public ActionResult Index(string keyword, int page = 1)
        {
            int totalItems = 0;
            var categories = categoryService.GetCategories(page, OnlineStore.Infractructure.Utility.Define.PAGE_SIZE, out totalItems);

            IPagedList <SummaryCategoryViewModel> pageCategories = new StaticPagedList <SummaryCategoryViewModel>(categories, page, OnlineStore.Infractructure.Utility.Define.PAGE_SIZE, totalItems);

            return(View(pageCategories));
        }