Обработка корзины, или почему генератор не работает

product = get_object_or_404(Dishes, id=pk)
        cart = Cart(request)
        cart.add(item=product)

class Cart(object):
 
    def __init__(self, request):
 
        self.session = request.session
        cart = self.session.get('cart')
        if not cart:
            cart = request.session['cart'] = {}
        self.cart = cart
 
    def add(self, item):
        product_id = item.id
        if product_id not in self.cart:
            self.cart[product_id] = {'quantity': 1,
                                     'price': str(item.price),
                                     'name': str(item.name)}
        self.session['cart'] = self.cart
        self.session.modified = True
 
    def __iter__(self):
        product_ids = self.cart.keys()
        filtered_product = Dishes.objects.filter(id__in=product_ids)
        for obj in filtered_product:
            self.cart[str(obj.id)]['obj'] = obj
 
        for item in self.cart.values():
            yield item

TypeError at /8/
Object of type Dishes is not JSON serializable
Request Method: GET
Request URL:    http://127.0.0.1:8000/8/
Django Version: 3.0.7
Exception Type: TypeError
Exception Value:    
Object of type Dishes is not JSON serializable
Exception Location: C:\Users\ikunk\AppData\Local\Programs\Python\Python38-32\lib\json\encoder.py in default, line 179
Python Executable:  G:\f\TMP\venv\iiko\Scripts\python.exe
Python Version: 3.8.1
Python Path:    
['G:\\f\\TMP\\iiko',
 'C:\\Users\\ikunk\\AppData\\Local\\Programs\\Python\\Python38-32\\python38.zip',
 'C:\\Users\\ikunk\\AppData\\Local\\Programs\\Python\\Python38-32\\DLLs',
 'C:\\Users\\ikunk\\AppData\\Local\\Programs\\Python\\Python38-32\\lib',
 'C:\\Users\\ikunk\\AppData\\Local\\Programs\\Python\\Python38-32',
 'G:\\f\\TMP\\venv\\iiko',
 'G:\\f\\TMP\\venv\\iiko\\lib\\site-packages',
 'G:\\f\\TMP\\venv\\iiko\\lib\\site-packages\\setuptools-40.8.0-py3.8.egg']
Server time:    Пн, 13 Июл 2020 10:21:45 +0000

{% for c in cart %}
                        {% with item=c.obj %}
                        <p>CartList - {{item.name}}</p>
                        {% endwith %}
                        {% endfor %}

class MainDetailView(View):
 
    def get(self, request, pk):
        template_name = 'dishes/detail.html'
        product_list = Dishes.objects.filter(id=pk)
        product = get_object_or_404(Dishes, id=pk)
        cart = Cart(request)
        cart.add(item=product)
 
        return render(request, template_name, context={'product_list': product_list, 'cart': cart})
 
    def post(self, request, pk):
        if request.method == 'POST':
            #submitbutton = request.POST.get("submit")
            alist = Dishes.objects.filter(id=pk)
            return render(request, 'cart/cart.html', {'alist': alist})
        else:
            return redirect('./')

class MainCartView(TemplateView):
        template_name = 'cart/cart.html'
        success_url = 'cart.html'
 
        def get_context_data(self, **kwargs):
            context = super(MainCartView, self).get_context_data(**kwargs)
            context['cart'] = Cart(self.request)
            return context

def get_context_data(self, **kwargs):
            context = super(MainCartView, self).get_context_data(**kwargs)
            context['cart'] = Cart(self.request)
            return context