LIE and accessing collections in next request

[raja05]

I have a simple Seam app that displays the list of categories as a datatable and selecting a category from that. All works fine till that point. In the next request(i.e. after a category has been selected), Im trying to get the books that are associated with the category . The relation between Category to Books is OneToMany.
When trying to access the books for that category, I get the following LIE

Caused by: org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.rajasaur.bookxchange.model.Category.books, no session or session was closed
 at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:358)
 at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected(AbstractPersistentCollection.java:350)
 at org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:343)
 at org.hibernate.collection.AbstractPersistentCollection.read(AbstractPersistentCollection.java:86)
 at org.hibernate.collection.PersistentSet.iterator(PersistentSet.java:138)
 at com.rajasaur.bookxchange.action.CategoryActionsBean.updateCategory(CategoryActionsBean.java:112)
 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:585)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:112)
 at org.jboss.ejb3.interceptor.InvocationContextImpl.proceed(InvocationContextImpl.java:166)
 at org.jboss.seam.interceptors.SeamInvocationContext.proceed(SeamInvocationContext.java:56)
 at org.jboss.seam.interceptors.ValidationInterceptor.validateTargetComponent(ValidationInterceptor.java:64)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

CategoryActionsBean(Which is a Session Scoped Stateful bean) contains the following mappings.

@In(create=true)
 private EntityManager em;
 @In(required=false) @Valid
 private Category category;
 @DataModel
 private List<Category> categories;
 @DataModelSelection(value="categories") @Out(required=false, scope=ScopeType.CONVERSATION)
 private Category selectedCategory;

The Category Entity Bean also has 2 roles, category and selectedCategory, both of them in the Conversation Scope. Im totally at a loss as to why this is happening.
According to the forums, if a component is in Conversational Scope and if we use the Seam managed PC, it should work , but I cant get this to work. If I put in a em.refresh before accessing the collection , then it works fine, but I thought Seam should be able to keep the collections intact from the previous request (as per Section 9.4 in the Seam Docs).

If someone can point me to some docs or the problem, greatly appreciate it. Ive been debugging this for almost a few hours now, but cant get anywhere.

Thanks
Raja

[smokingapipe]

I think what you needed is an extended persistence context. I know that will solve the problem. Could someone give us some idea about when it's ok to use the extended persistence context? Will the system get overloaded if I have a few of them hanging around?

[raja05]

I do have a seam managed EPC.
I am debugging the code to see how Conversation managed components are kept so the LIE can be avoided.

[raja05]

I got this working after a lot of reverse engineering. Anyway, the secret was that the method starting the conversation had to somehow call the responseComplete method(by having an outcome) and then the conversation was carried between screens. In my case, since it was a factory and nothing was returned from there, the conversation was killed soon after it was started.