public IEnumerable <HangHoaViewModel> GetHangHoa(string search = "", int pageIndex = 1, int pageSize = 50)
        {
            if (!string.IsNullOrEmpty(search))
            {
                search = search.ToLower().Trim();
            }
            var data = _context.HangHoa.Where(p => p.TenHh.ToLower().Contains(search))
                       .Skip((pageIndex - 1) * pageSize).Take(pageSize)
                       .Select(p => new HangHoaViewModel
            {
                MaHh   = p.MaHh,
                TenHh  = p.TenHh,
                DonGia = p.DonGia.Value * (1 - p.GiamGia),
                Hinh   = MyTool.GetFullImagePath(HttpContext.Request, "HangHoa", p.Hinh)
            });

            return(data);
        }