public ActionResult ById(int id)
        {
            Article article = articles.Find(id);

            ArticleDetail articleDetail = new ArticleDetail();
            articleDetail.InjectFrom(article);

            return View("Index", articleDetail);
        }
        public ActionResult ByCategory(Category category)
        {
            Article article = articles.First(a => a.Category == category);

            ArticleDetail articleDetail = new ArticleDetail();
            articleDetail.InjectFrom(article);

            return View("Index", articleDetail);
        }