This question already has answers here:
Identifying and solving javax.el.PropertyNotFoundException: Target Unreachable
(18 answers)
Closed 6 years ago.
I try write my first JSF2.0 project (with using EJB3.1). I don't understand why my #ManagedBean annotation not work.
I always get an error, when I run application on Glassfish v3
exception
javax.servlet.ServletException: /login.xhtml #34,133
value="#{loginBean.login}": Target Unreachable, identifier 'loginBean'
resolved to null
root cause
javax.el.PropertyNotFoundException: /login.xhtml #34,133
value="#{loginBean.login}": Target Unreachable, identifier 'loginBean'
resolved to null
If I define a managed bean in faces-config.xml - it will work. But I want to use annotation.
May be I use wrong libraries in my poms?
Example of managedbean (it will be a transfer object):
package edu.tsystems.vmmail.web.core.domain;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.ViewScoped;
import java.io.Serializable;
#ManagedBean
#ViewScoped
public class LoginBean implements Serializable {
private String login;
private String password;
public LoginBean() {}
public String getLogin() {
return login;
}
public void setLogin(String login) {
this.login = login;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
login.xhtml (where i can try to use it):
<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:p="http://primefaces.org/ui">
<f:loadBundle var="common" basename="edu.tsystems.vmmail.web.ui.MessageResources" />
<h:head>
<title>Welcome to VMMail Web Interface</title>
<link type="text/css" href="#{request.contextPath}/css/style.css" rel="stylesheet" />
</h:head>
<h:body>
<f:view>
<h:form id="loginForm" method="post">
<p:panelGrid id="mainLogin" styleClass="noInnerBorderTable">
<f:facet name="header">
<p:row>
<p:column colspan="4">
<h:outputText value="#{common['login.welcome']}" /><br/>
<h:message for="loginBean" id="login1Error" />
</p:column>
</p:row>
</f:facet>
<p:row>
<p:column rowspan="2">
<div class="logoCell"></div>
</p:column>
<p:column>
<h:outputText value="#{common['field.login']}" for="loginBean" />
</p:column>
<p:column>
<p:inputText id="loginBean" required="true" value="#{loginBean.login}" requiredMessage="#{common['field.login.required']}" />
</p:column>
<p:column rowspan="2">
<div class="submitButtonCell">
<p:commandLink styleClass="loginAnchor" title="#{common['field.loginButton']}"
action="#{userController.loggingIn(login)}" ajax="false" />
</div>
</p:column>
</p:row>
<p:row>
<p:column>
<h:outputText for="password" value="#{common['field.password']}" />
</p:column>
<p:column>
<p:password id="password" required="true" value="#{loginBean.password}" requiredMessage="#{common['field.password.required']}" />
</p:column>
</p:row>
<f:facet name="footer">
<p:row>
<p:column colspan="4">
<h:outputText value="#{common['login.notHave']}" />
<a href="#{request.contextPath}/registration.xhtml">
<h:outputText value="#{common['login.registerNow']}" />
</a>
</p:column>
</p:row>
</f:facet>
</p:panelGrid>
</h:form>
</f:view>
</h:body>
</html>
UserController class:
package edu.tsystems.vmmail.web.core.controllers;
import edu.tsystems.vmmail.web.core.dao.UserDAO;
import edu.tsystems.vmmail.web.core.domain.LoginBean;
import edu.tsystems.vmmail.web.core.model.UserEntity;
import javax.ejb.EJB;
import javax.ejb.Stateless;
import javax.faces.application.FacesMessage;
import javax.faces.bean.ViewScoped;
import javax.faces.context.FacesContext;
import javax.servlet.http.HttpSession;
#Stateless
#ViewScoped
public class UserController {
#EJB
private UserDAO userDAO;
private UserEntity user;
public boolean isLoggedIn() {
return user != null;
}
public String loggingIn(LoginBean loginBean) {
FacesContext context = FacesContext.getCurrentInstance();
if(userDAO == null) {
context.addMessage("loginForm:login1Error", new FacesMessage("DAO IS NULL!"));
// return "/loginBean.xhtml?faces-redirect=true&error=1";
}
user = userDAO.getUserByLoginAndPassword(loginBean.getLogin(), loginBean.getPassword());
if (user != null) {
FacesContext facesContext = FacesContext.getCurrentInstance();
HttpSession session = (HttpSession) facesContext.getExternalContext().getSession(false);
session.setAttribute("user", user.getId());
return "/mail/mail.xhtml?faces-redirect=true";
} else {
return "/loginBean.xhtml?faces-redirect=true";
}
}
public String logout() {
FacesContext.getCurrentInstance().getExternalContext().invalidateSession();
return "/login.xhmtl?faces-redirect=true";
}
}
I really not understand why it not works :( What do I do wrong?
UPD: Stack trace: http://pastebin.com/istJmMHr
Source code may be downloaded from my google drive: https://docs.google.com/file/d/0B4Am7SXJwmtKNVc0LVhWVlEyMVk/view
I think you can better start with a really small example to get a grasp of things. There are many things not quite right in your code.
To start, an #Stateless bean can't be view scoped. Think about this for a moment. What would it actually mean to have a stateless view scoped bean? Why did you think you needed one in the first place?
A view should have one backing bean and this one is often view scoped. Any DTOs that you might need for that view should not be view scoped, but should just be instance variables of the main backing bean. That way they'll be automatically dependent on that scope.
In your case, make loginBean an instance variable just like the user variable.
It happend because my #ManagedBean was placed in EJB package, not in WAR package.
When I moved all #ManagedBeans into my WAR module all earned!
Related
I wanted process data from other bean, in ActionListener method, but it throw NullPointerException, so i try resafe instance of bean to next instance in init() method with #PostConstruct annotation, but it still throw NullPointerException. I know that can obtain bean throught FacesContext.getCurrentInstance().getApplication().evaluateExpressionGet(context, expression, expectedType);but is it possible throught #ManagedProperty? This is the code:
Login.java
package sklad;
import javax.annotation.PostConstruct;
import javax.faces.application.FacesMessage;
import javax.faces.bean.ManagedProperty;
import javax.faces.context.FacesContext;
import javax.faces.event.AbortProcessingException;
import javax.faces.event.ActionEvent;
import javax.faces.event.ActionListener;
public class Login implements ActionListener{
private Osoba os;
#ManagedProperty(value="#{osoba}")
private Osoba osoba;
#PostConstruct
public void init(){
os = osoba;
}
#Override
public void processAction(ActionEvent a) throws AbortProcessingException {
FacesContext context = FacesContext.getCurrentInstance();
context.addMessage("zprava", new FacesMessage(os.getId().toString() + " " + os.getHeslo()));
}
public Osoba getOsoba() {
return osoba;
}
public void setOsoba(Osoba osoba) {
this.osoba = osoba;
}
public Osoba getOs() {
return os;
}
public void setOs(Osoba os) {
this.os = os;
}
}
Osoba.java
package sklad;
import javax.faces.application.FacesMessage;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.SessionScoped;
import javax.faces.context.FacesContext;
import javax.faces.event.ActionEvent;
#ManagedBean
#SessionScoped
public class Osoba{
private Integer id;
private String heslo;
public Osoba(){}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getHeslo() {
return heslo;
}
public void setHeslo(String heslo) {
this.heslo = heslo;
}
}
login.xhtml
<!DOCTYPE html>
<html xmlns:h="http://xmlns.jcp.org/jsf/html"
xmlns:f="http://xmlns.jcp.org/jsf/core"
xmlns:p="http://primefaces.org/ui">
<h:head>
<title>title</title>
<link rel="stylesheet" type="text/css" href="../styles/login.css" />
</h:head>
<h:body>
<p:growl id="growl" showDetail="true" life="3000" />
<p:panel id="panel_login" header="Přihlášení" styleClass="panel">
<p:panelGrid styleClass="panelGrid">
<h:form>
<p:row>
<p:column>
<h:outputText value="ID: " />
</p:column>
<p:column>
<h:inputText id="id_login" value="${osoba.id}" />
</p:column>
</p:row>
<p:row>
<p:column>
<h:outputText value="Heslo: " />
</p:column>
<p:column>
<h:inputSecret id="heslo_login" value="${osoba.heslo}" />
</p:column>
</p:row>
<p:row>
<p:column colspan="2">
<h:commandButton id="btn_login" value="Přihlásit">
<f:actionListener type="sklad.Login"/>
</h:commandButton>
</p:column>
</p:row>
</h:form>
</p:panelGrid>
</p:panel>
</h:body>
</html>
The more traditional way of invoking an action listener is to use a method binding, like so:
#ManagedBean
#RequestScoped
public class Login {
...
public void doLogin(ActionEvent event){
// handle action
}
}
And then in the button:
<h:commandButton id="btn_login" value="Přihlásit" actionListener="#{login.doLogin}"/>
This approach has the benefit of turning Login into a ManagedBean, which will make it so the annotations on it will be processed by JSF - and that makes the #ManagedProperty annotation work as expected.
I try to get the information about the clicked button in a <p:datalist>, but it doesn't work.
My View:
<ui:composition xmlns="http://www.w3.org/1999/xhtml"
xmlns:ui="http://java.sun.com/jsf/facelets"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:p="http://primefaces.org/ui" template="/WEB-INF/template.xhtml">
<ui:define name="head">
<title>Hash Generator</title>
</ui:define>
<ui:define name="content">
<h:form id="hashForm">
<p:dataList id="hashList" value="#{hashGeneratorBean.hashList}" var="entry" rowIndexVar="idx" itemType="none">
<p:column>
<h:outputText value="#{idx + 1}" />
<h:inputText value="#{entry.clearText}" />
<h:inputText value="#{entry.hashedText}" readonly="true" disabled="true" size="#{entry.hashedText.length() + 15}"/>
<p:commandButton id="addRow" actionListener="#{hashGeneratorBean.addRow}" icon="ui-icon-plus" title="Icon Only" update="hashList">
<f:setPropertyActionListener value="#{entry}" target="#{hashGeneratorBean.selectedRow}" />
</p:commandButton>
<p:commandButton id="debugBtn" icon="ui-icon-disc" title="Icon Only" update=":hashForm:display" oncomplete="PF('dlg').show()">
<f:setPropertyActionListener value="#{entry}" target="#{hashGeneratorBean.selectedRow}" />
</p:commandButton>
</p:column>
</p:dataList>
<p:commandButton actionListener="#{hashGeneratorBean.hash}" value="Generate Hashes" update="hashList" />
<p:dialog modal="true" widgetVar="dlg">
<h:panelGrid id="display" columns="2">
<f:facet name="header">
<h:outputText value="#{hashGeneratorBean.selectedRow.clearText}" />
</f:facet>
<h:outputText value="#{hashGeneratorBean.selectedRow.hashedText}" />
</h:panelGrid>
</p:dialog>
</h:form>
</ui:define>
</ui:composition>
My Controller:
import java.util.ArrayList;
import java.util.List;
import javax.annotation.PostConstruct;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.ViewScoped;
import javax.faces.event.ActionEvent;
import com.google.common.base.Charsets;
import com.google.common.hash.Hashing;
#ManagedBean
#ViewScoped
public class HashGeneratorBean {
private List<HashDTO> hashList = new ArrayList<HashDTO>();
private HashDTO selectedRow = new HashDTO();
#PostConstruct
public void init() {
hashList.add(new HashDTO());
}
public void addRow(ActionEvent ae){
hashList.add(new HashDTO());
}
public void hash(ActionEvent ae){
for (HashDTO entry : hashList){
entry.setHashedText(generateHash(entry.getClearText()));
}
}
/**
* Hashes the given password with SHA-256
* #param password
* #return passwordHash
*/
public static String generateHash(String password) {
return Hashing.sha256().hashString(password, Charsets.UTF_8).toString();
}
public List<HashDTO> getHashList() {
return hashList;
}
public void setHashList(List<HashDTO> hashList) {
this.hashList = hashList;
}"
public HashDTO getSelectedRow() {
return selectedRow;
}
public void setSelectedRow(HashDTO selectedRow) {
this.selectedRow = selectedRow;
}
}
If I click the "debugBtn"-button the dialog popups up and shows the correct information about the row. But If I click the "addRow"-button the data in the managed-bean isn't filled correct. The selectedRow-property allways stores the last added row from the hashList-property.
I found the solution.
The PropertyActionListener is called after the ActionListener.
the Solution is to use "Action" or register the the ActionListener with and a Extended Action Listener
I am trying to pass a parameter (a user's id from a datatable) from one page to the next where I am using it (showing the user's details). The problem is that I can not get it. What am I missing? What am I doing wrong? I am using PrimeFaces 5 and JSF 2.2 (also Hibernate 4). Is there any way that I can have the parameter #PostConstruct so that I can load the user's details immediately?
The first page with the datable
<h:form id="manageUserForm" prependId="false">
<p:growl id="messages" showDetail="true" life="20000"/>
<p:dataTable id="usersTable" var="user" value="#{manageUsers.users}">
<f:facet name="header">
#{pvtmsg.registeredUsers}
</f:facet>
<p:column headerText="ID">
<h:outputText value="#{user.id}" />
</p:column>
<p:column headerText="#{pvtmsg.username}">
<h:outputText value="#{user.username}" />
</p:column>
<p:column headerText="#{pvtmsg.firstname}">
<h:outputText value="#{user.firstname}" />
</p:column>
<p:column headerText="#{pvtmsg.lastname}">
<h:outputText value="#{user.lastname}" />
</p:column>
<p:column headerText="#{pvtmsg.email}">
<h:outputText value="#{user.email}" />
</p:column>
<p:column headerText="#{pvtmsg.status}">
<h:outputText value="#{user.enabled ? pvtmsg.enabled : pvtmsg.disabled}" />
</p:column>
<p:column style="width:32px;text-align: center">
<p:commandLink action="editUser.xhtml?faces-redirect=true">
<f:setPropertyActionListener value="#{user.id}" target="#{manageUsers.selectedUser}" />
<f:param name="userId" value="#{manageUsers.selectedUser}" />
</p:commandLink>
</p:column>
</p:dataTable>
</h:form>
Its backing bean
package beans;
import java.io.Serializable;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.faces.view.ViewScoped;
import javax.inject.Named;
import models.User;
import utils.PropertyHelper;
#Named(value = "manageUsers")
#ViewScoped
public class ManageUsers implements Serializable {
private static final long serialVersionUID = 954672295622776147L;
private List<User> users = null;
private String selectedUser = null;
public ManageUsers() {
try {
PropertyHelper helper = new PropertyHelper();
users = helper.getUsers();
} catch (Exception ex) {
Logger.getLogger(ManageUsers.class.getName()).log(Level.SEVERE, null, ex);
}
}
public List<User> getUsers() {
return users;
}
public String getSelectedUser() {
return selectedUser;
}
public void setSelectedUser(String selectedUser) {
this.selectedUser = selectedUser;
}
}
The second page
<f:metadata>
<f:viewParam name="userId" value="#{editUserBean.userId}" />
</f:metadata>
<h:form id="editUserForm" prependId="false">
<p:growl id="messages" showDetail="true" life="20000"/>
<!--nothing yet-->
</h:form>
Its backing bean
package beans;
import java.io.Serializable;
import javax.faces.view.ViewScoped;
import javax.inject.Named;
#Named(value = "editUserBean")
#ViewScoped
public class EditUserBean implements Serializable {
private static final long serialVersionUID = 543216875622776147L;
private String userId;
public String getUserId() {
return userId;
}
public void setUserId(String userId) {
this.userId = userId;
}
}
Your commandLink doesn't make sense here. Typically when you want to navigate with a commandLink, you should do a redirect in your backing bean.
If you want to navigate using outcome, then something like this should work for you:
<h:link outcome="editUser.xhtml">
<f:param name="userId" value="#{user.id}" />
</h:link>
So I found my solution here http://www.oracle.com/technetwork/articles/java/jsf22-1377252.html and, after some time, the last piece that I needed here here http://www.coderanch.com/t/625319/JSF/java/working-viewParam
Your f:viewParams won't be available during the #PostConstruct method call. You should assign a f:viewAction, since you are using JSF 2.2, to handle business processing on GET parameters.
<f:metadata>
<f:viewParam name="userId" value="#{editUserBean.userId}" />
<f:viewAction action="#{editUserBean.processUserId}"/>
</f:metadata>
See also:
Read this if using JSF older than 2.2
JSF bean: call #PostConstruct function after ViewParam is set
Sample.xhtml
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:p="http://primefaces.org/ui">
<h:head>
<f:event listener="#{sample.dosamplelist}" type="preRenderView" />
</h:head>
<h:body>
<h:form>
<h:panelGrid id="samplesetting" columns="6" cellpadding="5">
<f:facet name="header">Name Setting</f:facet>
<h:outputLabel for="samplename" value="Name:" />
<p:inputText value="#{sample.name}" id="samplename"
required="true" label="samplename" />
</h:panelGrid>
<p:panel id="sampleview" header="Sample List">
<p:dataTable var="spl" value="#{sample.samplelist}" rowKey="#{spl.name}"
selection="#{sample.selectedname}"
selectionMode="single">
<p:column headerText="Name">
<h:outputText value="#{spl.name}" />
</p:column>
<p:column>
<p:commandButton id="one" value="View Details" action="#{sample.setSelectedsample(spl)}" update="#form:samplesetting">
</p:commandButton>
</p:column>
</p:dataTable>
</p:panel>
</h:form>
Managed Bean
#SuppressWarnings("serial")
#ManagedBean(name = "sample")
#RequestScoped
public class Sample implements Serializable
{
private String name;
private List<Sample> samplelist;
private String selectedname;
//getters and setters
public void dosamplelist(ComponentSystemEvent event)
{
List<Sample> samplelist = new ArrayList<Sample>();
Sample configA = new Sample();
configA.setName("John");
samplelist.add(configA);
Sample configB = new Sample();
configB.setName("David");
samplelist.add(configB);
this.samplelist = samplelist;
}
public void setSelectedsample(Sample smpl)
{
this.name = smpl.name;
}
}
This is the sample of little big form, and the need is, when we select the table row from the bottom, it will be display to top input box for editing purpose.
But when I press the command button it do not work. why? and what is the reason please?
Possible Problem
One obvious problem is that at the class level, you've defined:
private List<Sample> samplelist;
Then you go ahead and hide the variable in doSampleList with
List<Sample> samplelist = new ArrayList<Sample>();
Combined with the fact that you have your bean marked as #RequestScoped, it will guarantee that the content of the samplelist will not be consistent during the JSF request processing.
To Solve:
Mark your bean as #ViewScoped instead and resolve the variable hiding problem as you see fit.
Further reading:
commandButton/commandLink/ajax action/listener method not invoked or input value not updated
I'm using an editable Primefaces p:datatable to show the data to the user. In this datatable, I have a p:column with a h:selectOneMenu, and another one with a p:selectBooleanCheckbox.
I want to check or uncheck and disable or enable the checkbox depending on the value selected in the h:selectOneMenu.
If I only had one h:selectOneMenu and one p:selectBooleanCheckbox, I'd use a p:ajax to attach a listener to the change event, and I'd manipulate the p:selectBooleanCheckbox in this method. But I have a pair of h:selectOneMenu and p:selectBooleanCheckbox per row and I don't know how to do this.
This is what I tried:
<h:form>
<p:dataTable var="appointment" value="#{prescController.appointmentsToday}" editable="true" id="tblAppointments">
<p:ajax event="rowEdit"
listener="#{prescController.onEdit}" update=":messages" />
<p:column sortBy="presc.drug" headerText="Drug">
<p:cellEditor>
<f:facet name="output">
<h:outputText value="#{appointment.presc.drug.name}" />
</f:facet>
<f:facet name="input">
<h:selectOneMenu value="#{appointment.presc.drug}"
converter="#{drugConverter}" required="true">
<f:selectItem itemLabel="" noSelectionOption="true" />
<f:selectItems value="#{prescController.drugs}"
var="drug" itemLabel="#{drug.name}" />
<p:ajax update="autoAmount" />
</h:selectOneMenu>
</f:facet>
</p:cellEditor>
</p:column>
<p:column sortBy="presc.autoAmount" headerText="Auto amount">
<p:cellEditor>
<f:facet name="output">
<h:outputText value="Y"
rendered="#{not empty appointment.presc.drug.rules and appointment.presc.autoAmount}" />
<h:outputText value="N"
rendered="#{empty appointment.presc.drug.rules or not appointment.presc.autoAmount}" />
</f:facet>
<f:facet name="input">
<p:selectBooleanCheckbox id="autoAmount"
value="#{not empty appointment.presc.drug.rules and appointment.presc.autoAmount}"
disabled="#{appointment.presc.drug.name eq 'somethingsomething'}" />
</f:facet>
</p:cellEditor>
</p:column>
<p:column>
<p:rowEditor />
</p:column>
</p:dataTable>
</h:form>
The post Retrieving other component's client ID in JSF 2.0 describes how to retrieve ids of other components in a page. In my opinion, the #{p:component('sampleButton')} should find the next component having this ID in the component tree - this should be the same row.
Alternatively, you should be able to rerender the whole row via JSF 2 #{component.parent.clientId} functionality (measure out, how many "parent" steps you need, e.g. #{component.parent.parent.clientId}).
Hope it helps, else just add comments... :-)
I can't imagine why you are unsatisfied with simple update="checkboxId"but what you can try is updating component through widgetVar which you can generate during page render.
Tiny example:
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:h="http://xmlns.jcp.org/jsf/html" xmlns:p="http://primefaces.org/ui">
<h:head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>Table Example</title>
</h:head>
<h:body>
<h:form prependId="false">
<p:dataTable var="data" value="#{tableBean.data}">
<p:column headerText="Command">
<p:commandButton value="Toggle" actionListener="#{tableBean.toggleSelection(data.id)}"
update="#widgetVar(tableCheckboxComponent_#{data.id})" />
</p:column>
<p:column headerText="Value">
<h:outputText value="#{data.value}" />
</p:column>
<p:column headerText="Selected">
<p:selectBooleanCheckbox widgetVar="tableCheckboxComponent_#{data.id}" value="#{data.selected}" />
</p:column>
</p:dataTable>
</h:form>
</h:body>
</html>
Backing bean:
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.ViewScoped;
#ManagedBean
#ViewScoped
public class TableBean {
private Map<String, MyData> data;
public List<MyData> getData(){
return new ArrayList<MyData>(data.values());
}
public TableBean() {
data = new HashMap<String, MyData>();
for (int i = 0; i<22; i++) {
String id = "id" + Integer.toString(i);
data.put(id, new MyData( id , i));
}
}
public void toggleSelection(String id) {
MyData myData = data.get(id);
myData.setSelected(!myData.isSelected());
}
}
And Data object:
public class MyData {
private String id;
private boolean selected;
private int value;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public int getValue() {
return value;
}
public void setValue(int value) {
this.value = value;
}
public boolean isSelected() {
return selected;
}
public void setSelected(boolean selected) {
this.selected = selected;
}
public MyData(String id, int value) {
this.id = id;
this.value = value;
this.selected = false;
}
}
I still don't know why my approach didn't work.
In the end, I added a listener to the p:ajax component to manipulate the SelectBooleanCheckbox in the managed bean
<p:ajax listener="#{prescBean.onDrugSelected}" update="autoAmount" />
public void onDrugSelected(AjaxBehaviorEvent event) {
Drug drug = (Drug) ((UIOutput) event
.getSource()).getValue();
boolean hasRules = drug.getRules().size() > 0;
SelectBooleanCheckbox cbAutoAmount = (SelectBooleanCheckbox) ComponentUtils
.findComponent(FacesContext.getCurrentInstance().getViewRoot(),
"autoAmount");
cbAutoAmount.setDisabled(!hasRules);
cbAutoAmount.setValue(hasRules);
}