JSON serializable Problem in Django When Try to Use Session

Question

I try to add a cart process in my ecommerce prject which is built with Python Django Framework. But when i try to check data the visitor is authenticated or not and try to return data from model manager I face a json serializable problem. In Bellow i give you the sample code,

Here is my view file:

from django.shortcuts import render
from .models import Cart
from django.core import serializers

# Create your views here.

def cart_create(user=None):
    cart_obj = Cart.objects.create(user=None)
    print('New Cart Created')
    return cart_obj

def cart_home(request):

    cart_id = request.session.get("cart_id", None)
    qs = Cart.objects.filter(id=cart_id)
    if qs.count() == 1:
      print("Cart Id exists")
      cart_obj = qs.first()
      if request.user.is_authenticated and cart_obj.user is None:
        cart_obj.user = request.user
        cart_obj.save()
    else:
      #cart_obj = cart_create()
      cart_obj = Cart.objects.new(user=request.user)
      request.session['cart_id'] = cart_obj


    return render(request, "carts/home.html")

Here Is my Model File:

from django.db import models
from django.conf import settings
from products.models import Product
from django.core.serializers import serialize

User = settings.AUTH_USER_MODEL

# Create your models here.

class CartManager(models.Manager):

    def new(self, user=None):
        print(user)
        user_obj = None
        if user is not None:
            if user.is_authenticated:
                user_obj = user
        return self.model.objects.create(user=user)




class Cart(models.Model):
    user = models.ForeignKey(User, null=True, blank=True, on_delete=models.CASCADE)
    products = models.ManyToManyField(Product, blank=True)
    total = models.DecimalField(default=0.00, max_digits=100, decimal_places=2)
    updated = models.DateTimeField(auto_now=True)
    timestamp = models.DateTimeField(auto_now_add=True)

    objects = CartManager()

    def __str__(self):
        return str(self.id)

Here is the generated Error:

I have no idea why generated this error. I have try to many possible ways to solve this problem. But can not solve it . Can anyone help me..

Answer 1

Replace line request.session['cart_id'] = cart_obj with request.session['cart_id'] = cart_obj.id