order_products_price

    def save(self, *args, **kwargs):
        '''
        в дополнение ко стандартной процедуре сохранения
        обновить цену заказа в соответствии
         с ценами на продукты и добавки
        '''
        products_price_expression = ExpressionWrapper(F('amount') * F('price'),
                                                      output_field=models.DecimalField(max_digits=10,
                                                                                       decimal_places=2))

        products = self.products.annotate(
            additions_price=models.Sum('additions__price'),
            product_price=products_price_expression)
        order_price = products.aggregate(order_price=models.Sum(F('additions_price') + F('product_price')))
        print(order_price['order_price'])
        price = 0
        for product in products:
            print(product.additions_price, product.product_price)
            product_price = (product.additions_price or 0) + product.product_price
            price += product_price
        self.price = price
        return super().save(*args, **kwargs)