500 ошибка Django Rest Frameworks Serializer

новичок. Я следую учебнику по React+Django (создание магазина), в котором мы используем Django RestFrameworks (и это мой первый раз, когда я его использую). Мы используем сериализаторы с JWT-токенами для аутентификации. Проблема в том, что когда я пытаюсь создать новый "заказ" на странице, я получаю ошибку 500:

Мой файл serializers.py выглядит следующим образом:

from rest_framework import serializers
from django.contrib.auth.models import User
from rest_framework_simplejwt.tokens import RefreshToken
from .models import Product, Order, OrderItem, ShippingAddress



class UserSerializer(serializers.ModelSerializer):
    name = serializers.SerializerMethodField(read_only = True)
    isAdmin = serializers.SerializerMethodField(read_only = True)
    class Meta:
        model = User
        fields= ['id', 'first_name','email', 'name', 'isAdmin']
    
    def get_isAdmin(self, obj):
        return obj.is_staff
    
    def get_name(self, obj):
          name = obj.first_name
          if name == '':
              name = obj.email
          return name 

class UserSerializerWithToken(UserSerializer):
    token = serializers.SerializerMethodField(read_only = True)
    class Meta:
        model=User
        fields = ['id', 'username', 'email', 'name', 'isAdmin', 'token']
        
    def get_token(self, obj):
        token = RefreshToken.for_user(obj)
        return str(token.access_token)
        

class ProductSerializer(serializers.ModelSerializer):
    class Meta:
        model = Product
        fields= '__all__'
        
class ShippingAddressSerializer(serializers.ModelSerializer):
    class Meta:
        model = ShippingAddress
        fields= '__all__'
        
class OrderItemSerializer(serializers.ModelSerializer):
    class Meta:
        model = OrderItem
        fields= '__all__'

class OrderSerializer(serializers.ModelSerializer):
    orderItems = serializers.SerializerMethodField(read_only = True) #formerly orders
    shippingAddress = serializers.SerializerMethodField(read_only = True)
    user = serializers.SerializerMethodField(read_only = True)
    class Meta:
        model = Order
        fields= '__all__'
    
    def get_orderItems(self,obj): #former get_orders
        items = obj.orderitem_set.all()
        serializer = OrderItemSerializer(items, many = True)
        return serializer.data
    
    def get_shippingAddress(self,obj):
        try:
            address = ShippingAddressSerializer(obj.shippingAddress, many=False) #we can do it like this because this is  a 1:1 field
        except:
            address = False
            
        return address
    
    def get_user(self,obj):
        user =User.objects.all() #previously obj.user.all(), but that gave an error
        serializer = UserSerializer(user, many = False)
        return serializer.data

my user_views.py:

from django.shortcuts import render
from django.contrib.auth.hashers import make_password
from rest_framework.decorators import api_view, permission_classes
from rest_framework.permissions import IsAuthenticated, IsAdminUser
from rest_framework.response import Response
from rest_framework_simplejwt.serializers import TokenObtainPairSerializer
from rest_framework_simplejwt.views import TokenObtainPairView
from rest_framework import status

from base.models import User
from base.serializers import  UserSerializer, UserSerializerWithToken


class MyTokenObtainPairSerializer(TokenObtainPairSerializer):
    def validate(self, attrs):
        data = super().validate(attrs)
        serializer = UserSerializerWithToken(self.user).data
        for key, value in serializer.items():
            data[key]=value
        return data
 
class MyTokenObtainPairView(TokenObtainPairView):
    serializer_class = MyTokenObtainPairSerializer
    
    
@api_view(['POST'])    
def registerUser(request):
    data=request.data
    try:
        user=User.objects.create(
            first_name = data['first_name'],
            #last_name= data['last_name'], this was causing error: fields didn't match
            username = data['email'], 
            email = data['email'],
            password = make_password(data['password'])
    )
            
        serializer = UserSerializerWithToken(user, many=False)
        return Response(serializer.data)
    except:
        message={'detail':'User with this email already exists'}
        return Response(message, status=status.HTTP_400_BAD_REQUEST)
 

@api_view(['PUT'])
@permission_classes([IsAuthenticated])
def updateUserProfile(request):
    user = request.user 
    serializer = UserSerializerWithToken(user, many=False)
    
    data =request.data 
    user.first_name=data['first_name']
    user.username=data['email']
    user.email=data['email']
    if data['password'] != ' ' :
        user.password =  make_password(data['password']) 
    
    user.save() 
    
    return Response(serializer.data)

    
@api_view(['GET'])
@permission_classes([IsAuthenticated])
def getUserProfile(request):
    user = request.user 
    serializer = UserSerializer(user, many=False)
    return Response(serializer.data)

@api_view(['GET'])
@permission_classes([IsAdminUser])
def getUsers(request):
    users = User.objects.all() 
    serializer = UserSerializer(users, many=True)
    return Response(serializer.data)

В этом учебнике мы используем модель Django User по умолчанию.

Пожалуйста, может кто-нибудь подсказать мне, что я делаю не так? Заранее большое спасибо

def get_user(self,obj):
    serializer = UserSerializer(obj.user)
    return serializer.data

 def get_user(self,obj):
    serializer = UserSerializer(obj.user)
    return serializer.data