Eager CDI beans

Everybody knows eager managed beans in JSF 2. @ManagedBean has an eager attribute. If eager="true" and the scope is application, then this bean must be created when the application starts and not during the first reference to the bean. This is a nice feature when you want to load application scoped data (e.g. some select items for menus) during application startup in order to increase the performance at runtime.

@ManagedBean(eager=true)
@ApplicationScoped
public class GlobalBean {
    ...
}

@ManagedBean annotation will be deprecated with JSF 2.2. It is highly recommended to use CDI (context dependency injection) beans in JEE environment. But what is the equivalent to the eager managed beans in CDI? Well, CDI is flexible, you can write portable CDI extensions. I asked Thomas Andraschko how to do this. Thomas is a CDI expert, co-owner of PrimeFaces Extensions and the committer in OpenWebBeans (OWB) project. His tip was to implement such extension as follows

@Qualifier
@Retention(RetentionPolicy.RUNTIME)
@Target({TYPE})
public @interface Eager
{
}

package mydomain.mypackage;

import java.util.ArrayList;
import java.util.List;
import javax.enterprise.context.ApplicationScoped;
import javax.enterprise.event.Observes;
import javax.enterprise.inject.spi.AfterDeploymentValidation;
import javax.enterprise.inject.spi.Bean;
import javax.enterprise.inject.spi.BeanManager;
import javax.enterprise.inject.spi.Extension;
import javax.enterprise.inject.spi.ProcessBean;

public class EagerExtension implements Extension {
    private List<Bean<?>> eagerBeansList = new ArrayList<Bean<?>>();

    public <T> void collect(@Observes ProcessBean<T> event) {
        if (event.getAnnotated().isAnnotationPresent(Eager.class)
            && event.getAnnotated().isAnnotationPresent(ApplicationScoped.class)) {
            eagerBeansList.add(event.getBean());
        }
    }

    public void load(@Observes AfterDeploymentValidation event, BeanManager beanManager) {
        for (Bean<?> bean : eagerBeansList) {
            // note: toString() is important to instantiate the bean
            beanManager.getReference(bean, bean.getBeanClass(), beanManager.createCreationalContext(bean)).toString();
        }
    }
}

The extensions should be registered in a file META-INF/services/javax.enterprise.inject.spi.Extension. The file has only one line with a fully qualified path to the EagerExtension class, e.g. mydomain.mypackage.EagerExtension.

Using is simple. Assume, we have an application scoped LayoutController CDI bean which is responsible for the entire layout configration. We can annotate it with @Eager and speed up the layout creation.

@ApplicationScoped
@Eager
@Named
public class LayoutController implements Serializable {
    private LayoutOptions layoutOptions;

    @PostConstruct
    protected void initialize() {
        layoutOptions = new LayoutOptions();

        LayoutOptions panes = new LayoutOptions();
        panes.addOption("slidable", false);
        panes.addOption("spacing", 6);
        layoutOptions.setPanesOptions(panes);

        ...
    }

    public LayoutOptions getLayoutOptions() {
        return layoutOptions;
    }
}

Have fun with CDI!

How to prevent tab changing in PrimeFaces TabView when validation failed

Trying various approaches to the question above (with p:ajax event="tabChange" and so on), I came up with a clean and well working solution. The code below turns on the PrimeFaces TabView into a "wizard mode". That means, the user stays on the same tab when he / she is trying to switch tabs and has validation errors within the current tab. The main idea is to use p:remoteCommand for a deferred decision about tab switching. If no validation errors were present, the switching occurs by the TabView widget's method select.

XHTML

<p:tabView ... widgetVar="tv_widget" styleClass="tv_selector">
    ...
</p:tabView>
           
<p:remoteCommand name="tv_remoteCommand" process="@(.tv_selector)" update="@(.tv_selector)" global="false"
        oncomplete="handleTabChangeTV(xhr, status, args, tv_widget)"/>
           
<h:panelGroup id="tv_script" styleClass="tv_selector">
    <script type="text/javascript">
          $(function(){
              bindOnClickTV(tv_remoteCommand, tv_widget);
          });
    </script>
</h:panelGroup>

JavaScript

function bindOnClickTV(rc, widget) {
    // unbind PrimeFaces click handler and bind our own
    widget.jq.find('.ui-tabs-nav > li').unbind('click.tabview').
        off('click.custom-tabview').on('click.custom-tabview', function (e) {
            var element = $(this);
       
            if ($(e.target).is(':not(.ui-icon-close)')) {
                var index = element.index();
       
                if (!element.hasClass('ui-state-disabled') && index != widget.cfg.selected) {
                    // buffer clicked tab
                    widget.clickedTab = element.index();
       
                    // call remote command
                    rc();
                }
            }
       
            e.preventDefault();
        });
}

function handleTabChangeTV(xhr, status, args, widget) {
    if (!args.validationFailed) {
        widget.select(widget.clickedTab);
    }
}