1 Reply Latest reply on Apr 21, 2012 12:27 PM by sfcoy

Transactions not starting on JSF @ViewScoped @Stateless bean

kwutzke Apr 21, 2012 11:57 AM

Hello,

this is probably not the perfect forum for this, but I'll try anyway.

I have a JSF 2 @ViewScoped based webapp, that I cannot get the transactions to go with correctly, or rather: they don't start at all.

I'm using Java EE 6's CDI and EJB3, too.

Here's the main bean:

{code}    import javax.faces.bean.ManagedBean;
    import javax.faces.bean.ViewScoped;
    import javax.inject.Inject;
    ...
 
    @ManagedBean
    @ViewScoped
    @Stateless
    public class PqManager implements Serializable
    {
        private List<PqListItem> pqItems;
        
        @Inject
        private PqService pqService;
 
        public List<PqListItem> getPqItems()
        {
            if ( pqItems == null )
            {
                pqItems = pqService.findActivePqs();
            }
            
            return pqItems;
        }
 
        ...
    }{code}

The view-scoped bean is used from a JSF page to display a simple list in a datatable. It was made view-scoped because it has AJAX-based operations to add items, remove items, and to sort them via RichFaces (filtering).

I added @Stateless for every method invocation to start a transaction (or create a new one if none exists, the default is TransactionAttributeType.REQUIRED). This idea was taken from the book 'Core JavaServer Faces, 3rd ed.', however I haven't found any examples that would match my own.

Injected PqService class (it doesn't make a difference to use @EJB instead):

{code}    @Stateless
    public class PqService extends JpaCrudService
    {
        ...
        
        public List<PqListItem> findActivePqs()
        {
            return em.createQuery("SELECT NEW ... whatever not interesting here... WHERE pq.workflow = '" + Workflow.ACTIVE + "' GROUP BY pq.id", PqListItem.class).getResultList();
        }
        
        ...
    }{code}

JpaCrudService (basically taken from Adam Bien's example http://www.adam-bien.com/roller/abien/entry/generic_crud_service_aka_dao):

{code}    //@Stateless
    //@Local(CrudService.class)
    @TransactionAttribute(TransactionAttributeType.MANDATORY)
    public abstract class JpaCrudService implements CrudService
    {
        @PersistenceContext(unitName = "PqGeneratorPu")
        protected EntityManager em;
        
        @Override
        public <T> T create(T t)
        {
            em.persist(t);
            em.flush();
            em.refresh(t);
            
            return t;
        }
 
        ...
    }{code}

The only difference is that I subclass `JpaCrudService` because I don't like queries stored in/at the entities. So I omitted the @Local annotation (correct me if that's wrong). @Stateless isn't inherited AFAIK and I only inject the subclasses so I also commented that one out.

That said, the bean is then accessed from a JSF page:

{code}      <rich:dataTable value="#{pqManager.pqItems}"
                      var="pq">
        <f:facet name="header">
          <h:outputText value="Active" />
        </f:facet>
        ...{code}

However, when loading the page, I get an exception:

{code} javax.ejb.EJBTransactionRequiredException: Transaction is required for invocation: org.jboss.invocation.InterceptorContext@7a6c1c92

at org.jboss.as.ejb3.tx.CMTTxInterceptor.mandatory(CMTTxInterceptor.java:255)

at org.jboss.as.ejb3.tx.CMTTxInterceptor.processInvocation(CMTTxInterceptor.java:184)