public void Edit(int id)
        {
            if (HasPermission(Permission.UpdateArticle))
            {
                PropertyBag["category"] = _category.Find(id);
            }
        }

        public void Edit([DataBind("category")] ArticleCategory category)
        {
            if (HasPermission(Permission.UpdateArticle))
            {
                _category.Validate(category);

                if (_category.HasError)
                {
                    Flash["errors"] = _category.Errors;
                    Flash["category"] = category;

                    RedirectToReferrer();
                }
                else
                {
                    _category.Update(category);

                    Redirect("admin/article", "category", "list");
                }
            }
        }