Hi,
I am new to hibernate and am using version 3.3 with Oracle 10g as DB.
I have two tables ICP and ICPCategory. ICP has field 'ICPCode' which is set as foreign key in ICPCategory.

An entry is present in the ICPCategory table with the foreign key value ICPCode from ICP (I001).

Now when I try to update the the record in ICP which has ICPCode I001 it results in lazy initialization error.
This seems to happen due to the FK relationship. But I am not changing the value of ICPCode. This happens even if I try to update without changing any field value. I am using merge() method of hibernate to update the record.

Could anyone please help me with this issue. Very Urgent.

Thanks & Regards
Ajay

Error Stack Trace
---------------------
org.springframework.orm.hibernate3.HibernateSystemException: illegal access to loading collection; nested exception is org.hibernate.LazyInitializationException: illegal access to loading collection org.springframework.orm.hibernate3.HibernateSystemException: illegal access to loading collection; nested exception is org.hibernate.LazyInitializationException: illegal access to loading collection at org.springframework.orm.hibernate3.SessionFactoryUtils.convertHibernateAccessException(SessionFactoryUtils.java:659) at org.springframework.orm.hibernate3.HibernateAccessor.convertHibernateAccessException(HibernateAccessor.java:412) at org.springframework.orm.hibernate3.HibernateTemplate.execute(HibernateTemplate.java:378) at org.springframework.orm.hibernate3.HibernateTemplate.merge(HibernateTemplate.java:769) at com.cpt.his.dao.hibernate.UniversalDaoHibernate.save(UniversalDaoHibernate.java:31) at com.cpt.his.service.impl.UniversalManagerImpl.save(UniversalManagerImpl.java:57) 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.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:301) at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:182) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149) at org.acegisecurity.intercept.method.aopalliance.MethodSecurityInterceptor.invoke(MethodSecurityInterceptor.java:66) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)

The problem is that you're closing the session and committing the transaction, despite the fact that you still need access to the objects that have been pulled from the database.

Keep the session open a bit longer, and you won't run into this problem. Take a look at the open session in view pattern and you'll get some ideas on how to solve this lazy loading exception.

Here's a little tutorial I put together on How Hibernate Works. You might find it useful, as it addresses the problem with lazy loading.

http://jpa.ezhibernate.com/Javacode/learn.jsp?tutorial=07howhibernateworks

Another option might just to be do eager loading on the entity so everything is loaded at once. Not what I like to do, but you can try it.

Hi,
Thanks for your suggestions. I looked in Open session and am a bit confused. In some places the solution seems to be to use a Session View Interceptor and in some cases the solution has been given as implementing a Session Filter. I am not sure which solution should I go in for? Could you please help me out in this?
Thanks
Ajay

I would say creating a ServletFilter that opens a transaction as the request comes in, and closes the transaction/Session as the response goes out is probably the easiest way to implement this behavior.

-Cameron McKenzie

Hi,
I tried extending the OpenSessionInViewFilter. It seems to work and for now the lazyinitialization error is not coming. Am checking more on it.
Thanks a lot for your help.

Ajay

Awesome! This is a very annoying exception to get, but once you understand why you're getting it, and how to avoid it, you won't have any problem avoiding it in the future.

Hi,
The error has cropped up again. It works in some cases and does not in others.
I always get the error in the hashCode() method that I have implemented in my POJO's. So would it be a good idea to remove the lazily loaded objects from the hashCode() method. In that case what would be the side effects? Similarly would I need to remove the lazy objects from the toString() and equals() method also.

Any ideas would be greatly appreciated.

I have posted this doubt of mine as a separate topic.
http://forum.hibernate.org/viewtopic.php?t=987709