title: Hibernate AssertionFailure: null id in entry (don't flush the Session after an exception occurs)
body: <p>AM trying to perform some update operations in a catch block when an org.hibernate.exception.ConstraintViolationException is thrown as below</p>
  
  <p>Am using Hibernate 4.3.6</p>
  
  <pre><code>try {
       services.entity.saveInstance(secQuestions)
  }
  catch(Exception e) {
       if(e instanceof org.hibernate.exception.ConstraintViolationException){
          userRegistrationRequest.requestProcessed = true
          infoMsg = userRegistrationRequest.infoMessage+' Exception: '+e.message
          userRegistrationRequest.infoMessage = infoMsg
          entityService.update(userRegistrationRequest)
          logger.info("Caught BaseApplicationException "+e.message)
          return;
   }
  </code></pre>
  
  <p>Here is my UserRegistrationRequest entity</p>
  
  <pre><code>@Audited
  @javax.persistence.Entity
  class UserRegistrationRequest implements IAmGroovy, Serializable, IVersionable {
  
  @Autowired
  protected transient Services         services;
  protected answerOne;
  protected answerTwo;
  protected emailAddress;
  protected firstName;
  protected infoMessage;
  protected lastName;
  protected requestExpired;
  protected requestProcessed;
  SecurityQuestion securityQuestionOne;  
  SecurityQuestion securityQuestionTwo; 
  UserSecurityQuestions securityQuestions;
  }
  </code></pre>
  
  <p>Here is my UserSecurityQuestions entity</p>
  
  <pre><code>@Entity
  @Audited
  public class UserSecurityQuestions implements IPersistentEntityInstance {
  
      private Long               id;
      private User               user;
      private SecurityQuestion   question1;
      private SecurityQuestion   question2;
      private String             answer1;
      private String             answer2;
      private String             hashString;
      private Timestamp          validThrough;
      private int                tries;
   }
  </code></pre>
  
  <p>Am getting the below error when try to perform update in catch block</p>
  
  <pre><code>    [Sep 17 11:48:14] ERROR | com.dc.core.common.controller.impl.BaseMultiActionController | null id in com.dc.apps.cp.security.model.UserSecurityQuestionsExt entry (don't flush the Session after an exception occurs) ERROR CODE(-1340973058)
  org.hibernate.AssertionFailure: null id in com.dc.apps.cp.security.model.UserSecurityQuestionsExt entry (don't flush the Session after an exception occurs)
    at org.hibernate.event.internal.DefaultFlushEntityEventListener.checkId(DefaultFlushEntityEventListener.java:77)
    at org.hibernate.event.internal.DefaultFlushEntityEventListener.getValues(DefaultFlushEntityEventListener.java:192)
    at org.hibernate.event.internal.DefaultFlushEntityEventListener.onFlushEntity(DefaultFlushEntityEventListener.java:152)
    at org.hibernate.event.internal.AbstractFlushingEventListener.flushEntities(AbstractFlushingEventListener.java:231)
    at org.hibernate.event.internal.AbstractFlushingEventListener.flushEverythingToExecutions(AbstractFlushingEventListener.java:102)
    at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:55)
    at org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1222)
    at com.dc.core.security.container.SecureSessionProxy.flush(SecureSessionProxy.java:306)
    at com.dc.core.operations.service.impl.OperationService.performSingleOperation(OperationService.java:778)
    at com.dc.core.presentation.presenter.impl.ScreenPresenter.performSingleOperation(ScreenPresenter.java:1187)
    at com.dc.core.presentation.controller.springmvc.impl.ItemScreenRenderController.performOperation(ItemScreenRenderController.java:952)
    at com.dc.core.presentation.controller.springmvc.impl.ItemScreenRenderController.performItemScreenOperation(ItemScreenRenderController.java:229)
    at com.dc.core.presentation.controller.springmvc.impl.ItemScreenRenderController.performOperation(ItemScreenRenderController.java:433)
    at sun.reflect.GeneratedMethodAccessor1397.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at com.dc.core.common.controller.impl.CustomMultiActionController.invokeNamedMethod(CustomMultiActionController.java:504)
    at com.dc.core.common.controller.impl.CustomMultiActionController.handleRequestInternal(CustomMultiActionController.java:430)
    at com.dc.core.common.controller.impl.BaseMultiActionController.handleRequestInternal(BaseMultiActionController.java:623)
    at org.springframework.web.servlet.mvc.AbstractController.handleRequest(AbstractController.java:154)
    at org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter.handle(SimpleControllerHandlerAdapter.java:50)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:938)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:870)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961)
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:863)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:646)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
  </code></pre>
  
  <p>If I catch Exception instead of ConstraintViolationException am seeing the below error</p>
  
  <pre><code>  Caused by: org.hibernate.exception.ConstraintViolationException: could not execute statement
      at org.hibernate.exception.internal.SQLStateConversionDelegate.convert(SQLStateConversionDelegate.java:129)
      at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49)
      at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:126)
      at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:112)
      at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:211)
      at org.hibernate.id.IdentityGenerator$GetGeneratedKeysDelegate.executeAndExtract(IdentityGenerator.java:96)
      at org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:58)
      at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3032)
      at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3558)
      at org.hibernate.action.internal.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:98)
      at org.hibernate.engine.spi.ActionQueue.execute(ActionQueue.java:490)
      at org.hibernate.engine.spi.ActionQueue.addResolvedEntityInsertAction(ActionQueue.java:195)
      at org.hibernate.engine.spi.ActionQueue.addInsertAction(ActionQueue.java:179)
      at org.hibernate.engine.spi.ActionQueue.addAction(ActionQueue.java:214)
      at org.hibernate.event.internal.AbstractSaveEventListener.addInsertAction(AbstractSaveEventListener.java:324)
      at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:288)
      at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:194)
      at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:125)
      at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:209)
      at org.hibernate.event.internal.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:55)
      at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:194)
      at org.hibernate.event.internal.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:49)
      at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:90)
      at org.hibernate.internal.SessionImpl.fireSave(SessionImpl.java:715)
      at org.hibernate.internal.SessionImpl.save(SessionImpl.java:707)
      at org.hibernate.internal.SessionImpl.save(SessionImpl.java:702)
      at com.dc.core.security.container.SecureSessionProxy.save(SecureSessionProxy.java:685)
      at com.dc.core.common.dao.impl.GenericWriteDAO.create(GenericWriteDAO.java:37)
      at com.dc.core.entity.dao.impl.EntityInstanceDAO.create(EntityInstanceDAO.java:63)
      at com.dc.core.entity.service.impl.EntityService.create(EntityService.java:278)
      at com.dc.core.api.EntityAPI.saveInstance(EntityAPI.java:188)
  
  Caused by: com.microsoft.sqlserver.jdbc.SQLServerException: Violation of UNIQUE KEY constraint 'UQ__P_USER_S__B9BE370E29ACF837'. Cannot insert duplicate key in object 'dbo.P_USER_SECURITY_QUESTIONS'. The duplicate key value is (9).
      at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDatabaseError(SQLServerException.java:216)
      at com.microsoft.sqlserver.jdbc.SQLServerStatement.getNextResult(SQLServerStatement.java:1515)
      at com.microsoft.sqlserver.jdbc.SQLServerPreparedStatement.doExecutePreparedStatement(SQLServerPreparedStatement.java:404)
      at com.microsoft.sqlserver.jdbc.SQLServerPreparedStatement$PrepStmtExecCmd.doExecute(SQLServerPreparedStatement.java:350)
      at com.microsoft.sqlserver.jdbc.TDSCommand.execute(IOBuffer.java:5696)
      at com.microsoft.sqlserver.jdbc.SQLServerConnection.executeCommand(SQLServerConnection.java:1715)
      at com.microsoft.sqlserver.jdbc.SQLServerStatement.executeCommand(SQLServerStatement.java:180)
      at com.microsoft.sqlserver.jdbc.SQLServerStatement.executeStatement(SQLServerStatement.java:155)
      at com.microsoft.sqlserver.jdbc.SQLServerPreparedStatement.executeUpdate(SQLServerPreparedStatement.java:314)
      at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:208)
      ... 162 more
  </code></pre>
  
  <p>Can someone help me, is there a better way to perform update operation in catch block?</p>