public IActionResult Add(HD_XUAT newBillOut)
 {
     if (ModelState.IsValid)
     {
         newBillOut.TongCong = newBillOut.PhiVanCHuyen + newBillOut.TongTien;
         _database.HD_XUAT.Add(newBillOut);
         _database.SaveChanges();
         return(RedirectToAction("Index", "HoaDonXuatt"));
     }
     else
     {
         return(View(newBillOut));
     }
 }
        public IActionResult Edit(int id)
        {
            var     billOut          = _database.HD_XUAT.FirstOrDefault(ch => ch.MaHDX == id);
            HD_XUAT billoutViewModel = new HD_XUAT()
            {
                MaHDX = billOut.MaHDX,
                MaKH  = billOut.MaKH,

                Ngay         = billOut.Ngay,
                TongTien     = billOut.TongTien,
                PhiVanCHuyen = billOut.PhiVanCHuyen,
                TongCong     = billOut.TongCong,
            };

            return(View(billoutViewModel));
        }