JSF code snippet: parent-child lists

(I'm extracting a collection of JSF code snippets from my projects to keep them in a easily accessible place)
Here is an example of parent-child drop downs with multiple child selection, and the list of childs is not rendered until a parent is selected...

In the JSF page:

code:

...
< h:selectOneMenu id="parent" immediate="true"
value="#{BackingBean.selectedParent}"
valueChangeListener="#{BackingBean.changeParent}"
onchange="submit()" />
< f:selectItems value="#{BackingBean.parentsList}" >
< /h:selectManyListbox>
...
< h:selectManyListbox id="childs"
value="#{BackingBean.selectedChilds}"
rendered="#{BackingBean.parentId !=-1 }"
size="4" >
< f:selectItems value="#{BackingBean.childsList}" />
< /h:selectManyListbox>
...

In the backing bean:

code:


...
public void changeParent(ValueChangeEvent event)
{
Long parentId = (Long) event.getNewValue();
selectedChilds=new Long[0];
childList = getChildList(parentId);
}
...