Question

I want to handle all <p:panel> components inside the <h:panelGroup> in the backing bean. I have bound the <h:panelGroup> to a backing bean property. But during the @PostConstruct method the property is null. During the setter of the property setPanel(), the component has no children. If I submit something using a button, then I can get the panel’s children.

What do I have to do to get the component’s children during the @PostConstruct method?

View:

<h:panelGroup binding="#{wiz.panel}">
    <p:panel header="one">
        <h:outputText value="primeiro" />
    </p:panel>

    <p:panel header="two">
        <h:outputText value="segundo" />
        <h:inputText />
    </p:panel>

    <p:panel header="three">
        <h:outputText value="terceiro" />
    </p:panel>

    <p:panel header="four">
        <h:outputText value="quarto" />
    </p:panel>
</h:panelGroup>

Backing bean

@PostConstruct
public void init() {
    if (getPanel() != null) {
        for (UIComponent comp : getPanel().getChildren()) {
            if (comp instanceof Panel) {
                System.out.println(((Panel) comp).getHeader());
            }
            System.out.println("not a panel child");
        }
    } else {
        System.out.println("panel is null");
    }
}

Answer 1

That is not possible. The @PostConstruct can be invoked long before the component tree is finished building. Rather hook on the preRenderView event. At that point the view is guaranteed to be already built. You can attach an event listener method by <f:event> in the view as follows:

<f:event type="preRenderView" listener="#{bean.init}" />

Don’t forget to remove the @PostConstruct annotation from the init() method or to rename/split the method if necessary.

Needless to say that this approach is fishy. I suggest to rethink your approach and if necessary ask a new question wherein you state the functional requirement in detail. Perhaps the ultimate answer would be just using plain EL and/or rendered attribute.