Tapestry 5.3.8 + Jetty + Hibernate 4.3.5 + XAMPP 1.8.3 - IdClass 使用（派生）实体，为啥在尝试合并时它们会分离？
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【中文标题】Tapestry 5.3.8 + Jetty + Hibernate 4.3.5 + XAMPP 1.8.3 - IdClass 使用（派生）实体，为啥在尝试合并时它们会分离？【英文标题】：Tapestry 5.3.8 + Jetty + Hibernate 4.3.5 + XAMPP 1.8.3 - IdClass uses (derived) entities, why are they detached when trying to merge?Tapestry 5.3.8 + Jetty + Hibernate 4.3.5 + XAMPP 1.8.3 - IdClass 使用（派生）实体，为什么在尝试合并时它们会分离？ 【发布时间】：2015-02-12 09:15:13 【问题描述】：使用问题中的组合，我有以下实体：
一些任务：
@Entity
public class Task
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private long id;
一些工人：
@Entity
public class Worker
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
@NonVisual
private long id;
还有一些关于任务的状态：
@Entity
@IdClass(TaskStatusId.class)
public class TaskStatus
@Id
@ManyToOne
private Worker worker
@Id
@ManyToOne
private Task task;
注意：我在 TaskStatus 和其他两个实体之间只有单向关系。 Task 和 Worker 都不包含 List。
现在我有一些用于 Tasks 和 Workers 的数据库条目，还有一些用于 stati 的条目。这些是在应用程序启动时创建并保留的测试对象。这一切都很好。
现在我有一个 Tapestry 页面，它可以找到一个任务和一个工作人员并将它们存储在页面属性中。
SomePage.java：
@Property
@Persist
private Task someTask;
@Property
@Persist
private Worker someWorker;
SomePage.tml:
<t:someComponent selectedTask="someTask" selectedWorker="someWorker"/>
页面中的组件接收 Task 和 Worker 作为参数，并使用我的 DAO 层来查找 TaskStatus，这也可以。
SomeComponent.java:
@Parameter(required=true)
@Property
Task selectedTask;
@Parameter(required=true)
@Property
Worker selectedWorker;
@Property
@Persist
TaskStatus someStatus;
void setupRender()
if (selectedTask != null && user != null)
if (someStatus == null || someStatus.getTask() != selectedTask)
someStatus = taskStatusDAO.findByWorkerAndTask(selectedWorker, selectedTask);
public void onActionFromUpdateStatus()
someStatus = taskStatusDAO.update(someStatus);
最后，我在组件中有一个 Actionlink，它执行以下操作：
更新 TaskStatus 对象中的日期字段 尝试使用我的 DAO 层将更改保存到对象，更具体的是我的合并方法：界面：
@CommitAfter
public T update(T entity);
实施：
public T update(T entity)
return em.merge(entity);
当我尝试合并 TaskStatus 对象时，出现异常：
org.hibernate.PersistentObjectException:
detached entity passed to persist: some.package.Task
堆栈跟踪：
[ERROR] TapestryModule.RequestExceptionHandler Processing of request failed with uncaught exception: org.hibernate.PersistentObjectException: detached entity passed to persist: some.package.entities.Task
org.apache.tapestry5.ioc.internal.OperationException: org.hibernate.PersistentObjectException: detached entity passed to persist: some.package.entities.Task [at classpath:some/package/components/affected/someComponent.tml, line 21]
at org.apache.tapestry5.ioc.internal.OperationTrackerImpl.logAndRethrow(OperationTrackerImpl.java:121)
at org.apache.tapestry5.ioc.internal.OperationTrackerImpl.invoke(OperationTrackerImpl.java:88)
at org.apache.tapestry5.ioc.internal.PerThreadOperationTracker.invoke(PerThreadOperationTracker.java:87)
at org.apache.tapestry5.ioc.internal.RegistryImpl.invoke(RegistryImpl.java:1124)
at org.apache.tapestry5.internal.structure.ComponentPageElementResourcesImpl.invoke(ComponentPageElementResourcesImpl.java:146)
at org.apache.tapestry5.internal.structure.ComponentPageElementImpl.triggerContextEvent(ComponentPageElementImpl.java:1058)
at org.apache.tapestry5.internal.services.AjaxComponentEventRequestHandler.handle(AjaxComponentEventRequestHandler.java:110)
at org.apache.tapestry5.internal.services.ajax.AjaxFormUpdateFilter.handle(AjaxFormUpdateFilter.java:56)
at $ComponentEventRequestHandler_20d7f9a2019d1.handle(Unknown Source)
at $ComponentEventRequestHandler_20d7f9a2019c9.handle(Unknown Source)
at org.apache.tapestry5.internal.services.AjaxFilter.handle(AjaxFilter.java:42)
at $ComponentEventRequestHandler_20d7f9a2019cb.handle(Unknown Source)
at org.apache.tapestry5.upload.internal.services.UploadExceptionFilter.handle(UploadExceptionFilter.java:75)
at $ComponentEventRequestHandler_20d7f9a2019cb.handle(Unknown Source)
at org.apache.tapestry5.services.TapestryModule$41.handle(TapestryModule.java:2475)
at $ComponentEventRequestHandler_20d7f9a2019cb.handle(Unknown Source)
at $ComponentEventRequestHandler_20d7f9a2018ce.handle(Unknown Source)
at org.apache.tapestry5.internal.services.ComponentRequestHandlerTerminator.handleComponentEvent(ComponentRequestHandlerTerminator.java:43)
at some.package.services.PageProtectionFilter.handleComponentEvent(PageProtectionFilter.java:94)
at $ComponentRequestFilter_20d7f9a2018cd.handleComponentEvent(Unknown Source)
at $ComponentRequestHandler_20d7f9a2018d0.handleComponentEvent(Unknown Source)
at org.apache.tapestry5.services.InitializeActivePageName.handleComponentEvent(InitializeActivePageName.java:39)
at $ComponentRequestHandler_20d7f9a2018d0.handleComponentEvent(Unknown Source)
at $ComponentRequestHandler_20d7f9a20189c.handleComponentEvent(Unknown Source)
at org.apache.tapestry5.internal.services.ComponentEventDispatcher.dispatch(ComponentEventDispatcher.java:46)
at $Dispatcher_20d7f9a20189f.dispatch(Unknown Source)
at $Dispatcher_20d7f9a201898.dispatch(Unknown Source)
at org.apache.tapestry5.services.TapestryModule$RequestHandlerTerminator.service(TapestryModule.java:302)
at some.package.services.AppModule$1.service(AppModule.java:175)
at $RequestFilter_20d7f9a201897.service(Unknown Source)
at $RequestHandler_20d7f9a201899.service(Unknown Source)
at org.apache.tapestry5.internal.services.RequestErrorFilter.service(RequestErrorFilter.java:26)
at $RequestHandler_20d7f9a201899.service(Unknown Source)
at org.apache.tapestry5.services.TapestryModule$3.service(TapestryModule.java:902)
at $RequestHandler_20d7f9a201899.service(Unknown Source)
at org.apache.tapestry5.services.TapestryModule$2.service(TapestryModule.java:892)
at $RequestHandler_20d7f9a201899.service(Unknown Source)
at org.apache.tapestry5.internal.services.StaticFilesFilter.service(StaticFilesFilter.java:90)
at $RequestHandler_20d7f9a201899.service(Unknown Source)
at org.apache.tapestry5.internal.services.CheckForUpdatesFilter$2.invoke(CheckForUpdatesFilter.java:105)
at org.apache.tapestry5.internal.services.CheckForUpdatesFilter$2.invoke(CheckForUpdatesFilter.java:96)
at org.apache.tapestry5.ioc.internal.util.ConcurrentBarrier.withRead(ConcurrentBarrier.java:85)
at org.apache.tapestry5.internal.services.CheckForUpdatesFilter.service(CheckForUpdatesFilter.java:119)
at $RequestHandler_20d7f9a201899.service(Unknown Source)
at $RequestHandler_20d7f9a20188d.service(Unknown Source)
at org.apache.tapestry5.services.TapestryModule$HttpServletRequestHandlerTerminator.service(TapestryModule.java:253)
at org.got5.tapestry5.jquery.services.AjaxUploadServletRequestFilter.service(AjaxUploadServletRequestFilter.java:27)
at $HttpServletRequestHandler_20d7f9a20188f.service(Unknown Source)
at org.apache.tapestry5.internal.gzip.GZipFilter.service(GZipFilter.java:53)
at $HttpServletRequestHandler_20d7f9a20188f.service(Unknown Source)
at org.apache.tapestry5.upload.internal.services.MultipartServletRequestFilter.service(MultipartServletRequestFilter.java:44)
at $HttpServletRequestHandler_20d7f9a20188f.service(Unknown Source)
at org.apache.tapestry5.internal.services.IgnoredPathsFilter.service(IgnoredPathsFilter.java:62)
at $HttpServletRequestFilter_20d7f9a20188a.service(Unknown Source)
at $HttpServletRequestHandler_20d7f9a20188f.service(Unknown Source)
at org.apache.tapestry5.services.TapestryModule$1.service(TapestryModule.java:852)
at $HttpServletRequestHandler_20d7f9a20188f.service(Unknown Source)
at $HttpServletRequestHandler_20d7f9a201888.service(Unknown Source)
at org.apache.tapestry5.TapestryFilter.doFilter(TapestryFilter.java:171)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1148)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:387)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:417)
at org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:230)
at org.mortbay.jetty.handler.HandlerCollection.handle(HandlerCollection.java:114)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:324)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:535)
at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:880)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:747)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:218)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:409)
at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:520)
Caused by: org.apache.tapestry5.runtime.ComponentEventException: org.hibernate.PersistentObjectException: detached entity passed to persist: some.package.entities.Task [at classpath:some/package/components/affected/someComponent.tml, line 21]
at org.apache.tapestry5.internal.structure.ComponentPageElementImpl.processEventTriggering(ComponentPageElementImpl.java:1141)
at org.apache.tapestry5.internal.structure.ComponentPageElementImpl.access$3100(ComponentPageElementImpl.java:61)
at org.apache.tapestry5.internal.structure.ComponentPageElementImpl$5.invoke(ComponentPageElementImpl.java:1062)
at org.apache.tapestry5.internal.structure.ComponentPageElementImpl$5.invoke(ComponentPageElementImpl.java:1060)
at org.apache.tapestry5.ioc.internal.OperationTrackerImpl.invoke(OperationTrackerImpl.java:74)
... 74 more
Caused by: javax.persistence.PersistenceException: org.hibernate.PersistentObjectException: detached entity passed to persist: some.package.entities.Task
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1763)
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1677)
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1683)
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.merge(AbstractEntityManagerImpl.java:1206)
at $EntityManager_14b7d075216.merge($EntityManager_14b7d075216.java)
at some.package.dao.AbstractDAOImpl.update(AbstractDAOImpl.java:34)
at $TaskStatusDAO_20d7f9a2019e4.update(Unknown Source)
at $TaskStatusDAO_20d7f9a2019e5.advised$update_20d7f9a2019eb(Unknown Source)
at $TaskStatusDAO_20d7f9a2019e5$Invocation_update_20d7f9a2019ea.proceedToAdvisedMethod(Unknown Source)
at org.apache.tapestry5.internal.plastic.AbstractMethodInvocation.proceed(AbstractMethodInvocation.java:84)
at org.apache.tapestry5.internal.jpa.CommitAfterMethodAdvice.advise(CommitAfterMethodAdvice.java:48)
at org.apache.tapestry5.internal.plastic.AbstractMethodInvocation.proceed(AbstractMethodInvocation.java:86)
at $TaskStatusDAO_20d7f9a2019e5.update(Unknown Source)
at $TaskStatusDAO_20d7f9a201879.update(Unknown Source)
at some.package.components.affected.someComponent.onActionFromSendConfirmation(someComponent.java:59)
at some.package.components.affected.someComponent.dispatchComponentEvent(someComponent.java)
at org.apache.tapestry5.internal.structure.ComponentPageElementImpl.dispatchEvent(ComponentPageElementImpl.java:932)
at org.apache.tapestry5.internal.structure.ComponentPageElementImpl.processEventTriggering(ComponentPageElementImpl.java:1117)
... 78 more
Caused by: org.hibernate.PersistentObjectException: detached entity passed to persist: some.package.entities.Task
at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:139)
at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:75)
at org.hibernate.tuple.entity.AbstractEntityTuplizer$IncrediblySillyJpaMapsIdMappedIdentifierValueMarshaller.getIdentifier(AbstractEntityTuplizer.java:494)
at org.hibernate.tuple.entity.AbstractEntityTuplizer.getIdentifier(AbstractEntityTuplizer.java:342)
at org.hibernate.persister.entity.AbstractEntityPersister.getIdentifier(AbstractEntityPersister.java:4746)
at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:129)
at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:76)
at org.hibernate.internal.SessionImpl.fireMerge(SessionImpl.java:876)
at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:858)
at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:863)
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.merge(AbstractEntityManagerImpl.java:1196)
... 92 more
如果我创建一个单独的标识符并且不使用复合 ID，则更新/合并 TaskStatus 可以工作。但如果没有必要，我宁愿不改变它。
要使用派生 (?) 实体来使用复合 id，我需要做什么？
【问题讨论】：
【参考方案1】：如果为每个 HTTP 请求创建了一个新的 Hibernate 会话（这很可能发生），那么您面临的问题是由于您系统地在会话中保存数据库中的数据（属性 'someTask' , 'someWorker' 和 'someStatus')。
发生了什么：
第一个 HTTP 请求：渲染页面
创建了一个新的 Hibernate 会话。 在此 HTTP 请求结束时，您的属性值将存储在会话中，同时您的 Hibernate 会话已关闭。第二个 HTTP 请求：来自更新状态的操作
创建了一个新的 Hibernate 会话。 Tapestry 从用户会话中获取属性值，并将它们重新注入到组件的 java 属性中。但是这些值不会连接到您的新 Hibernate 会话，这会导致您在使用其中之一调用 DAO 时遇到错误。要解决这个问题，我认为你应该：
避免使用持久属性（我认为您在这里不需要这样做？）， 在每个 HTTP 请求开始时调用 DAO 的“读取”方法，以获取连接到 Hibernate 会话的新 Hibernate 实体， 然后在这个实体上做你的事情。【讨论】：
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