3 cascading dropdown menus with Ajax - ajax

Question

I want to modify the example "ajaxify select" in PrimeFaces showcase application and introduce a third p:selectOneMenu with chooses depending on selection of second p:selectOneMenu.
Here is the modified code :
<h:form>
<p:growl id="msgs" showDetail="true"/>
<p:panel header="Double Combo" style="margin-bottom:10px;">
<h:panelGrid columns="3" cellpadding="5">
<p:selectOneMenu id="city" value="#{pprBean.city}">
<f:selectItem itemLabel="Select City" itemValue="" />
<f:selectItems value="#{pprBean.cities}" />
<p:ajax update="suburbs"
listener="#{pprBean.handleCityChange}" />
</p:selectOneMenu>
<p:selectOneMenu id="suburbs" value="#{pprBean.suburb}">
<f:selectItem itemLabel="Select Suburb" itemValue="" />
<f:selectItems value="#{pprBean.suburbs}" />
<p:ajax update="subsuburbs"
listener="#{pprBean.handleSuburbChange}" />
</p:selectOneMenu>
<p:selectOneMenu id="subsuburbs" value="#{pprBean.subsuburb}">
<f:selectItem itemLabel="Select Subsuburb" itemValue="" />
<f:selectItems value="#{pprBean.subsuburbs}" />
</p:selectOneMenu>
</h:panelGrid>
<p:separator />
<p:commandButton value="Submit" update="msgs"
actionListener="#{pprBean.displayLocation}"/>
</p:panel>
</h:form>
But the listener function #{pprBean.handleSuburbChange} is never executed. I saw in another forum that the dynamic code in ajax response don't include tag other that tag indicated in update attribute, but how can I do then?
In PPRBean code I added:
#Named("pprBean")
#RequestScoped
public class PPRBean implements Serializable {
// ...
public void handleSuburbChange() {
if (suburb != null && !suburb.equals("")) {
subsuburbs = subsuburbsData.get(suburb);
} else {
subsuburbs = new HashMap<String, String>();
}
log.info("subsuburbs:" + subsuburbs);
}
// ...

Answer 1

The listener won't be invoked if the selected item cannot be processed. You've put the bean in the request scope which means that it's garbaged when the response associated with the request is finished (i.e. when the browser is finished loading the page). So, when you submit the form, a new request will be fired and a brand new bean is created which in your case apparently doesn't prepare/prefill the list of suburbs in the (post)constructor in order to find the selected item (and execute the listener).
To fix this, you'd normally need to put the bean in the view scope by the JSF #ViewScoped annotation along with #ManagedBean.
#ManagedBean
#ViewScoped
public class Bean {
// ...
}
This way the bean instance will live as long as you're interacting with the same view. But as you're using CDI to manage the beans instead of JSF, you'd need to use #ConversationScoped instead and control the Conversation yourself.
#Named
#ConversationScoped
public class Bean {
#Inject
private Conversation conversation;
#PostConstruct
public void init() {
conversation.begin();
// ...
}
public void submit() {
// ...
conversation.end();
}
}