[Contrib: Evaluation System] Help with DB transactions when using AuthoringService API

Fri Jan 22 06:48:56 PST 2010

Hi Aaron,

I am trying to make calls to the AuthoringService from a servlet that  
reads XML from a file and attempts to create various types of EVALSYS  
entities.  The servlet reads a file that defines an EvalScale and  
several EvalItem entities.  The EvalScale (with eid of '1') is created  
(or updated if the file is read again) with no problem.  Then the  
servlet reads the XML for the first EvalItem. After deserializing the  
XML into an EvalItem object named "newItem" and doing some validation  
and fix-up, the new item is saved or updated, as follows:

         EvalItem item =  
this.getAuthoringService().getItemByEid(newItem.getEid());  // <---  
line 404
         if(item == null) {
             //save new item
         	item = newItem;
             event = EVENT_ITEM_SAVE;
         } else {
             //update existing
             setProperties(item, newItem);
             event = EVENT_ITEM_UPDATE;
         }

         //save or update
         this.getAuthoringService().saveItem(item, currentUserId);  //  
<--- line 417

Similar code works just fine for creating or updating an EvalScale,  
but an exception is thrown when we try to update the EvalItem:

org.springframework.orm.hibernate3.HibernateSystemException: a  
different object with the same identifier value was already associated  
with the session: [org.sakaiproject.evaluation.model.EvalItem#68];  
nested exception is org.hibernate.NonUniqueObjectException: a  
different object with the same identifier value was already associated  
with the session: [org.sakaiproject.evaluation.model.EvalItem#68]

There's a stack trace at the end of the message.

It seems like the exception message says that we have retrieved the  
EvalItem entity with id of 68 and now we're trying to save a different  
java object with the id 68 in the same session.  When debugging, the  
java object retrieved in line 404 is object 27538 and has an id of  
68.  When we attempt to save it in line 417, it is the same object  
(27538) and has the same id (68).

Any suggestions about what might be going on here?

One thing is that the EvalItem has a reference to an EvalScale.  Part  
of the fix-up is to get the EID of the EvalScale from the XML,  
retrieve the EvalScale that has that EID and add it to the EvalItem by  
a call to EvalItem.setScale(EvalScale scale).  I've seen that work in  
code that does not have the problem I'm having.

Thanks.

Jim

2010-01-22 09:27:58,507  WARN http-8080-Processor24  
org.sakaiproject.evalport.servlet.EvalExchangeServlet - EvalItem with  
eid '1' was not saved/updated in the database
org.springframework.orm.hibernate3.HibernateSystemException: a  
different object with the same identifier value was already associated  
with the session: [org.sakaiproject.evaluation.model.EvalItem#68];  
nested exception is org.hibernate.NonUniqueObjectException: a  
different object with the same identifier value was already associated  
with the session: [org.sakaiproject.evaluation.model.EvalItem#68]
Caused by:
org.hibernate.NonUniqueObjectException: a different object with the  
same identifier value was already associated with the session:  
[org.sakaiproject.evaluation.model.EvalItem#68]
	at  
org 
.hibernate 
.engine 
.StatefulPersistenceContext 
.checkUniqueness(StatefulPersistenceContext.java:590)
	at  
org 
.hibernate 
.event 
.def 
.DefaultSaveOrUpdateEventListener 
.performUpdate(DefaultSaveOrUpdateEventListener.java:284)
	at  
org 
.hibernate 
.event 
.def 
.DefaultSaveOrUpdateEventListener 
.entityIsDetached(DefaultSaveOrUpdateEventListener.java:223)
	at  
org 
.hibernate 
.event 
.def 
.DefaultUpdateEventListener 
.performSaveOrUpdate(DefaultUpdateEventListener.java:33)
	at  
org 
.hibernate 
.event 
.def 
.DefaultSaveOrUpdateEventListener 
.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:70)
	at org.hibernate.impl.SessionImpl.fireUpdate(SessionImpl.java:564)
	at org.hibernate.impl.SessionImpl.update(SessionImpl.java:552)
	at org.hibernate.impl.SessionImpl.update(SessionImpl.java:544)
	at org.springframework.orm.hibernate3.HibernateTemplate 
$14.doInHibernate(HibernateTemplate.java:657)
	at  
org 
.springframework 
.orm.hibernate3.HibernateTemplate.execute(HibernateTemplate.java:372)
	at  
org 
.springframework 
.orm.hibernate3.HibernateTemplate.update(HibernateTemplate.java:654)
	at  
org 
.springframework 
.orm.hibernate3.HibernateTemplate.update(HibernateTemplate.java:650)
	at  
org 
.sakaiproject 
.genericdao 
.hibernate.HibernateGenericDao.baseUpdate(HibernateGenericDao.java:360)
	at  
org 
.sakaiproject 
.genericdao 
.hibernate.HibernateGenericDao.update(HibernateGenericDao.java:650)
	at  
org 
.sakaiproject 
.genericdao 
.hibernate.HibernateGenericDao.save(HibernateGenericDao.java:670)
	at sun.reflect.GeneratedMethodAccessor505.invoke(Unknown Source)
	at  
sun 
.reflect 
.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java: 
25)
	at java.lang.reflect.Method.invoke(Method.java:592)
	at  
org 
.springframework 
.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:296)
	at  
org 
.springframework 
.aop 
.framework 
.ReflectiveMethodInvocation 
.invokeJoinpoint(ReflectiveMethodInvocation.java:177)
	at  
org 
.springframework 
.aop 
.framework 
.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:144)
	at  
org 
.springframework 
.transaction 
.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java: 
107)
	at  
org 
.springframework 
.aop 
.framework 
.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:166)
	at  
org 
.springframework 
.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
	at $Proxy8.save(Unknown Source)
	at  
org 
.sakaiproject 
.evaluation 
.logic 
.EvalAuthoringServiceImpl 
.saveItem_aroundBody28(EvalAuthoringServiceImpl.java:436)
	at  
org 
.sakaiproject 
.evaluation 
.logic 
.EvalAuthoringServiceImpl 
.saveItem_aroundBody29$advice(EvalAuthoringServiceImpl.java:84)
	at  
org 
.sakaiproject 
.evaluation 
.logic.EvalAuthoringServiceImpl.saveItem(EvalAuthoringServiceImpl.java: 
1)
	at sun.reflect.GeneratedMethodAccessor507.invoke(Unknown Source)
	at  
sun 
.reflect 
.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java: 
25)
	at java.lang.reflect.Method.invoke(Method.java:592)
	at  
org 
.springframework 
.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:296)
	at  
org 
.springframework 
.aop 
.framework 
.ReflectiveMethodInvocation 
.invokeJoinpoint(ReflectiveMethodInvocation.java:177)
	at  
org 
.springframework 
.aop 
.framework 
.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:144)
	at  
org 
.springframework 
.transaction 
.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java: 
107)
	at  
org 
.springframework 
.aop 
.framework 
.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:166)
	at  
org 
.springframework 
.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
	at $Proxy18.saveItem(Unknown Source)
	at  
org 
.sakaiproject 
.evalport 
.servlet 
.EvalExchangeServlet.saveOrUpdateItems(EvalExchangeServlet.java:417)
	at  
org 
.sakaiproject 
.evalport.servlet.EvalExchangeServlet.process(EvalExchangeServlet.java: 
215)
	at  
org 
.sakaiproject 
.evalport.servlet.EvalExchangeServlet.doPost(EvalExchangeServlet.java: 
186)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
	at  
org 
.apache 
.catalina 
.core 
.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java: 
269)
	at  
org 
.apache 
.catalina 
.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
	at org.sakaiproject.util.RequestFilter.doFilter(RequestFilter.java:616)
	at  
org 
.apache 
.catalina 
.core 
.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java: 
215)
	at  
org 
.apache 
.catalina 
.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
	at  
org 
.apache 
.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java: 
213)
	at  
org 
.apache 
.catalina.core.StandardContextValve.invoke(StandardContextValve.java: 
174)
	at  
org 
.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java: 
127)
	at  
org 
.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java: 
117)
	at  
org 
.apache 
.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
	at  
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java: 
151)
	at  
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java: 
874)
	at org.apache.coyote.http11.Http11BaseProtocol 
$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
	at  
org 
.apache 
.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
	at  
org 
.apache 
.tomcat 
.util 
.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java: 
81)
	at org.apache.tomcat.util.threads.ThreadPool 
$ControlRunnable.run(ThreadPool.java:689)
	at java.lang.Thread.run(Thread.java:613)