0 Replies Latest reply on Oct 31, 2011 8:09 AM by ben_utzer

ConversationScoped example

ben_utzer Oct 31, 2011 8:09 AM

I wonder why there is no example contained in the Weld distribution that makes use of the conversation scope. Is it by default unusable?

I find the following to be the basic use case for conversation scope:

@Named
@ConversationScoped
public class PersonView implements Serializable {

     @Inject
     private PersonService personService;
     
     @Inject
     private Conversation conversation;

     private Person person;

     @Produces
     @Named
     public Person getPerson() {
          return person;
     }

     public void setPerson(Person person){
          this.person = person;
     }

     public String save() {
          this.personService.save(person);
          this.conversation.end();
          return "success";
     }

     @PostConstruct
     public void loadPerson() {
          if(this.conversation.isTransient()) {
               this.conversation.begin();
          }
          this.person=personService.ladeAzubi(3L);
     }

}


@Stateless
@Named
public class PersonService implements Serializable {

     @PersistenceContext
     private EntityManager em;

     public Person save(Person person) {

          return em.merge(person);
     }

     public Person loadPerson(long id) {
          return em.find(Person.class, id);
     }

}

page1.xhtml:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
     xmlns:ui="http://java.sun.com/jsf/facelets"
     xmlns:f="http://java.sun.com/jsf/core"
     xmlns:h="http://java.sun.com/jsf/html">
<h:form>
     <h:inputText value="#{person.vorname}" />
     <h:commandLink action="page2" value="Continue" />
</h:form>
</html>

page2.xhtml:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
     xmlns:ui="http://java.sun.com/jsf/facelets"
     xmlns:f="http://java.sun.com/jsf/core"
     xmlns:h="http://java.sun.com/jsf/html">
<h:form>
     <h:inputText value="#{person.lastname}" />
     <h:commandLink action="#{personView.save}" value="save" />
</h:form>
</html>

success.xhtml:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
     xmlns:ui="http://java.sun.com/jsf/facelets"
     xmlns:f="http://java.sun.com/jsf/core"
     xmlns:h="http://java.sun.com/jsf/html">Sauber. Azubi
#{person.lastname}, #{person.firstname} saved successfully.
</html>

This is actually not working as expected. The @PostConstructed loadPerson-method is invoked twice so two conversations are started. Once on first get request and the second time on the first postback after I hit Continue.

Moreover, I found that redirect doesn't seem to be supported. While this wizard works with forwarding when I change the commandlink action on page1 and add ?faces-redirect=true then the conversation id gets added twice and a new conversation is started. Quite sad.

Another thing that seems broken to me is how a page refresh is handled when the conversation has ended: a org.jboss.weld.context.NonexistentConversationException occurs.

Has there been any real world use of the conversation scope or is this just some marketing joke? I also heard about problems handling concurrent ajax requests.