Howto handle LazyInitializationException

[thierry.rietsch]

Hello

I have a problem with lazy loading and need a workaround.

I have an Entity called SoftwareInventoryObject which contains a Collection of SoftwareInventoryObjectParts.

class SoftwareInventoryObject {
 // other fields
 List<SoftwareInventoryObjectPart> parts;

 // Getter & Setter
}

Additionally I have a EJB3 Bean SoftwareObjectSearch which searchs in the database for the above mentioned SoftwareInventoryObjects.

class SoftwareObjectSearch {
 // other code

 @DataModel
 List<SoftwareObjectPart> inventoryObjects;

 // other code
}

To view the result I have a facelet which contains a <h:dataTable>. Now I would like to display each of the SoftwareObjectParts too therefor I have a nested <h:dataTable> in the facelet.

<h:dataTable value="#{inventoryObjects}" var="sio" rendered="#{inventoryObjects != null}">
 <h:column>
 <h:dataTable value="#{sio.parts}" var="siop">
 <h:column><f:facet name="header">Name</f:facet> #{sio.name}</h:column>
 <h:column><f:facet name="header">Type</f:facet> #{sio.type}</h:column>
 <h:column><f:facet name="header">Barcode</f:facet> #{sio.barcode}</h:column>
 <h:column><f:facet name="header">Manufacture</f:facet> #{sio.manufacture}</h:column>
 <h:column><f:facet name="header">Distributor</f:facet> #{siop.distributor}</h:column>
 <h:column><f:facet name="header">Order Number</f:facet> #{siop.orderNumber}</h:column>
 <h:column><f:facet name="header">Price</f:facet> #{siop.price}</h:column>
 <h:column><f:facet name="header">Version</f:facet> #{siop.version}</h:column>
 <h:column><f:facet name="header">Action</f:facet> link</h:column>
 </h:dataTable>
 </h:column>
</h:dataTable>

Now when I run a facelet I get a Lazy Initalization Exception for the siop, the SoftwareInventoryObjectPart. This makes sense to me, because I access a collection which is not eager loaded, after the initial Hibernate session was closed. My question is now, how can I avoid such an exception? What is a nice workaround.

If you need any further code please let me know. Thanks for all the answers in advance.

Thierry

[jazir1979]

Hi Thierry,

Have you read about the extended persistence context?

If not, this is where your answer lies http://docs.jboss.com/seam/1.2.1.GA/reference/en/html/persistence.html

Using a conversation-scoped SFSB with an extended persistence context will solve your problem.

Daniel.

[thierry.rietsch]

Thank you for your reply. I have read through the articel in the JBoss Seam documentation. Unfortunately I din't fully understand it. Is there an example of an extended persistence context in the jboss-seam examples?

Thanks again for your reply and your help,

thierry

[thierry.rietsch]

Now I got it. Sorry. I use now:

class SoftwareObjectSearchBean {
 // other code

 @PersistenceContext(type=PersistenceContextType.EXTENDED)
 EntityManager em;

 // other code
}

Is that the right way?

[gavin.king]

That is one way, but a better way is to use a Seam-managed PC.

[trickyvail]

That is one way, but a better way is to use a Seam-managed PC.

The "Seam-managed Persistence Context (PC)" you refer to is an Extended Persistence Context that is stored inside a Seam Conversation Scope?

[trickyvail]

Seam managed persistence contexts are explained in the Seam documentation in section 8.3 page 107.