LazyInitializationException and webflow

[Thieumdesp]

Hello,

I've got something i can't explain:

I'm trying

to display elements (a list of elements) which are lazy loaded.

after modification of those elements (and a submit), to recover those elements

I use the openSessionInViewFilter

It works fine with Spring MVC:
I have a SimpleFormController where:

in formBackingObject(...) i get an element (which contains the elements lazy loaded)

i display the view

in the onsubmit(...), i recover all i want and i can work with the collection which is now loaded

I try to do that in webflow :
I have a FormAction where :

in setupForm(...) i get an element (which contains the elements lazy loaded)

i display the view => elements lazy loaded are well displayed

in the processSubmit(...), i recover the form (which is in flow scope) but i can't work with the collection because it was not loaded !!!

i don't understand why the collection (lazy loaded) is displayed and the reason why i can work (i have a LazyInitializationException) with it in the method processSubmit(...)
in fact in debug mode, we can see that the collection have not been loaded, it's very strange because this collection was displayed in the view !!!

The way i recover the form in processSubmit(...) :

form = (SecondeReceptionForm) context.getFlowScope().getAttribute("secondeReceptionForm");

in this form there is the element which contains the elements lazy loaded

If anyone can help me, thank you very much.

[curtney]

Greeting!

You are probably calling some getXXX on the loaded object after the hibernate session is closed.

Curtney

[Colin Yates]

Not entirely sure but I would expect funny things to happen to Hibernate backed objects (if you are using OSIV which you are) if you put them in flow scope.

Anything in flow scope (actually this may depend upon your configuration) gets serialised, so you hibernate objects and their backing session will be serialised, when you next access the flow, the objects will be deserialised but the session will no longer be valid.

This might all be a croc of poo, but it might just be right

[Colin Yates]

Can you post your entire stack trace as well please

[Thieumdesp]

You are probably calling some getXXX on the loaded object after the hibernate session is closed.

That's right, but what i try to do is to make it work fine as i done it with Spring MVC

the objects will be deserialised but the session will no longer be valid.

Yes, it's exactly what happened. In processSubmit(...) i can see that the collection have not been initialized and that the Session (hibernate) is null.
I don't understand why the collection is not initialized because it is correctly displayed in the view (jsp) !!!

Can you post your entire stack trace as well please

org.springframework.webflow.ActionExecutionException: Exception thrown executing action 'com.auchan.protoSpring.web.controller.flow.SecondeReceptionController@1cd1d94' in state 'traiterSecondeReception' of flow 'secondereception'; nested exception is net.sf.hibernate.LazyInitializationException: Failed to lazily initialize a collection - no session or session was closed
net.sf.hibernate.LazyInitializationException: Failed to lazily initialize a collection - no session or session was closed
	at net.sf.hibernate.collection.PersistentCollection.initialize(PersistentCollection.java:209)
	at net.sf.hibernate.collection.PersistentCollection.read(PersistentCollection.java:71)
	at net.sf.hibernate.collection.Bag.get(Bag.java:421)
	at org.springframework.beans.BeanWrapperImpl.getPropertyValue(BeanWrapperImpl.java:672)
	at org.springframework.beans.BeanWrapperImpl.getNestedBeanWrapper(BeanWrapperImpl.java:552)
	at org.springframework.beans.BeanWrapperImpl.getBeanWrapperForPropertyPath(BeanWrapperImpl.java:530)
	at org.springframework.beans.BeanWrapperImpl.getBeanWrapperForPropertyPath(BeanWrapperImpl.java:531)
	at org.springframework.beans.BeanWrapperImpl.setPropertyValue(BeanWrapperImpl.java:726)
	at org.springframework.beans.BeanWrapperImpl.setPropertyValue(BeanWrapperImpl.java:890)
	at org.springframework.beans.BeanWrapperImpl.setPropertyValues(BeanWrapperImpl.java:917)
	at org.springframework.validation.DataBinder.applyPropertyValues(DataBinder.java:424)
	at org.springframework.validation.DataBinder.doBind(DataBinder.java:331)
	at org.springframework.web.bind.WebDataBinder.doBind(WebDataBinder.java:111)
	at org.springframework.validation.DataBinder.bind(DataBinder.java:316)
	at org.springframework.webflow.action.FormAction.doBind(FormAction.java:684)
	at org.springframework.webflow.action.FormAction.bind(FormAction.java:590)
	at com.auchan.protoSpring.web.controller.flow.SecondeReceptionController.processSubmit(SecondeReceptionController.java:60)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:324)
	at org.springframework.webflow.util.DispatchMethodInvoker.dispatch(DispatchMethodInvoker.java:231)
	at org.springframework.webflow.action.MultiAction.doExecute(MultiAction.java:138)
	at org.springframework.webflow.action.AbstractAction.execute(AbstractAction.java:225)
	at org.springframework.webflow.ActionExecutor.execute(ActionExecutor.java:65)
	at org.springframework.webflow.AnnotatedAction.execute(AnnotatedAction.java:154)
	at org.springframework.webflow.ActionExecutor.execute(ActionExecutor.java:65)
	at org.springframework.webflow.ActionState.doEnter(ActionState.java:303)
	at org.springframework.webflow.State.enter(State.java:189)
	at org.springframework.webflow.Transition.execute(Transition.java:273)
	at org.springframework.webflow.TransitionableState.onEvent(TransitionableState.java:230)
	at org.springframework.webflow.execution.FlowExecutionImpl.signalEvent(FlowExecutionImpl.java:341)
	at org.springframework.webflow.execution.FlowExecutionManager.onEvent(FlowExecutionManager.java:446)
	at org.springframework.webflow.execution.FlowExecutionManager.onEvent(FlowExecutionManager.java:389)
	at org.springframework.webflow.execution.servlet.ServletFlowExecutionManager.handle(ServletFlowExecutionManager.java:77)
	at org.springframework.webflow.mvc.FlowController.handleRequestInternal(FlowController.java:138)
	at org.springframework.web.servlet.mvc.AbstractController.handleRequest(AbstractController.java:139)
	at org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter.handle(SimpleControllerHandlerAdapter.java:44)
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:684)
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:625)
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:392)
	at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:357)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:763)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:284)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:204)
	at org.springframework.orm.hibernate.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:174)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:233)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:204)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:257)
	at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:151)
	at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:564)
	at org.apache.catalina.core.StandardContextValve.invokeInternal(StandardContextValve.java:245)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:199)
	at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:151)
	at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:564)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:195)
	at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:151)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:164)
	at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:149)
	at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:564)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:156)
	at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:151)
	at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:564)
	at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:972)
	at org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java:206)
	at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:828)
	at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:700)
	at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:584)
	at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:683)
	at java.lang.Thread.run(Thread.java:534)

[curtney]

Can you post your flow and relevant portions of your code?

Curtney

[Thieumdesp]

I know the source of the problem :
I use (try to )both :

1. OSIV (Interceptor on urlMapping bean) : Lazy Loading
2. OpenSessionInFlowListener (OSIF, listener on the FlowController) : share the same session along of a flow, it's a listner driven by FlowExecutionListenerAdapter (envent on a flow) (OSIF)

OSIV and OSIF share the same sessionFactory

Shéma :



Cases :

1. OSIV alone : I can do Lazy Loading but not share a session along a flow
2. OSIF alone : I can share a session along a flow but not lazy loading
3. OSIV + OSIF : I can share a session along a flow but i have a NPE in the OSIV Interceptor because the OSIF disconnect the hibernate session.

I tried to not disconnect the session in the OSIF but the session is put in the Flow Scope so it's serialized and a session can't be serialized if it is
connected....

It seems that i can't do Lazy Loading (OSIF) + share session along a flow (OSIF). May be i have to subclass the OSIV Interceptor to have a unique point where i manage the session and in case of flow, to put the session (hibernate) in the httpsession. My new problem here is that i don't know how to distinguish who need to share a session and who don't need...

Can someone tell me if i'm right in my explanation and how i can do Lazy Loading AND share a session along a flow ? Thanks !!!

[akw]

Can someone tell me if i'm right in my explanation and how i can do Lazy Loading AND share a session along a flow ? Thanks !!!

One advantage of the OpenSessionInFlowListener (OSIF) is that it prevents LazyLoad exceptions for all objects created in the flow's hibernate session. Furthermore, it allows optional sharing of a hibernate session between parent and child flows. If you are getting a lazy load exception while using OSIF, I would suspect that one of the following conditions exist:

1. The object that's causing the lazy load exception was loaded in a session outside the scope of the flow. This will happen if, for example, you load a user object at login and store it in your HTTP session, then later try to reference a proxied association from the user in an action method.

2. The object that's causing the lazy load exception was loaded in a parent flow and you have not configured the parent flow to allow child flows to share the parent's hibernate session. This means that the parent flow and the child flow have different hibernate sessions and that objects shared between the flows are susceptible to lazy load exceptions. You may share a parent flow's hibernate session with a child flow by adding the following to your parent's flow.xml file:
<property name="subflowsParticipateInApplicationTransaction" value="true"/>

-Alex

[Thieumdesp]

One advantage of the OpenSessionInFlowListener (OSIF) is that it prevents LazyLoad exceptions for all objects created in the flow's hibernate session. Furthermore

When i use only OSIF

Unfortunately, as the hibernate session has been disconnected in the method requestProcessed(...), it can't be use by the view to do lazy loading. And i'm not in the two cases you described :
1 : i load the object in an FormAction which is an <action-state/> of the flow
2 : i'm not in a subflow
But may be i do a bad use...

In response of http://forum.springframework.org/sho...3386#post43386 :
The aim is to do lazy loading everywhere it is necessary. it's a good idea to use an appropriate mapping, but the problem is i can't do lazy loading with OSIF.

[akw]

[B]Unfortunately, as the hibernate session has been disconnected in the method requestProcessed(...), it can't be use by the view to do lazy loading.

This is by design. We want the session to be disconnected at the completion of an HTTP request. When the next request arrives, the session will be reconnected again (see the sessionActive() method). All view rendering occurs between the time the request arrives and the time the request is complete. During this time, the hibernate session is open and connected. You can go on using objects loaded in that session (even if they were loaded in a previous request) as you would normally without the risk of lazy load exceptions.

Can you give me more information about what behavior you're seeing? Your description of the problem seems to imply that the requestProcessed() method is prematurely disconnecting the session.

Just to reiterate, the OpenSessionInViewFilter (or Interceptor) and the OpenSessionInFlowListener cannot both operate on the same HTTP request. You have to choose one or the other - this is where a filter mapping would be handy. Are you certain that you have this setup correctly?

-Alex