Django session: Object of type is not JSON serializable?

Question

Django

Good evening. Ran into a similar problem with Django session(serialization error) . Created 2 applications under the basket and under the favorites. If I disable 1 of them in settings, then the other one works without errors. Or if you add a product to your favorites and a basket - it works, otherwise I get an error

raise TypeError(f'Object of type {o.__class__.__name__} '
TypeError: Object of type Goods is not JSON serializable

# Ошибка: корзина пустая, 1 товар в избранном
{'1': {}} # print(self.session.get('favorites'))
{} # print(self.session.get('cart'))

Saving and deleting works. The error occurs during the output, I assume that in __iter__
services.py

from apps.goods.models import Goods

class Favorites(object):

  def __init__(self, request):
    """ Initialize the favorites """
    self.session = request.session
    favorites = self.session.get('favorites')

    if not favorites:
      favorites = self.session['favorites'] = {}
    self.favorites = favorites

  def save(self):
    """ 
    Mark the session as "modified" to make sure it gets saved
    """
    # добавил строку из решения по ссылке но не помогло
    # self.session['favorites'] = self.favorites = self.session.get('favorites', []) 
    
    self.session.modified = True

  def add(self, goods):
    """
    Add a goods to the favorite
    """
    goods_id = str(goods.id)
    if goods_id not in self.favorites:
      self.favorites[goods_id] = {}
    self.save()

  def remove(self, goods):
    """
    Remove a goods from the favorite
    """
    goods_id = str(goods.id)
    if goods_id in self.favorites:
      del self.favorites[goods_id]
      self.save()                          

  def __iter__(self):
    """
    Iterate over the items in the favorites and get the goods 
    from the database.
    """
    goods_ids = self.favorites.keys()    
    products = Goods.objects.filter(id__in=goods_ids)
    favorites = self.favorites.copy()
    for product in products:
      favorites[str(product.id)]['goods'] = product        
  
    for item in favorites.values():
        yield item

  def __len__(self):
    return len(self.favorites)

views.py

from django.shortcuts import render, get_object_or_404, redirect
from django.views.decorators.http import require_POST
from apps.goods.models import Goods
from .services import Favorites

def favorites(request):
  favorites = Favorites(request)
  return render(request, 'wishlist/favorites.html', {'favorites': favorites})

def add_favorites(request, goods_id):
  favorites = Favorites(request)
  goods = get_object_or_404(Goods, id=goods_id)
  favorites.add(goods = goods)
  return redirect('favorites')

def remove_favorites(request, goods_id):
  favorites = Favorites(request)
  goods = get_object_or_404(Goods, id=goods_id)
  favorites.remove(goods)
  return redirect('favorites')

In services for the basket is similar, but with the addition of additional data

apps.cart.services

from decimal import Decimal
from apps.goods.models import Goods


class Cart(object):

  def __init__(self, request):
    """ Initialize the cart. """
    self.session = request.session
    cart = self.session.get('cart')
    if not cart:
        # save an empty cart in the session
        cart = self.session['cart'] = {}
    self.cart = cart


  def add(self, goods, size, quantity=1, update_quantity=False):
      """
      Add a goods to the cart or update its quantity.
      """
      goods_id = str(goods.id) + size
      if goods_id not in self.cart:
          self.cart[goods_id] = {'id': str(goods.id),
                                 'quantity': 0, 
                                 'price': goods.price,
                                 'size': size}
      if update_quantity:
          self.cart[goods_id]['quantity'] = quantity
      else:
          self.cart[goods_id]['quantity'] += quantity
      self.save()


  def save(self):
    """ 
    Mark the session as "modified" to make sure it gets saved
    """
    # строка из решения по ссылке не помогло
    # self.session['cart'] = self.cart = self.session.get('cart', [])
    self.session.modified = True


  def remove(self, goods, size):
    """
    Remove a goods from the cart
    """
    goods_id = str(goods.id) + size
    if goods_id in self.cart:
      del self.cart[goods_id]
      self.save()
  

  def __iter__(self):
    """
    Iterate over the items in the cart and get the goods 
    from the database.
    """
    goods_ids = list()
    for key in self.cart.values():
      goods_ids.append(key['id'])

    # get the product objects and add them to the cart
    products = Goods.objects.filter(id__in=goods_ids)
    cart = self.cart.copy()
    for product in products:
        for el in self.cart.values():
          id = str(product.id)
          if el['id'] == id:
            cart[ id + el['size'] ]['goods'] = product
            self.cart[ id + el['size'] ]['price'] = product.price
  
    for item in cart.values():
        item['total_price'] = item['price'] * item['quantity']
        yield item
  

  def __len__(self):
    """
    Count all items in the cart.
    """
    return sum(item['quantity'] for item in self.cart.values())


  def get_total_price(self):
    return sum(Decimal(item['price']) * item['quantity'] for item in self.cart.values())


  def clear(self):
    """
    Remove cart from session
    """ 
    del self.session['cart']
    self.save()

I don't understand why there is a conflict?

Answer 1

You add an ORM model object to the session. The JSON session is serialized. Model object not serializing to JSON (out of the blue)