def get(self, request, *args, **kwargs):
product_slug = kwargs.get('slug')
product = Product.objects.get(slug=product_slug)
cart = Cart(request)
cart.change_product_quantity(product, int(request.GET.get('quantity')))
messages.add_message(request, messages.INFO,
'Количество {} изменено'.format(product.title))
return HttpResponseRedirect('/cart/')
