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我对 Hibernate 还很陌生，并且一直在使用手册和在线论坛，但我对这个问题感到困惑。我正在使用带有 Hibernate 4 和注释的 Spring 3.2。我有一个一对多的父 (PledgeForm) 和子 (PledgeFormGiftLevel) 表。

域/模型：父级

@Entity
@Table(name="PLEDGE_FORMS")
@SuppressWarnings("serial")
public class PledgeForm implements Serializable {

static final Logger log = Logger.getLogger(PledgeForm.class);

@Id
@GeneratedValue(strategy=GenerationType.AUTO, generator="pledge_form_seq")
@SequenceGenerator(name="pledge_form_seq", sequenceName="PLEDGE_FORM_SEQ")
@Column(name="ID", unique=true, nullable=false)
private Integer id;

….

@OneToMany(mappedBy="pledgeForm", fetch=FetchType.EAGER, cascade=CascadeType.ALL)//********1
private List<PledgeFormGiftLevel> pledgeFormGiftLevels = new ArrayList<PledgeFormGiftLevel>();

….

public List<PledgeFormGiftLevel> getPledgeFormGiftLevels() {
   return this.pledgeFormGiftLevels;
}

public void setPledgeFormGiftLevels(List<PledgeFormGiftLevel> pledgeFormGiftLevels) {
   this.pledgeFormGiftLevels = pledgeFormGiftLevels;
}

//I do not think the following method is needed, but I decided to try it just in case
public void addPledgeFormGiftLevels(PledgeFormGiftLevel pledgeFormGiftLevels) {
   pledgeFormGiftLevels.setPledgeForm(this);
   getPledgeFormGiftLevels().add(pledgeFormGiftLevels);
}

孩子

@Entity
@Table(name="PLEDGE_FORM_GIFT_LEVELS")
@SequenceGenerator(name="pledge_form_gift_level_seq", sequenceName="PLEDGE_FORM_GIFT_LEVEL_SEQ")
@SuppressWarnings("serial")
public class PledgeFormGiftLevel implements Serializable {

static final Logger log = Logger.getLogger(PledgeFormGiftLevel.class);

@Id
@GeneratedValue(strategy=GenerationType.AUTO, generator="pledge_form_gift_level_seq")
@Column(name="ID", unique=true, nullable=false)
private Integer id; 

…

@ManyToOne(fetch=FetchType.EAGER)//yes?
@JoinColumn(name="PLEDGE_FORM_ID", referencedColumnName="ID", insertable=true, updatable=true)//yes?
private PledgeForm pledgeForm = new PledgeForm();

…

public PledgeForm getPledgeForm() {
   return pledgeForm;
}
public void setPledgeForm(PledgeForm pledgeForm) {
   this.pledgeForm = pledgeForm;
}

控制器（有一个图形，所以我有代码可以拉入文件）：

@Controller
@SessionAttributes("pledgeForm")
public class PledgeFormController {
   @Autowired
   org.unctv.service.PledgeFormManager Service;

…

@RequestMapping(value = "/saveJdbcPledgeForm", method = RequestMethod.POST, params="save")
public ModelAndView save(
   @ModelAttribute("pledgeForm")
   @Valid PledgeForm pledgeForm, BindingResult result,
   @RequestParam("logoImg") MultipartFile file,
   @RequestParam(value="removeLogoImg", required=false) String removeLogoImg) throws Exception {

      ModelAndView mav = null;
      mav = new ModelAndView("pledgeFormSearch");//Name of the JSP

      if (removeLogoImg != null) {
         pledgeForm.setLogoFilename(null);

         pledgeForm.setLogoImg(null);
         pledgeForm.setLogoContentType(null);
      } else if (file != null && file.getBytes().length > 0) {
         pledgeForm.setLogoFilename(file.getOriginalFilename());
         pledgeForm.setLogoImg(file.getBytes());
         pledgeForm.setLogoContentType(file.getContentType());
      }

      Service.save(pledgeForm);
      mav.addObject("pledgeForm", pledgeForm);//JSP Form's Command Name (pledgeForm); 
      mav.addObject("cmdName", "pledgeForm");
      mav.addObject("actionType", "Save");
      return mav;
}

服务：

@Service("simplePledgeFormManager")
@Transactional(readOnly=true)
public class SimplePledgeFormManager implements PledgeFormManager { 
   @Autowired
   private HibernatePledgeFormDao hibernatePledgeFormDao;


…

@Transactional(readOnly=false)
public void save(PledgeForm pledgeForm) throws Exception {
   hibernatePledgeFormDao.save(pledgeForm);
}

道：

@Repository("PledgeFormDAO")
public class HibernatePledgeFormDao implements PledgeFormDao {

static final Logger log = Logger.getLogger(HibernatePledgeFormDao.class);

   @Autowired
   private SessionFactory sessionFactory;


...

@Override
public void save(PledgeForm pledgeForm) throws Exception {
   sessionFactory.getCurrentSession().saveOrUpdate(pledgeForm);
}

使用上面的代码，可以很好地选择和更新父/子记录。当我显示来自休眠的“跟踪”消息时，更新确实有这个关于孩子的跟踪消息，但是：

[2013-12-06 10:31:24,648] TRACE Persistent instance of: org.unctv.domainmodel.PledgeFormGiftLevel
[2013-12-06 10:31:24,649] TRACE Ignoring persistent instance
[2013-12-06 10:31:24,649] TRACE Object already associated with session: [org.unctv.domainmodel.PledgeFormGiftLevel#1]

如果有子记录，create 总是会给出这个错误：

object references an unsaved transient instance - save the transient instance before flushing: org.unctv.domainmodel.PledgeForm; nested exception is org.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance before flushing: org.unctv.domainmodel.PledgeForm

当我查看休眠日志时，我看到它根据瞬态对象更新父级和子级。然后它尝试刷新并找到孩子的持久副本，因此它回滚所有内容。

[2013-12-06 10:34:13,615] TRACE Automatically flushing session
[2013-12-06 10:34:13,615] TRACE Flushing session
[2013-12-06 10:34:13,615] DEBUG Processing flush-time cascades
[2013-12-06 10:34:13,615] TRACE Processing cascade ACTION_SAVE_UPDATE for: org.unctv.domainmodel.PledgeForm
[2013-12-06 10:34:13,615] TRACE Cascade ACTION_SAVE_UPDATE for collection: org.unctv.domainmodel.PledgeForm.pledgeFormGiftLevels
[2013-12-06 10:34:13,615] TRACE Cascading to save or update: org.unctv.domainmodel.PledgeFormGiftLevel
[2013-12-06 10:34:13,616] TRACE Persistent instance of: org.unctv.domainmodel.PledgeFormGiftLevel
[2013-12-06 10:34:13,616] TRACE Ignoring persistent instance
[2013-12-06 10:34:13,616] TRACE Object already associated with session: [org.unctv.domainmodel.PledgeFormGiftLevel#51]
[2013-12-06 10:34:13,616] TRACE Done cascade ACTION_SAVE_UPDATE for collection: org.unctv.domainmodel.PledgeForm.pledgeFormGiftLevels
[2013-12-06 10:34:13,616] TRACE Done processing cascade ACTION_SAVE_UPDATE for: org.unctv.domainmodel.PledgeForm
[2013-12-06 10:34:13,617] DEBUG Dirty checking collections
[2013-12-06 10:34:13,617] TRACE Flushing entities and processing referenced collections
[2013-12-06 10:34:13,617] DEBUG Collection found: [org.unctv.domainmodel.PledgeForm.pledgeFormGiftLevels#51], was: [<unreferenced>] (initialized)
[2013-12-06 10:34:13,618] DEBUG rolling back
[2013-12-06 10:34:13,618] DEBUG rolled JDBC Connection

Hibernate 文档显示这比我的代码更简单，但我必须添加 fetch & cascade 值。我已经尝试过更改获取和级联值和放置（从 Hibernate 文档开始，然后添加），但是我尝试的其他所有操作仍然会导致创建失败并且通常也会导致更新失败。

我发现的许多论坛帖子都显示了 flush() 或 evict()。我不确定我正在使用的是 Hibernate 4 还是注释（我认为是 @Transactional），但我在我的代码中看不到它的位置。从 Hibernate 跟踪日志中，我可以看到在 saveOrUpdate() 方法中自动进行了刷新。

我还尝试删除表格和序列并重新开始。

任何关于让创建工作的建议都值得赞赏。如果您能指出我错过的特定文档，那也将不胜感激。

谢谢，邦妮

4

1 回答 1

0

我注意到了这一点，equals并且hashcode没有在实体中被覆盖。这些方法用于比较对象以确定它们的相等性。如果不覆盖这些方法，Hibernate 可能无法确定实体的现有实例是否存在。hashcode尝试为和提供实现equals。

如果您使用 Eclipse，请按CTRL++ ,以SHIFT调出用于创建和方法的对话框。选择包含相对不变的值的字段，然后生成方法。SHhashcodeequals

还要确保您正在管理实体的双方，如上述评论中所述：

public ModelAndView save(
   @ModelAttribute("pledgeForm")
   @Valid PledgeForm pledgeForm, BindingResult result,
   @RequestParam("logoImg") MultipartFile file,
   @RequestParam(value="removeLogoImg", required=false) String removeLogoImg) throws Exception {

      ModelAndView mav = null;
      mav = new ModelAndView("pledgeFormSearch");//Name of the JSP

      //Manage both sides of the entity
      List<PledgeFormGiftLevel> levels = pledgeForm.getPledgeFormGiftLevels();

      for(PledgeFormGiftLevel level: levels){
          level.setPledgeForm(pledgeForm);
      }

      if (removeLogoImg != null) {
         pledgeForm.setLogoFilename(null);

         pledgeForm.setLogoImg(null);
         pledgeForm.setLogoContentType(null);
      } else if (file != null && file.getBytes().length > 0) {
         pledgeForm.setLogoFilename(file.getOriginalFilename());
         pledgeForm.setLogoImg(file.getBytes());
         pledgeForm.setLogoContentType(file.getContentType());
      }

      Service.save(pledgeForm);
      mav.addObject("pledgeForm", pledgeForm);//JSP Form's Command Name (pledgeForm); 
      mav.addObject("cmdName", "pledgeForm");
      mav.addObject("actionType", "Save");
      return mav;
}
于 2013-12-06T16:33:19.323 回答