What is the correct way to catch a JPA exception within an EJB

Question

I would like to understand what is the correct means of catching a JPA exception from within an EJB. Typically the exceptions would be a result of a database constraint being violated or some other database related error.

I have tried using a try/catch block around the relevant EntityManager call (e.g. remove to delete a record from a database table) but the exception is not caught. If I put a couple of System.out.println statements immediately before and after the relevant EntityManager call then both printlns appear in the system log which would suggest the EntityManager call itself isn't throwing the exception and that something else is throwing the exception.

The application I've developing uses a JSF front end, whilst I could catch the "javax.ejb.EJBException: Transaction aborted" exception and then unwrap it to find the root cause within the JSF backing bean, I would have to do the same with any other front ends that are developed in the future and potentially resulting in duplicate code.

The only solution I've managed to find so far is using an @AroundInvoke interceptor which puts a try/catch block around the InvocationContext.proceed() function call which catches a javax.persistence.PersistenceException and then unwraps the exception using the getCause() method to see whether the cause is an instanceof a number of hardcoded exceptions such as java.sql.SQLIntegrityConstraintViolationException and if the cause is found throws an custom exception which I have created. Whatever code called the EJB function can then report the exception back to the user in a user friendly way rather than as a rather unhelpful "javax.ejb.EJBException: Transaction aborted".

Whilst this approach works it doesn't seem the most elegant or correct way of catching JPA exceptions.

To provide a concrete example I have an EJB which contains a method that uses em.remove() to delete a record from a database table. Another table within the database has a foreign key constraint on this table which prevents rows from being deleted if foreign key has been used in the table.

If the @AroundInvoke interceptor is removed then the code in the EJB is as follows:

    @PersistenceContext
    private EntityManager em;

@TransactionAttribute(TransactionAttributeType.REQUIRES_NEW)
    public void deleteLocale(Locale id) {
        try {
            Object ref = em.getReference(SystemLocale.class, id);
            System.out.println("Going to execute em.remove(ref)");
            em.remove(ref);
            System.out.println("Finished executing em.remove(ref)");
        } catch (Exception e) {
            System.out.println("Caught an exception " + e.getMessage());
        }
    }

and the following exception is thrown

Local Exception Stack: 
Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.DatabaseException
Internal Exception: java.sql.SQLIntegrityConstraintViolationException: ORA-02292: integrity constraint (DEMO2_DBA.FK_SYSTEM_LOCALE) violated - child record found

Error Code: 2292
Call: DELETE FROM SYSTEM_LOCALE WHERE (LOCALE_ID = ?)
    bind => [fr-CA]
Query: DeleteObjectQuery(org.demo2.ejb.model.SystemLocale@fb5e9e3[localeId=fr_CA,localeName=test2,discontinued=true,_persistence_fetchGroup=<null>])
    at org.eclipse.persistence.exceptions.DatabaseException.sqlException(DatabaseException.java:331)
    at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.executeDirectNoSelect(DatabaseAccessor.java:895)
    at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.executeNoSelect(DatabaseAccessor.java:957)
    at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.basicExecuteCall(DatabaseAccessor.java:630)
    at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.executeCall(DatabaseAccessor.java:558)
    at org.eclipse.persistence.internal.sessions.AbstractSession.basicExecuteCall(AbstractSession.java:1995)
    at org.eclipse.persistence.sessions.server.ClientSession.executeCall(ClientSession.java:296)
    at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.executeCall(DatasourceCallQueryMechanism.java:242)
    at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.executeCall(DatasourceCallQueryMechanism.java:228)
    at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.deleteObject(DatasourceCallQueryMechanism.java:210)
    at org.eclipse.persistence.internal.queries.StatementQueryMechanism.deleteObject(StatementQueryMechanism.java:104)
    at org.eclipse.persistence.queries.DeleteObjectQuery.executeDatabaseQuery(DeleteObjectQuery.java:218)
    at org.eclipse.persistence.queries.DatabaseQuery.execute(DatabaseQuery.java:899)
    at org.eclipse.persistence.queries.DatabaseQuery.executeInUnitOfWork(DatabaseQuery.java:798)
    at org.eclipse.persistence.queries.ObjectLevelModifyQuery.executeInUnitOfWorkObjectLevelModifyQuery(ObjectLevelModifyQuery.java:108)
    at org.eclipse.persistence.queries.DeleteObjectQuery.executeInUnitOfWorkObjectLevelModifyQuery(DeleteObjectQuery.java:119)
    at org.eclipse.persistence.queries.ObjectLevelModifyQuery.executeInUnitOfWork(ObjectLevelModifyQuery.java:85)
    at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.internalExecuteQuery(UnitOfWorkImpl.java:2894)
    at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1797)
    at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1779)
    at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1730)
    at org.eclipse.persistence.internal.sessions.CommitManager.deleteAllObjects(CommitManager.java:336)
    at org.eclipse.persistence.internal.sessions.CommitManager.deleteAllObjects(CommitManager.java:285)
    at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.commitToDatabase(UnitOfWorkImpl.java:1442)
    at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.commitToDatabaseWithChangeSet(UnitOfWorkImpl.java:1529)
    at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.issueSQLbeforeCompletion(UnitOfWorkImpl.java:3166)
    at org.eclipse.persistence.internal.sessions.RepeatableWriteUnitOfWork.issueSQLbeforeCompletion(RepeatableWriteUnitOfWork.java:352)
    at org.eclipse.persistence.transaction.AbstractSynchronizationListener.beforeCompletion(AbstractSynchronizationListener.java:158)
    at org.eclipse.persistence.transaction.JTASynchronizationListener.beforeCompletion(JTASynchronizationListener.java:68)
    at com.sun.enterprise.transaction.JavaEETransactionImpl.commit(JavaEETransactionImpl.java:452)
    at com.sun.enterprise.transaction.JavaEETransactionManagerSimplified.commit(JavaEETransactionManagerSimplified.java:854)
    at com.sun.ejb.containers.EJBContainerTransactionManager.completeNewTx(EJBContainerTransactionManager.java:719)
    at com.sun.ejb.containers.EJBContainerTransactionManager.postInvokeTx(EJBContainerTransactionManager.java:515)
    at com.sun.ejb.containers.BaseContainer.postInvokeTx(BaseContainer.java:4475)
    at com.sun.ejb.containers.BaseContainer.postInvoke(BaseContainer.java:2009)
    at com.sun.ejb.containers.BaseContainer.postInvoke(BaseContainer.java:1979)
    at com.sun.ejb.containers.EJBLocalObjectInvocationHandler.invoke(EJBLocalObjectInvocationHandler.java:220)
    at com.sun.ejb.containers.EJBLocalObjectInvocationHandlerDelegate.invoke(EJBLocalObjectInvocationHandlerDelegate.java:88)
    at com.sun.proxy.$Proxy330.deleteLocale(Unknown Source)
    at org.demo2.ejb.service.__EJB31_Generated__SystemLocaleBoundary__Intf____Bean__.deleteLocale(Unknown Source)
    at org.demo2.web.controller.SystemLocaleBacking.deleteLocale(SystemLocaleBacking.java:117)
    at org.demo2.web.controller.SystemLocaleBacking$Proxy$_$$_WeldClientProxy.deleteLocale(Unknown Source)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at com.sun.el.parser.AstValue.invoke(AstValue.java:275)
    at com.sun.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:304)
    at org.jboss.weld.util.el.ForwardingMethodExpression.invoke(ForwardingMethodExpression.java:40)
    at org.jboss.weld.el.WeldMethodExpression.invoke(WeldMethodExpression.java:50)
    at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105)
    at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:87)
    at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
    at javax.faces.component.UICommand.broadcast(UICommand.java:315)
    at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:790)
    at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1282)
    at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:81)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
    at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:198)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:646)
    at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:344)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214)
    at org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:112)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214)
    at org.apache.catalina.core.ApplicationDispatcher.doInvoke(ApplicationDispatcher.java:873)
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:739)
    at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:575)
    at org.apache.catalina.core.ApplicationDispatcher.doDispatch(ApplicationDispatcher.java:546)
    at org.apache.catalina.core.ApplicationDispatcher.dispatch(ApplicationDispatcher.java:428)
    at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:378)
    at org.omnifaces.facesviews.FacesViewsForwardingFilter.doFilter(FacesViewsForwardingFilter.java:143)
    at org.omnifaces.filter.HttpFilter.doFilter(HttpFilter.java:77)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214)
    at org.demo2.web.servlet.ClickjackFilter.doFilter(ClickjackFilter.java:28)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214)
    at org.demo2.web.servlet.NoCacheFilter.doFilter(NoCacheFilter.java:30)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214)
    at org.apache.shiro.web.servlet.ProxiedFilterChain.doFilter(ProxiedFilterChain.java:61)
    at org.apache.shiro.web.servlet.AdviceFilter.executeChain(AdviceFilter.java:108)
    at org.apache.shiro.web.servlet.AdviceFilter.doFilterInternal(AdviceFilter.java:137)
    at org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:125)
    at org.apache.shiro.web.servlet.ProxiedFilterChain.doFilter(ProxiedFilterChain.java:66)
    at org.apache.shiro.web.servlet.AdviceFilter.executeChain(AdviceFilter.java:108)
    at org.apache.shiro.web.servlet.AdviceFilter.doFilterInternal(AdviceFilter.java:137)
    at org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:125)
    at org.apache.shiro.web.servlet.ProxiedFilterChain.doFilter(ProxiedFilterChain.java:66)
    at org.apache.shiro.web.servlet.AbstractShiroFilter.executeChain(AbstractShiroFilter.java:449)
    at org.apache.shiro.web.servlet.AbstractShiroFilter$1.call(AbstractShiroFilter.java:365)
    at org.apache.shiro.subject.support.SubjectCallable.doCall(SubjectCallable.java:90)
    at org.apache.shiro.subject.support.SubjectCallable.call(SubjectCallable.java:83)
    at org.apache.shiro.subject.support.DelegatingSubject.execute(DelegatingSubject.java:383)
    at org.apache.shiro.web.servlet.AbstractShiroFilter.doFilterInternal(AbstractShiroFilter.java:362)
    at org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:125)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:316)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160)
    at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734)
    at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673)
    at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174)
    at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:357)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:260)
    at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:188)
    at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:191)
    at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:168)
    at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:189)
    at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:288)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:206)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:136)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:114)
    at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
    at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:838)
    at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:113)
    at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:115)
    at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:55)
    at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:135)
    at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:564)
    at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:544)
    at java.lang.Thread.run(Thread.java:744)
Caused by: java.sql.SQLIntegrityConstraintViolationException: ORA-02292: integrity constraint (DEMO2_DBA.FK_SYSTEM_LOCALE) violated - child record found

    at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:447)
    at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:396)
    at oracle.jdbc.driver.T4C8Oall.processError(T4C8Oall.java:951)
    at oracle.jdbc.driver.T4CTTIfun.receive(T4CTTIfun.java:513)
    at oracle.jdbc.driver.T4CTTIfun.doRPC(T4CTTIfun.java:227)
    at oracle.jdbc.driver.T4C8Oall.doOALL(T4C8Oall.java:531)
    at oracle.jdbc.driver.T4CPreparedStatement.doOall8(T4CPreparedStatement.java:208)
    at oracle.jdbc.driver.T4CPreparedStatement.executeForRows(T4CPreparedStatement.java:1046)
    at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:1336)
    at oracle.jdbc.driver.OraclePreparedStatement.executeInternal(OraclePreparedStatement.java:3613)
    at oracle.jdbc.driver.OraclePreparedStatement.executeUpdate(OraclePreparedStatement.java:3694)
    at oracle.jdbc.driver.OraclePreparedStatementWrapper.executeUpdate(OraclePreparedStatementWrapper.java:1354)
    at com.sun.gjc.spi.base.PreparedStatementWrapper.executeUpdate(PreparedStatementWrapper.java:125)
    at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.executeDirectNoSelect(DatabaseAccessor.java:885)
    ... 124 more
]]

The application is running on GlassFish version 4.0 and is using EclipseLink as the JPA provider but I would like to avoid using any EclipseLink specific code to maintain portability.

So in summary my question is what is the correct means of catching a JPA exception from within an EJB?

Answer 1

No need to use @AroundInvoke

You must follow the .persist(), .merge(), or .remove() with a .flush() this will force the exception to be thrown at that spot if one happens. Without flush, JPA closes the transaction at a later period, and that is were the exception is being thrown (out of catch range).

Then when the exception is caught, do this to get the root problem.

while(e.getCause() != null) {
   e = e.getCause();
}
System.out.println(e.getMessage());

That is where you will see the JPA message