在尝试通过 REST API 更新资源时，我遇到了使用 Spring 和 Hibernate 时遇到的错误。

我用最少的额外属性简化了案例。

基本模型概述

我正在尝试更新名为 Rule 的资源。
Rule 有一个 ThingGroup，它是一组对象的表示。 Rule还有一组Event，代表规则的激活范围。 在应用程序执行期间，运行必须检查该事物组上的某些参数以触发警报。

hibernate 引发的错误

我的问题是，在下面的规则服务中使用 update 方法时，它会失败并出现此错误。

 org.hibernate.PersistentObjectException: detached entity passed to persist: com.smartobjectsecurity.common.domain.rule.Event
at org.springframework.orm.jpa.vendor.HibernateJpaDialect.convertHibernateAccessException(HibernateJpaDialect.java:276)
at org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:221)
at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.translateExceptionIfPossible(AbstractEntityManagerFactoryBean.java:417)
at org.springframework.dao.support.ChainedPersistenceExceptionTranslator.translateExceptionIfPossible(ChainedPersistenceExceptionTranslator.java:59)
at org.springframework.dao.support.DataAccessUtils.translateIfNecessary(DataAccessUtils.java:213)
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:147)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.data.jpa.repository.support.LockModeRepositoryPostProcessor$LockModePopulatingMethodIntercceptor.invoke(LockModeRepositoryPostProcessor.java:105)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:207)
at com.sun.proxy.$Proxy117.findOne(Unknown Source)
at com.smartobjectsecurity.common.service.thing.ThingGroupServiceImpl.find(ThingGroupServiceImpl.java:62)
at com.smartobjectsecurity.common.service.thing.ThingGroupServiceImpl.find(ThingGroupServiceImpl.java:1)
at com.smartobjectsecurity.common.service.GenericServiceImpl.find(GenericServiceImpl.java:1)
at com.smartobjectsecurity.common.service.GenericServiceImpl$$FastClassBySpringCGLIB$$daaa7267.invoke(<generated>)
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:717)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:281)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:653)
at com.smartobjectsecurity.common.service.thing.ThingGroupServiceImpl$$EnhancerBySpringCGLIB$$aa452fd7.find(<generated>)
at com.smartobjectsecurity.common.service.rule.RuleServiceImpl.update(RuleServiceImpl.java:219)

RuleService 的更新方法

下面是 ruleService update 方法。
首先，我需要使用 reactGroup 服务更新关联的 react 组。

@Transactional
public Rule update(final Rule rule, User user) throws UnknownEntityException, MyBadRequestException {
     final Long id = rule.getId();
     Rule found = null;
     try {
          found = find(id, user);
          found.setEvents(rule.getEvents());
          thingGroupService.find(rule.getThingGroup().getId(), user);
          found.setThingGroup(rule.getThingGroup());
          found = dao.saveAndFlush(found);

     } catch (final UnknownEntityException e) {
          final UnknownEntityException ex = new UnknownEntityException("UnknownEntity/ResourceException.rule", "update_unknown_rule");
          ex.setParameters(new Object[] { id });
          throw ex;
     }

     return found;
}

ThingGroupService 的查找方法

 @Override
 @Transactional(rollbackFor = UnknownEntityException.class )
 public ThingGroup find(final Long id, User user) throws UnknownEntityException {
      logger.debug("-> find, id = " + id);
      final ThingGroup found = getDao().findOne(buildSpecificationForIdAndUser(id, user));
      if (found == null) {
           final UnknownEntityException ex = new UnknownEntityException("UnknownEntity/ResourceException.thingGroup", "unknown_thingGroup");
           ex.setParameters(new Object[] { id });
           throw ex;
      }
      logger.debug("<- find : " + found);
      return found;
 }

这里要求的是 buildSpecificationForIdAndUser 和 buildSpecificationForUser 方法。
它们用于根据用户的权限构建搜索限制。

 @Transactional
protected Specification<ENTITY> buildSpecificationForIdAndUser(final ID id,final User user){
    return new Specification<ENTITY>() {
        @Override
        public Predicate toPredicate(Root<ENTITY> root, CriteriaQuery<?> query, CriteriaBuilder builder) {
            Expression<Long> entityId = root.get("id");


            Predicate userPredicate = buildSpecificationForUser(user).toPredicate(root, query, builder);

            return builder.and(
                builder.equal(entityId, id),
                userPredicate
            );
        }
    };
}

 @Override
@Transactional
protected Specification<ThingGroup> buildSpecificationForUser(final User user) {
    return new Specification<ThingGroup>() {
        @Override
        public Predicate toPredicate(Root<ThingGroup> root, CriteriaQuery<?> query, CriteriaBuilder builder) {
            Expression<Collection<User>> managersOfThingGroup = root.get("managers");
            Expression<Company> thingGroupCompany = root.get("company");

            Predicate isManager = builder.isMember(user, managersOfThingGroup);
            Predicate isSameCompany = builder.equal(thingGroupCompany,user.getCompany());

            return builder.and(isSameCompany,isManager);

        }
    };
}

错误在哪里

当尝试运行 thingGroupService.find(rule.getThingGroup().getId(), user); 时，Hibernate 突然抛出有关 Event 实体的异常(传递给持久化的分离实体)。 我真的不知道这里出了什么问题。
几天来，我一直在搜索各种论坛，但没有找到问题的原因。

问题

为什么在与事件无关的 ThingGroup 资源上运行查找后，Event 实体突然与 session 分离？

最佳答案

您不必为已附加的实体调用 saveAndFlush，因此应将服务方法更改为:

found = find(id, user);
thingGroupService.find(rule.getThingGroup().getId(), user);
found.setThingGroup(rule.getThingGroup());
found.setEvents(rule.getEvents());

found 实体已经与当前Session 相关联，因此dirty checking mechanism 检测到所有更改和 child entity state transitions如果启用级联，则传播。

https://stackoverflow.com/questions/31963702/