Djang中的“Decimal类型对象不可序列化为JSON”错误

Question

我遵循'Django2的例子'的书，以创建一个电子商务网站在Django。但是，当我试图将订单id保存到请求会话在下面的行中。你知道吗

    request.session['order_id'] = order.id

    def order_create(request):
cart = Cart(request)
if request.method == 'POST':
    form = OrderCreateForm(request.POST)
    if form.is_valid():
        order = form.save()
        for item in cart:
            OrderItem.objects.create(
                order=order, product=item['product'], price=item['price'], quantity=item['quantity'])

        # cart.clear()
        order_created.delay(order.id)

        request.session['order_id'] = order.id

        return redirect(reverse('payment:process'))
else:
    form = OrderCreateForm()

return render(request, 'orders/order/create.html', {'cart': cart, 'form': form})