The f:ajax listener method in h:selectOneMenu is not executed

ajax jsf jsf-2

79,865

The <f:ajax> requires jsf.js file being included in the HTML <head>. It contains all JS functions for doing the JSF ajax magic.

To achieve this, ensure that you're using <h:head> instead of <head> in the master template. JSF will then automatically include the necessary <script> element there pointing to jsf.js.

<!DOCTYPE html>
<html lang="en"
    xmlns="http://www.w3.org/1999/xhtml"
    xmlns:f="http://java.sun.com/jsf/core"
    xmlns:h="http://java.sun.com/jsf/html"
    xmlns:ui="http://java.sun.com/jsf/facelets">
    <h:head>
        <title>Look, with h:head</title>
    </h:head>
    <h:body>
        Put your content here.
    </h:body>
</html>

Note that in a bit decent webbrowser with a bit decent webdeveloper toolset like Firefox's Web Developer Toolbar and/or Firebug you should immediately have noticed JS errors like jsf is undefined when the ajax request is to be executed. That should at least have given something to think about.

Update: as per your update

I've found out a few interesting things:

<f:ajax> tag doesn't work at <h:link>, <h:selectOneMenu>, <h:button>, <h:commandButton>. In this cases incorrect values in render attribute is not noticed, but incorrect value of event attribute generate an error.

<h:outputLabel>, <h:inputText> work with <f:ajax> properly.

The <h:link> and <h:button> are intented for GET requests only, not POST requests. It should however work just fine on <h:selectOneMenu> and <h:commandButton>. Don't you have more code into the complete picture which you omitted from the question for simplicity? Which JSF impl/version are you using? Are you using the right libraries in classpath? It look like that you must really have messed up something.

To convince you (and myself) I just created the following copy'n'paste'n'runnable testcase

<!DOCTYPE html>
<html lang="en"
    xmlns:h="http://java.sun.com/jsf/html" 
    xmlns:f="http://java.sun.com/jsf/core"
    xmlns:ui="http://java.sun.com/jsf/facelets"
>
    <h:head>
        <title>SO question 6089924</title>
    </h:head>
    <h:body>
        <h:form>
            <h:selectOneMenu value="#{bean.selected}">
                <f:selectItem itemValue="#{null}" itemLabel="Select..." />
                <f:selectItem itemValue="one" />
                <f:selectItem itemValue="two" />
                <f:selectItem itemValue="three" />
                <f:ajax listener="#{bean.listener}" render="result" />
            </h:selectOneMenu>
        
            <h:commandButton value="commandButton" action="#{bean.submit}">
                <f:ajax listener="#{bean.listener}" render="result" />
            </h:commandButton>
        
            <h:outputText id="result" value="#{bean.selected} #{bean.result}" />
            
            <h:messages />
        </h:form>
    </h:body>
</html>

with this bean

package com.example;

import java.io.Serializable;

import javax.faces.bean.ManagedBean;
import javax.faces.bean.ViewScoped;
import javax.faces.event.AjaxBehaviorEvent;

@ManagedBean
@ViewScoped
public class Bean implements Serializable {

    private String selected;
    private String result;

    public void submit() {
        System.out.println("submit");
    }
    
    public void listener(AjaxBehaviorEvent event) {
        System.out.println("listener");
        result = "called by " + event.getComponent().getClass().getName();
    }

    public String getSelected() {
        return selected;
    }

    public void setSelected(String selected) {
        this.selected = selected;
    }

    public String getResult() {
        return result;
    }

}

It runs fine with Mojarra 2.1.1 on Tomcat 7.0.12.

INFO: Starting Servlet Engine: Apache Tomcat/7.0.12
INFO: Initializing Mojarra 2.1.1 (FCS 20110408) for context '/playground'

79,865

Author by

kolobok

Updated on July 11, 2022

Comments

kolobok almost 2 years

The page is generated correctly with appropriate values in managed bean, but ajax events in these two h:selectOneMenus don't works. Listener is not called. An error has to be somewhere within tags, but I don't see it.

<f:view>
    <h:form>
        <h:messages />
        <h:panelGrid columns="3">

            <h:outputLabel value="Choose your faculty: *" for="faculties" />
            <h:selectOneMenu id="faculties" value="#{registrateStudent.selectedFaculty}" >
                <f:ajax event="change" listener="#{registrateStudent.genSpecializations}" execute="faculties" render="specializations" />                        
                <f:selectItems value="#{registrateStudent.listFaculty}" var="curFac" itemLabel="#{curFac.name}" itemValue="#{curFac}" />
            </h:selectOneMenu>
            <h:message id="message_faculties" for="faculties" />

            <h:outputLabel value="Choose your specialization: *" for="specializations" />
            <h:selectOneMenu id="specializations" value="#{registrateStudent.selectedSpecialization}" >
                <f:selectItems value="#{registrateStudent.listSpecialization}" var="curSpec" itemLabel="#{curSpec.name}" itemValue="#{curSpec}"/>
            </h:selectOneMenu>
            <h:message id="message_specializations" for="specializations" />

Managed Bean:

@ManagedBean(name = "registrateStudent")
@ViewScoped
public class RegistrateStudent {


    private Faculty selectedFaculty;
    private List<Faculty> listFaculty;
    private Specialization selectedSpecialization;
    private List<Specialization> listSpecialization;
    private boolean showSpecialization = false;


    /** Creates a new instance of RegistrateStudent */
    public RegistrateStudent() {
        users = new Users();
        System.out.println("poaposd1");
        student = new Student();
    }

    @PostConstruct
    public void init() {
        listFaculty = ff.findAll();
        if (listFaculty != null) {
            selectedFaculty = listFaculty.get(0);
            listSpecialization = sf.findByFaculty(selectedFaculty.getIdFaculty());
            if (listSpecialization != null) {
                selectedSpecialization = listSpecialization.get(0);
            }
            else {}
        } else {}
    }

   public void genSpecializations(AjaxBehaviorEvent event) {
        if (sf.findByFaculty(selectedFaculty.getIdFaculty()) != null) {
            this.showSpecialization = true;
        } else {
            JsfUtil.addSuccessMessage("faculties", "We don't have specializations for such faculty");
        }
    }
}

UPDATE:

I've found out a few interesting things:

<f:ajax> tag doesn't work at <h:link>, <h:selectOneMenu>, <h:button>, <h:commandButton>. In this cases incorrect values in render attribute is not noticed, but incorrect value of event attribute generate an error.

<h:outputLabel>, <h:inputText> work with <f:ajax> properly

kolobok almost 13 years

there is no any error or exception. Also I just noticed that when I change the first h:selectOneMenu, another is re-rendered, as it should, but listener is still not called.
aseychell almost 13 years

can you put a System.out.println just at the beginning of the method to make sure that it is really not being called?
kolobok almost 13 years

thanks for example. i suppose value="#{bean.selected}" is not mapped to bean's property when I move <h:form> tag under <h:selectOneMenu> because of POST request? and why h:outputLabel doesn't work without h:form even if the elements is not in this h:form?
BalusC almost 13 years

HTML input elements like <input>, <select>, <textarea> needs to go in a HTML <form> in order to get the values sent to the server. The same story applies to JSF (since all it basically does is generating a bunch of HTML). In your original question code snippet you had it right. All JSF components representing HTML input elements are in a form already. The <h:outputLabel> just renders a HTML <label> element which has no semantic form input value. You can however bind onclick actions to it.
ziMtyth over 6 years

@BalusC I've noticed that when using #{null} the "#{bean.listener}" doesn't get executed at all, how do we explain this? Is it a best practice to represent an empty selection by #{null}?
ziMtyth over 6 years

@BalusC when I use itemValue=0 the method is called, when I set itemValue to #{null} the method is not executed (I tested with prints on console). I don't think it has a relation with the link you posted.