public IActionResult AddArticleToCart(int id)
{
string jsonCart = HttpContext.Session.GetString("cart");
Cart cart = (jsonCart == null) ? new Cart() : JsonConvert.DeserializeObject <Cart>(jsonCart);
cart.AddArticleToCart(Article.GetArticleById(id));
HttpContext.Session.SetString("cart", JsonConvert.SerializeObject(cart));
string total = Convert.ToString(cart.Total);
HttpContext.Session.SetString("Total", total);
string nbArticles = Convert.ToString(cart.NbArticles);
HttpContext.Session.SetString("NbArticles", nbArticles);
return(RedirectToRoute(new { controller = "Cart", action = "UserCart" }));
}