使用spring data jpa来更新实体（无需逐个复制字段）

Question

我有一个address的新的/非托管实例和一个member的托管实例作为参数传递给以下方法：

@Override
public void modifyAddress(Member member, Address address){
    long addressId = member.getAddress().getId();//retrieving id of managed address instance
    address.setId(addressId);//setting id on unmanaged instance
    updateAddress(address);//updating unmanaged instance
}

UpdateAddress方法的实现：

 public Address PreferencesServiceImpl.updateAddress(Address address) {
        return addressRepository.save(address);
 }

正如您所看到的，我正在尝试更新地址，JPA出现以下异常：

org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect): [com.bignibou.domain.Address#5]
    org.hibernate.event.internal.DefaultMergeEventListener.entityIsDetached(DefaultMergeEventListener.java:303)
    org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:151)
    org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:76)
    org.hibernate.internal.SessionImpl.fireMerge(SessionImpl.java:903)
    org.hibernate.internal.SessionImpl.merge(SessionImpl.java:887)
    org.hibernate.internal.SessionImpl.merge(SessionImpl.java:891)
    org.hibernate.ejb.AbstractEntityManagerImpl.merge(AbstractEntityManagerImpl.java:879)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    java.lang.reflect.Method.invoke(Method.java:601)
    org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:366)
    com.sun.proxy.$Proxy122.merge(Unknown Source)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    java.lang.reflect.Method.invoke(Method.java:601)
    org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:241)
    com.sun.proxy.$Proxy121.merge(Unknown Source)
    org.springframework.data.jpa.repository.support.SimpleJpaRepository.save(SimpleJpaRepository.java:353)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    java.lang.reflect.Method.invoke(Method.java:601)
    org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.executeMethodOn(RepositoryFactorySupport.java:333)
    org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:318)
    org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:96)
    org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:260)
    org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:94)
    org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:155)
    org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    org.springframework.data.jpa.repository.support.LockModeRepositoryPostProcessor$LockModePopulatingMethodIntercceptor.invoke(LockModeRepositoryPostProcessor.java:92)
    org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:91)
    org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
    com.sun.proxy.$Proxy137.save(Unknown Source)
    com.bignibou.service.PreferencesServiceImpl_Roo_Service.ajc$interMethod$com_bignibou_service_PreferencesServiceImpl_Roo_Service$com_bignibou_service_PreferencesServiceImpl$updateAddress(PreferencesServiceImpl_Roo_Service.aj:81)
    com.bignibou.service.PreferencesServiceImpl.updateAddress(PreferencesServiceImpl.java:1)

编辑1：

我已经设置了一个示例应用程序来再现该问题。任何希望使用示例github应用程序重现问题的人都需要：

• Maven
• Git
• JDK 6
• MySQL

null

有谁能向我解释为什么在我的情况下会出现这个异常，以及如何更新地址实例而不得到这个异常吗？

Answer 1

long addressId=member.getAddress().getID（）；

数据库中已经保存了一个Member实例，并且它与数据库中已经保存的Address实例有外键关系。FK关系通过member.getAddress（）在对象模型中导航。Address实例的主键是member.getAddress().getId（）。

address.setid（addressId）

您已经在对象模型中创建了Address的另一个新实例，并手动设置为与保存在数据库中的先前存在的实例相同的主键，然后尝试保存新实体。

这是违法的。如果您希望更新一个预先存在的实体，您必须加载它，启动一个事务，修改属性并提交事务。如果希望添加新实体，则必须启动事务、创建新实例、填充其属性（包括新的唯一主键）、保存它并提交事务。

您可以通过在PK属性上使用JPA@id注释加上@generatedvalue注释（在代码的其他地方加上@sequenceGenerator/@tableGenerator注释（通常是在类上），自动填充新的唯一PK值。以下是两个教程:http://www.oracle.com/technetwork/middleware/ias/id-generation-083058.html http://www.objectdb.com/java/jpa/entity/generated