小贝子编程

如何使用 spring-boot 和 JPA 持久化包含另一个未持久化实体的多个相同实例的新实体?



概述：

我正在构建一个 spring-boot 应用程序，该应用程序部分地从外部 REST 服务中检索一些实体，并将其与数据库中本地保存的实体的先前版本进行比较。

我正在EntityManager注入@PersistenceContext，并使用它来处理数据库，因为有许多实体类型，并且模块最初不知道该类型。我可以从工厂获得JpaRepository，但不同实体类型的数量可能会增长，如果可能的话，我宁愿不依赖它。

问题：

当模块检索它不在数据库中保存的实体时，它会执行一些业务逻辑，然后尝试保留新实体。

Person类是所讨论的实体之一，包含三个类型为Site的字段，它们通常包含相同的对象。

当我尝试在多个字段中保留具有相同Site对象的新Person时，CascadeType.PERSIST，我得到一个EntityExistsException(请参阅堆栈跟踪 (1((。

当我从Site字段中删除CascadeType.PERSIST，并尝试保留在多个字段中具有相同Site对象的新Person时，我得到一个TransientPropertyValueException(请参阅堆栈跟踪(2((。

我想我理解这两种异常发生的原因：

  • 在第一种情况下，这是因为在第一个站点字段级联持久化后，无法为第二个字段重新持久化。

  • 我认为第二种情况是因为@Transactional注释试图刷新事务而不保留站点实例。

我尝试删除@Transactional注释并自己开始和提交 EntityTransaction，但我得到了一个IllegalStateException(参见堆栈跟踪 (3((，尽管我认为这是意料之中的，因为 spring 应该处理事务本身。

我已经查看了类似问题的答案(例如这个，这个(，但都建议更改CascadeType的一些变体。

在另一个问题中，有人建议确保equals()方法正确评估有问题的实体，所以我签入了调试器，((Person)newEntity).currentSite.equals(((Person)newEntity).homeSite)评估结果为 true。

如何跨多个字段一致地持久化/合并具有相同对象的实体？

编辑：我也尝试了级联类型的各种组合与fetch = FetchType.EAGER，但这不会在它们各自的例外中产生任何变化。

编辑2：我尝试使用JpaRepository而不是使用EntityManager，并根据我使用的级联类型有效地获得相同的异常集。

如果我使用PERSIST但没有MERGE，我会得到一个EntityNotFoundException

(参见 stacktrace (4((，如果我同时使用PERSIST和MERGE，我会得到一个 InvalidDataAccessApiUsageException'(参见 stacktrace (5((。

人：

@EqualsAndHashCode(callSuper = true)
@javax.persistence.Entity
@XmlDiscriminatorValue("person")
@XmlRootElement(name = "person")
@XmlAccessorType(XmlAccessType.FIELD)
@XmlSeeAlso({Subscriber.class})
public class Person extends MobileResource implements Serializable {
private static final Logger LOG = LogManager.getLogger(Person.class);
private String firstName;
private String surname;
public Person() {
super();
}
public Person(Long id) {
super(id);
}
public Person(Person that) {
super(that);
this.firstName = that.firstName;
this.surname = that.surname;
}
// getters && setters
}

移动资源：

@EqualsAndHashCode(callSuper = true)
@Entity
@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
@XmlRootElement(name = "resource")
@XmlDiscriminatorNode("@type")
@XmlAccessorType(XmlAccessType.FIELD)
@XmlSeeAlso({Vehicle.class, Person.class})
public abstract class MobileResource extends Resource implements Serializable {
private static final Logger LOG = LogManager.getLogger(MobileResource.class);
@ManyToOne(cascade = CascadeType.ALL)
private MobileResourceStatus status;
private Long                 incidentId;
@ManyToOne(fetch = FetchType.LAZY, cascade = {CascadeType.PERSIST, CascadeType.REMOVE, CascadeType.DETACH})
private Site                 homeSite;
@ManyToOne(fetch = FetchType.LAZY, cascade = {CascadeType.PERSIST, CascadeType.REMOVE, CascadeType.DETACH})
private Site                 currentSite;
@ManyToOne(fetch = FetchType.LAZY, cascade = {CascadeType.PERSIST, CascadeType.REMOVE, CascadeType.DETACH})
private Site                 relocationSite;
public MobileResource() {
super();
}
public MobileResource(Long id) {
super(id);
}
public MobileResource(MobileResource that) {
super(that);
this.status = that.status;
this.incidentId = that.incidentId;
this.homeSite = that.homeSite;
this.currentSite = that.currentSite;
this.relocationSite = that.relocationSite;
}
// getters && setters
}

网站：

@EqualsAndHashCode(callSuper = true)
@javax.persistence.Entity
public class Site extends Resource implements Serializable {
private static final Logger LOG = LogManager.getLogger(Site.class);
private String location;
public Site() {
super();
}
public Site(Long id) {
super(id);
}
public Site(Site that) {
super(that);
this.location = that.location;
}
}

资源：

@EqualsAndHashCode
@MappedSuperclass
@XmlRootElement
@XmlSeeAlso({MobileResource.class})
public abstract class Resource implements Entity, Serializable {
private static final Logger LOG = LogManager.getLogger(Resource.class);
@Id
private Long            id;
private String          callSign;
@XmlPath(".")
private LatLon          latLon;
private Long            brigadeId;
private Long            batchId;
@ManyToMany(cascade = CascadeType.ALL)
private List<Attribute> attributes;
@ManyToOne(fetch = FetchType.LAZY, cascade = {CascadeType.PERSIST, CascadeType.REMOVE, CascadeType.DETACH})
private ResourceType    type;
public Resource() {
}
public Resource(Long id) {
this.id = id;
}
public Resource(Resource that) {
this.id = that.id;
this.callSign = that.callSign;
this.latLon = that.latLon;
this.attributes = that.attributes;
this.batchId = that.batchId;
this.brigadeId = that.brigadeId;
this.type = that.type;
}
// getters && setters
}

DefaultEntityMessageHandler：

@Component
public class DefaultEntityMessageHandler implements EntityMessageHandler {

@PersistenceContext
private EntityManager entityManager;
@Override
@Transactional
public void handleEntityMessage(EntityMessageData data, Message message) {
// business logic
if (newEntity != null) {
if (oldEntity != null)
entityManager.merge(newEntity);
else
entityManager.persist(newEntity);
}
}
}

堆栈跟踪 (1(：

2018-06-06 12:05:15,975 ERROR ActiveMQMessageConsumer - ID:cpt-9225-1528283097161-1:1:1:1 Exception while processing message: ID:cpt-8919-1528281875592-1:1:1:1:4 
javax.persistence.EntityExistsException: A different object with the same identifier value was already associated with the session : [my.class.path.entity.resource.site.Site#738]
at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:118)
at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:157)
at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:164)
at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:813)
at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:773)
at org.hibernate.jpa.event.internal.core.JpaPersistEventListener$1.cascade(JpaPersistEventListener.java:80)
at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:467)
at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:392)
at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:193)
at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:126)
at org.hibernate.event.internal.AbstractSaveEventListener.cascadeBeforeSave(AbstractSaveEventListener.java:414)
at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:252)
at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:182)
at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:125)
at org.hibernate.jpa.event.internal.core.JpaPersistEventListener.saveWithGeneratedId(JpaPersistEventListener.java:67)
at org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:189)
at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:132)
...

更改移动资源中的级联类型：

@ManyToOne(fetch = FetchType.LAZY, cascade = {CascadeType.REMOVE, CascadeType.DETACH})
private Site                 homeSite;
@ManyToOne(fetch = FetchType.LAZY, cascade = {CascadeType.REMOVE, CascadeType.DETACH})
private Site                 currentSite;
@ManyToOne(fetch = FetchType.LAZY, cascade = {CascadeType.REMOVE, CascadeType.DETACH})

堆栈跟踪 (2(：

2018-06-06 12:19:24,084 ERROR ExceptionMapperStandardImpl - HHH000346: Error during managed flush [org.hibernate.TransientPropertyValueException: object references an unsaved transient instance - save the transient instance before flushing : my.class.path.entity.resource.mobile_resource.person.Person.currentSite -> my.class.path.entity.resource.site.Site]
2018-06-06 12:19:24,093 ERROR ActiveMQMessageConsumer - ID:cpt-9436-1528283955454-1:1:1:1 Exception while processing message: ID:cpt-8919-1528281875592-1:1:1:1:8
org.springframework.dao.InvalidDataAccessApiUsageException: org.hibernate.TransientPropertyValueException: object references an unsaved transient instance - save the transient instance before flushing : my.class.path.entity.resource.mobile_resource.person.Person.currentSite -> my.class.path.entity.resource.site.Site; nested exception is java.lang.IllegalStateException: org.hibernate.TransientPropertyValueException: object references an unsaved transient instance - save the transient instance before flushing : my.class.path.entity.resource.mobile_resource.person.Person.currentSite -> my.class.path.entity.resource.site.Site
at org.springframework.orm.jpa.EntityManagerFactoryUtils.convertJpaAccessExceptionIfPossible(EntityManagerFactoryUtils.java:365)
at org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:227)
at org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:540)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:746)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:714)
...

堆栈跟踪 (3(：

2018-06-06 13:29:35,594 ERROR ActiveMQMessageConsumer - ID:cpt-9864-1528288166188-1:1:1:1 Exception while processing message: ID:cpt-8919-1528281875592-1:1:1:1:9
java.lang.IllegalStateException: Not allowed to create transaction on shared EntityManager - use Spring transactions or EJB CMT instead
at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:254)
at com.sun.proxy.$Proxy114.getTransaction(Unknown Source)
at my.class.path.entity_controller.DefaultEntityMessageHandler.handleEntityMessage(DefaultEntityMessageHandler.java:60)
at my.class.path.entity_listener.listeners.IdExtractorMessageListener.onMessage(IdExtractorMessageListener.java:41)
...

堆栈跟踪 (4(

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2018-06-06 15:26:36,143 ERROR SpringApplication - Application run failed
java.lang.IllegalStateException: Failed to execute CommandLineRunner
at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:793)
at org.springframework.boot.SpringApplication.callRunners(SpringApplication.java:774)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:335)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1246)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1234)
at my.class.path.OfficerSubscription.main(OfficerSubscription.java:44)
Caused by: org.springframework.orm.jpa.JpaObjectRetrievalFailureException: Unable to find my.class.path.entity.resource.site.Site with id 738; nested exception is javax.persistence.EntityNotFoundException: Unable to find my.class.path.entity.resource.site.Site with id 738
at org.springframework.orm.jpa.EntityManagerFactoryUtils.convertJpaAccessExceptionIfPossible(EntityManagerFactoryUtils.java:373)
at org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:227)
at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.translateExceptionIfPossible(AbstractEntityManagerFactoryBean.java:507)
at org.springframework.dao.support.ChainedPersistenceExceptionTranslator.translateExceptionIfPossible(ChainedPersistenceExceptionTranslator.java:61)
at org.springframework.dao.support.DataAccessUtils.translateIfNecessary(DataAccessUtils.java:242)
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:153)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
...

堆栈跟踪 (5(

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2018-06-06 15:31:54,840 ERROR SpringApplication - Application run failed
java.lang.IllegalStateException: Failed to execute CommandLineRunner
at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:793)
at org.springframework.boot.SpringApplication.callRunners(SpringApplication.java:774)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:335)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1246)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1234)
at my.class.path.OfficerSubscription.main(OfficerSubscription.java:44)
Caused by: org.springframework.dao.InvalidDataAccessApiUsageException: Multiple representations of the same entity [my.class.path.entity.resource.site.Site#738] are being merged. Detached: [FJE84 - Uckfield]; Detached: [FJE84 - Uckfield]; nested exception is java.lang.IllegalStateException: Multiple representations of the same entity [my.class.path.entity.resource.site.Site#738] are being merged. Detached: [FJE84 - Uckfield]; Detached: [FJE84 - Uckfield]
at org.springframework.orm.jpa.EntityManagerFactoryUtils.convertJpaAccessExceptionIfPossible(EntityManagerFactoryUtils.java:365)
at org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:227)
at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.translateExceptionIfPossible(AbstractEntityManagerFactoryBean.java:507)
at org.springframework.dao.support.ChainedPersistenceExceptionTranslator.translateExceptionIfPossible(ChainedPersistenceExceptionTranslator.java:61)
at org.springframework.dao.support.DataAccessUtils.translateIfNecessary(DataAccessUtils.java:242)
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:153)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:135)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
at org.springframework.data.repository.core.support.SurroundingTransactionDetectorMethodInterceptor.invoke(SurroundingTransactionDetectorMethodInterceptor.java:61)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212)
at com.sun.proxy.$Proxy122.save(Unknown Source)
at my.class.path.OfficerSubscription.run(OfficerSubscription.java:81)
at my.class.path.OfficerSubscription$$FastClassBySpringCGLIB$$705870eb.invoke(<generated>)
...

经过几天的搜索，我终于在我的春季启动项目中解决了这个问题。

在application.yaml文件中添加以下块：

spring:
jpa:
properties:
hibernate:
enable_lazy_load_no_trans: true
event:
merge:
entity_copy_observer: allow

相关内容

最新更新


热门标签：

javascript python java c# php android html jquery c++ css ios sql mysql arrays asp.net json python-3.x ruby-on-rails .net sql-server django objective-c excel regex ruby linux ajax iphone xml vba spring asp.net-mvc database wordpress string postgresql wpf windows xcode bash git oracle list vb.net multithreading eclipse algorithm macos powershell visual-studio image forms numpy scala function api selenium