How to resolve "AssertionError. The `.create()` method does not support writable nested fields by default"?

Question

Django

Model:

class Burger(models.Model):
    name = models.CharField(max_length=64)
    description = models.TextField(max_length=256)
    price = models.DecimalField(max_digits=3,decimal_places=0)


class Order(models.Model):
    count = models.IntegerField(default=0)
    address = models.OneToOneField(Address,default='')
    phone_number = models.IntegerField(default=0,blank=False)
    burgers = models.ForeignKey(Burger, null=True)

Serializer:

class BurgerSerializer(serializers.ModelSerializer):
    class Meta:
        model = Burger
        fields = ['name', 'description', 'price']

class OrderSerializer(serializers.ModelSerializer):
    address = AddressSerializer()
    burgers = BurgerSerializer(read_only=True)

    class Meta:
        model = Order
        fields = ['count', 'phone_number', 'address', 'burgers']

View:

class OrderList(generics.ListCreateAPIView):
    # GET request to list all entrys
    queryset = Order.objects.all()
    serializer_class = OrderSerializer

    def perform_create(self, serializer):
        instance = serializer.save()
        session_id = self.request.session.session_key
        burger_ids = SessionOrder.objects.filter(session_id=session_id)
        for item in burger_ids:
            burger = Burger.objects.get(id=item.burger_id)
            instance.burgers_set.add(burger)

What could be the reason ?

Answer 1

www.django-rest-framework.org/topics/3.0-announcem...
# first link in search results