jsfjsf-2cdiview-scope

How to replace @ManagedBean / @ViewScope by CDI in JSF 2.0/2.1

I'm currently evaluating Java EE 6 / JSF 2.1 with RichFaces.

A bean which is declared as 

@ManagedBean
@ViewScoped
  1. Gets an ID set (to prepare e.g. a delete operation).
  2. Via JSF a confirmation popup is displayed.
  3. If the user confirms, the delete method is invoked and removes the row for which the ID was stored in step 1.

Since CDI beans don't have a ViewScope I tried to declare the bean as:

@Named
@ConversationScoped

Now the processing fails in step 3. because the value that was set in step 1 (checked that) is no longer available.

Do I have to use Conversation.begin() and Conversation.end() methods?

If so, where would be good place to invoke them?

Solution

  • If you can upgrade to JSF 2.2, immediately do it. It offers a native @ViewScoped annotation for CDI.

    import javax.faces.view.ViewScoped;
import javax.inject.Named;

@Named
@ViewScoped
public class Bean implements Serializable {
    // ...
}

    Alternatively, install OmniFaces which brings its own CDI compatible @ViewScoped, including a working @PreDestroy (which is broken on JSF @ViewScoped).

    import javax.inject.Named;
import org.omnifaces.cdi.ViewScoped;

@Named
@ViewScoped
public class Bean implements Serializable {
    // ...
}

    Another alternative is to install MyFaces CODI which transparently bridges JSF 2.0/2.1 @ViewScoped to CDI. This only adds an autogenerated request parameter to the URL (like @ConversationScoped would do).

    import javax.faces.bean.ViewScoped;
import javax.inject.Named;

@Named
@ViewScoped
public class Bean implements Serializable {
    // ...
}

    If you really need to use @ConversationScoped, then you indeed need to manually begin and end it. You need to @Inject a Conversation and invoke begin() in the @PostConstruct and end() in the latest step of the conversation, usually an action method which redirects to a new view.

    import javax.enterprise.context.Conversation;
import javax.enterprise.context.ConversationScoped;
import javax.inject.Named;

@Named
@ConversationScoped
public class Bean implements Serializable {

    @Inject
    private Conversation conversation;

    // ...

    @PostConstruct
    public void init() {
        conversation.begin();
    }

    public String submit() {
        // ...

        conversation.end();
        return "some.xhtml?faces-redirect=true";
    }

}

    See also: