Java SpringMVC+Hibernate自连接给出了类似“加载需要id”的错误

我想使用hibernate自连接的父子逻辑进行设计

办公室模型课

办公服务Impl类 我有一个服务班。这个类与Dao类相同，它是一个接口

@Service
@Transactional(propagation = Propagation.SUPPORTS, readOnly = true)
public class OfficeServiceImpl implements OfficeService {

    @Autowired
    private OfficeDao officeDao;

    @Transactional(propagation = Propagation.REQUIRED, readOnly = false)
    public void addOffice(Office office) {
        officeDao.addOffice(office);
    }

    @Transactional(propagation = Propagation.REQUIRED, readOnly = true)
    public List<Office> getAllOffice() {
        return officeDao.getAllOffice();
    }

    @Transactional(propagation = Propagation.REQUIRED, readOnly = true)
    public Birim getOfficeById(Integer officeId) {
        return officeDao.getOfficeById(officeId);
    }

}

面板办公室jsp查看页面

我想用父值为null保存General Manager。第二条记录后包括总经理助理和从父列表中选择总经理。当我试图保存General Manager父值为null时，加载错误需要加载id。但是当我手动插入数据库时，总经理的父项为空值。它将被保存，但它也将保存总经理助理，但我不希望它手动插入数据库

@Repository
public class OfficeDaoImpl implements OfficeDao {

    @Autowired
    private SessionFactory sessionFactory;

    @Override
    public void addOffice(Office office) {
        Session session = sessionFactory.getCurrentSession();
        session.saveOrUpdate(office);
        session.flush();
    }

    @Override
    public Office getOfficeById(Integer officeId) {
        Session session = sessionFactory.getCurrentSession();
        Office office = (Office) session.get(Office.class, officeId);
        return office;
    }

    @SuppressWarnings("unchecked")
    @Override
    public List<Office> getAllOffices() {
        Session session = sessionFactory.getCurrentSession();
        return session.createQuery("FROM Office").list();
    }

}

@Controller
@RequestMapping(value = "/panel/office")
public class OfficeController {


    @Autowired
    private OfficeService officeService;

    @RequestMapping(value = "/add", method = RequestMethod.GET)
    public ModelAndView addOfficeGET(@RequestParam(required = false) Integer officeId){
        ModelAndView mav = new ModelAndView("panel/panel-offices");

        Office office = null;       

        if (officeId != null) {
            office = officeService.getOfficeById(officeId);
        }

        if (office == null) {
            office = new Office();
        }

        mav.addObject("office", new Office());
        mav.addObject("offices", officeService.getAllOffice());
        return mav;
    }

    @RequestMapping(value = "/add", method = RequestMethod.POST)
    public ModelAndView addOfficePOST(@Valid @ModelAttribute("office") Office office, BindingResult result){
        ModelAndView mav1 = new ModelAndView();
        ModelAndView mav2 = new ModelAndView("panel/panel-offices");
        mav1.setViewName("redirect:/panel/office/add");

        Office parent = null;
        parent= officeService.getOfficeById(office.getParent().getOfficeId());
        office.setParent(parent);

        if (result.hasErrors()) { 
             return mav2;
        }

        if (office.getOfficeId() != null) {
            officeService.officeGuncelle(office);
        } else {
            officeService.OfficeEkle(office);
        }

        return mav1;

    }

@Service
@Transactional(propagation = Propagation.SUPPORTS, readOnly = true)
public class OfficeServiceImpl implements OfficeService {

    @Autowired
    private OfficeDao officeDao;

    @Transactional(propagation = Propagation.REQUIRED, readOnly = false)
    public void addOffice(Office office) {
        officeDao.addOffice(office);
    }

    @Transactional(propagation = Propagation.REQUIRED, readOnly = true)
    public List<Office> getAllOffice() {
        return officeDao.getAllOffice();
    }

    @Transactional(propagation = Propagation.REQUIRED, readOnly = true)
    public Birim getOfficeById(Integer officeId) {
        return officeDao.getOfficeById(officeId);
    }

}

<div class="form-group">
                <label for="parent">Parent Office Name:</label>
                <form:select path="parent.officeId" class="form-control chosen-full-select">
                    <form:option value="">--Select--</form:option>
                        <c:forEach items="${offices}" var="office">
                            <form:option value="${office.officeId}">${office.officeName}</form:option>
                        </c:forEach>
                </form:select>
            </div>