@RequestMapping(value = "/sach/list", method = RequestMethod.GET)
 public String hienThiDanhMucSach(Model model) {
   List<Sach> sachs = sachService.timTatCaCuonSach();
   List<SachUI> sachUIs = SachMapper.convertToListSachUI(sachs);
   model.addAttribute("sachUIs", sachUIs);
   return WebConstant.views.DANH_MUC_SACH;
 }
  @RequestMapping(value = "/sach/add", method = RequestMethod.POST)
  public String create(SachUI sachUI, Model model) {
    TheLoaiSach theLoaiSach = theLoaiSachService.timTheLoaiSachByTen(sachUI.getTheLoaiUI());
    if (theLoaiSach != null) {
      Sach sach = SachMapper.convertToSach(sachUI, theLoaiSach);
      sachService.saveOrUpdate(sach);
    }

    return "redirect:/sach/list";
  }
 @RequestMapping(value = "/sach/edit", method = RequestMethod.GET)
 public String hienThiSuaSach(
     @RequestParam(value = "maSach", required = true) String maSach, Model model) {
   Sach sachExisting = sachService.timSachByMaSach(maSach);
   if (sachExisting != null) {
     SachUI sachUI = SachMapper.convertToSachUI(sachExisting);
     model.addAttribute("sachUI", sachUI);
     List<TheLoaiSach> tLSs = theLoaiSachService.timDanhMucTheLoaiSach();
     List<TheLoaiSachUI> tLSUIs = TheLoaiSachMapper.convertToListTheLoaiSachUI(tLSs);
     model.addAttribute("theLoaiUIs", tLSUIs);
   }
   model.addAttribute("btnName", "Sửa Thông Tin Sách");
   return WebConstant.views.THEM_SACH;
 }