public Boolean update_tonkho() { //get orginal NhapHangController Or_ctr = new NhapHangController(); NhapHang Or_nh = Or_ctr.get_by_id(this.id); List<ChiTiet_NhapHang> Or_list; if (Or_nh != null) Or_list = Or_nh.ds_chitiet_nhaphang; else Or_list = new List<ChiTiet_NhapHang>(); //get current List<ChiTiet_NhapHang> Cur_list = this.ds_chitiet_nhaphang; //get Added CTNH Items List<ChiTiet_NhapHang> Added_list = Cur_list.Where(cur => Or_list.Where(or => or.sanpham_chitiet.id == cur.sanpham_chitiet.id).FirstOrDefault() == null).ToList(); //do action try { foreach (ChiTiet_NhapHang ctnh in Added_list) { ctnh.sanpham_chitiet.update_tonkho(ctnh.sanpham_chitiet.tonkho + ctnh.soluong, this.ngay); } } catch (Exception) { return false; } return true; }