from rest_framework.authentication import TokenAuthentication 
from rest_framework.permissions import IsAuthenticated, AllowAny
from rest_framework.permissions import IsAuthenticatedOrReadOnly, BasePermission

# Create your views here.


class UserViewSet(viewsets.ModelViewSet):
    queryset = User.objects.all()
    serializer_class = UserSerializer


class MovieViewSet(viewsets.ModelViewSet):

    queryset = Movie.objects.all()
    serializer_class = MovieSerializer
    authentication_classes = (TokenAuthentication)
    permission_classes = (IsAuthenticated)

    @action(detail=True, methods=['POST'])
    def rate_movie(self, request, pk=None):
        if 'stars' in request.data:

            movie = Movie.objects.get(id=pk)
            stars = request.data['stars']
            user = request.user
        

            try: 
                rating = Rating.objects.get(user=user.id, movie=movie.id) 
                rating.stars = stars
                rating.save()
                serializer = RatingSerializer(rating, mamy=False)
                Rating.objects.create(user=user, movie=movie, stars=stars)
                response = {'message': 'Rating Updated', 'result': serializer.data}
            except:
            
                rating = Rating.objects.create(user=user, movie=movie, stars=stars)
                serializer = RatingSerializer(rating, mamy=False)
                response = {'message': 'Rating created', 'result': serializer.data}
                return Response(response, status=status.HTTP_200_OK)

        else:
            response = {'message': 'you need to provide stars'}
            return Response(response, status=status.HTTP_400_BAD_REQUEST)



class RatingViewSet(viewsets.ModelViewSet):
    queryset = Rating.objects.all()
    serializer_class = RatingSerializer
    authentication_classes = (TokenAuthentication)
    permission_classes = (AllowAny)

    def update(self, request, *args, **kwargs):
         response = {'message': 'You cant update rating like that'}
         return Response(response, status=status.HTTP_400_BAD_REQUEST)

    def create(self, request, *args, **kwargs):
         response = {'message': 'You cant create rating like that'}
         return Response(response, status=status.HTTP_400_BAD_REQUEST)

Как я могу исправить эту ошибку?

#...
authentication_classes = (TokenAuthentication,)
permission_classes = (AllowAny,)
#...