CODEWITHSUNDEEP
jsf-2initializationcdi
lostiniceland
lostiniceland

Reputation: 3789

Why is CDI-Event creating a new instance instead of using existing Oberserver?

I am facing a problem with CDI on JBoss AS 7.1.1

I have two JSF-beas, where one has the CODI ViewAccessScope (Bean A) which shows all entities, and the second is plain RequestScoped (Bean B). Each Bean get a, so called, Presenter injected which takes care of all presentation logic. So far so good.

The Presenter from Bean B is responsible for creating a new entity (calling service...bla...blubb) and when everything is done Bean B is redirecting to another page but since Bean A now has to reload its content I introduced the JEE-6 Observer.

In detail: Both Beans (A & B) get a particular Presenter injected (which has a backrefrence to the jsf-bean via a interface). Bean-B-Presenter fires an event after the entity was successfully created, so that then Bean-A-Presenter (the Observer) can reload the data and notify Bean-A about the changes.

The Problem: I am getting as NullPointerException when the observing Presenter (A) reloads its data because the reference to Bean A is lost. The reason why this happens is because CDI is obviously creating a new Presenter-object (its annotated with @Named) instead of using the one that is coupled with Bean-A.

Workaround: when I use Bean-A as the Observer than everything works.

My code is pretty much the same as seen in the link I added. I don't understand why a new instance is created when firing the event.

UPDATE regarding LightGuards comment:

The presenter beans are just annotated with @Named (which should be Dependent-Scope by default).

I had a look at the Weld-Documentation and it looks like this scope is somehow isolating my beans from each other. I need the presenters to be a new instance, each time a view (jsf-bean) gets initialized (so no Singletons). On the other hand I want to be able to send events between them, meaning that only the already existing instances get notified (not that a new instance is created).

I just did a test with the presenters being RequestScoped. This doesnt work either because now on every HTTP-Request I get a new Presenter even though the view (jsf-bean) to which it belongs is ViewAccessScoped. SessionScope of course works...but this would result in the wrong design.

Upvotes: 2

Views: 837

Answers (2)

Dar Whi
Dar Whi

Reputation: 822

Please ensure that your observers aren't private. And you have to ensure that you redirect correctly.

Upvotes: 0

LightGuard
LightGuard

Reputation: 5378

Sounds like you'll need to create your own scope for this usecase. None of the default scopes sound like they fit your need. Another option would be to look at MyFaces CODI and the conversation scope they're written.

Upvotes: 1

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