def add_cart(request, pk):
    print(request.session['cart'])
    bag = get_object_or_404(models.Bag, id=pk)
    if request.method == 'POST':
        if request.session['cart'] == None:
            request.session['cart'] = []
        request.session['cart'].append(pk)
        print(request.session['cart'])



    return render(request, 'products/detail.html', {'bag': bag})