OpenSessionInViewFilter does not help, Spring + Hibernate

[Girish Vasmatkar]

Hello all,


I am using spring 2.5 and hibernate 3.2 version and a view framework ZK.

My problem is associated with Lazy association fetching. I am using OpenSessionInViewFilter and configured in web.xml successfully.
I can see it working with the spring DEBUG and I see the following out put when a request is initiated :





However, I am unable to get the Lazy loading working. I get the following exception when tried to fetch a Lazy association :

   13:41:38,125 INFO  [zkoss] session holder in ZUL  ----------------------------  org.springframework.orm.hibernate3.SessionHolder@21d2b7 current thread Thread[http-127.0.0.1-8080-4,5,jboss]
13:41:38,328 ERROR [LazyInitializationException] could not initialize proxy - no Session
org.hibernate.LazyInitializationException: could not initialize proxy - no Session
	at org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:57)
	at org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:111)
	at org.hibernate.proxy.pojo.cglib.CGLIBLazyInitializer.invoke(CGLIBLazyInitializer.java:150)
	at com.smarthopper.businessobjects.Address$$EnhancerByCGLIB$$af42f902.getAddressStreet(<generated>)
	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:597)
	at org.zkforge.apache.commons.el.ArraySuffix.evaluate(ArraySuffix.java:317)
	at org.zkforge.apache.commons.el.ComplexValue.evaluate(ComplexValue.java:143)
	at org.zkforge.apache.commons.el.ExpressionEvaluatorImpl$JSTLExpression.evaluate(ExpressionEvaluatorImpl.java:518)
	at org.zkoss.xel.el.ELXelExpression.evaluate(ELXelExpression.java:45) 

The exception stack trace also shows these lines at the start :

  at org.zkoss.zk.au.http.DHtmlUpdateServlet.process(DHtmlUpdateServlet.java:549)
	at org.zkoss.zk.au.http.DHtmlUpdateServlet.doGet(DHtmlUpdateServlet.java:441)
	at org.zkoss.zk.au.http.DHtmlUpdateServlet.doPost(DHtmlUpdateServlet.java:449)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:198)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)  

Which shows that OpenSessionInViewFilter did get called and opened the session.

For my own debugging purpose I wrote this line of code just before the line which tries to lazy load the data :

 org.springframework.orm.hibernate3.SessionHolder sessionHolder = (org.springframework.orm.hibernate3.SessionHolder)org.springframework.transaction.support.TransactionSynchronizationManager
				.getResource(org.zkoss.spring.SpringUtil.getBean("sessionFactory"));
		
		log.info("Session holder in  ----------------------------  " + sessionHolder +" current thread "+Thread.currentThread());	    

And checked to see if SessionHolder is null, but to my surprise I did get a full object and that means that there is a session bound to thread, then why am I getting the above exception.

I have also got the spring DEBUG logs which shows there is a session bound to the thread:

  

OpenSessionInViewFilter(181) - Opening single Hibernate Session in OpenSessionInViewFilter
2010-05-10 13:53:53,375 DEBUG SessionFactoryUtils(318) - Opening Hibernate Session
2010-05-10 13:53:53,375 DEBUG TransactionSynchronizationManager(186) - Bound value [org.springframework.orm.hibernate3.SessionHolder@867009] for key [org.hibernate.impl.SessionFactoryImpl@1510d11] to thread [http-8080-3]
2010-05-10 13:53:53,375 DEBUG TransactionSynchronizationManager(232) - Removed value [org.springframework.orm.hibernate3.SessionHolder@867009] for key [org.hibernate.impl.SessionFactoryImpl@1510d11] from thread [http-8080-3]
2010-05-10 13:53:53,375 DEBUG OpenSessionInViewFilter(207) - Closing single Hibernate Session in OpenSessionInViewFilter
2010-05-10 13:53:53,375 DEBUG OpenSessionInViewFilter(207) - Closing single Hibernate Session in OpenSessionInViewFilter
  

What am I doing wrong here? I simply can't get Lazy load to work, and right now I am left with nothing but to turn off Lazy loading.

[David Newton]

It's impossible to help with the information provided--the OSiV filter works, people use it all the time. It's possible there's something in the framework that renders it non-functional--have you tried doing something in a simple servlet to make sure it's working at least that far? If it is, you'd then need to start looking at how the framework handles requests.

 org.springframework.orm.hibernate3.SessionHolder sessionHolder = 
    (org.springframework.orm.hibernate3.SessionHolder) org.springframework.transaction.support.TransactionSynchronizationManager
				.getResource(org.zkoss.spring.SpringUtil.getBean("sessionFactory"));

You know about import statements, right?

[Girish Vasmatkar]

Hi David,

Thanks for the reply.

You know about import statements, right?

Actually, that code is from .zul file where I am rendering my entity (User's information) to be updated. And .zul file requires you to mention fully qualified name of the class.

"Hibernate does not support Lazy initialization for detached object"

David, could this be the reason?

If I understood this statement correctly, then is it required that you have to lazy initialize an association in the same hibernate session?

Hibernate doc says :

  s = sessions.openSession();
Transaction tx = s.beginTransaction();
            
User u = (User) s.createQuery("from User u where u.name=:userName")
    .setString("userName", userName).uniqueResult();
Map permissions = u.getPermissions();
tx.commit();
s.close();
Integer accessLevel = (Integer) permissions.get("accounts");  // Error!  

Now, what, if I do this

 s = sessions.openSession();
Transaction tx = s.beginTransaction();
            
User u = (User) s.createQuery("from User u where u.name=:userName")
    .setString("userName", userName).uniqueResult();
Map permissions = u.getPermissions();
tx.commit();
s.close();
Session ss =  sessions.openSession();
Transaction tx1 = ss.beginTransaction();
Integer accessLevel = (Integer) permissions.get("accounts");  // Now, session is there, mustn't get exception, right?   

In this case there is a session, the error mustn't appear now. Please help me get clarified on this issue, please.

[David Newton]

If the object isn't attached to any session, then the error message is correct--you'd need to associate it with the current session before lazy loading would work.

[Girish Vasmatkar]

Thanks again David for your prompt and quick reply.

So, I need to associate my detached User object with the current session and then only I will be able to fetch the association.

I am using Spring's hibernate template, which method of hibernate template I must use to bind my detached instance to current session?

Sorry, a newbie to spring and hibernate is asking you the question.

:-)

[David Newton]

No apologies necessary :) Particularly since I don't remember off the top of my head ;) I think there's a merge() method?

[Girish Vasmatkar]

Thank you David, it did the trick.

Thanks

[David Newton]

I'm always amazed when I remember something ;) Glad you got it working!