FacesContext can't display error msg !

Question

Hi guys,
I got this problem. For this function:
     public User saveUser(User user) throws DBException {
          try {
               User newUser = this.userDao.saveUser(user);
               return newUser;
          } catch (DataIntegrityViolationException di) {
               String msg = "duplicate user id";
               this.logger.error(msg, de);
               throw new DuplicateUserIdException(msg);
=======================================
then the below function is to execute when user click the submit button
public String submitAction() {.....
catch (DuplicateUserIdException de) {
String msg = "Username already exists";
this.logger.info(msg);
FacesContext.getCurrentInstance().addMessage(null, new FacesMessage( FacesMessage.SEVERITY_INFO, msg, msg));
return QueryResults.RETRY;
========================================
public class DuplicateUserIdException extends DBException {
     private String username;
     public DuplicateUserIdException(String newUsername) {     
          super("Username " + newUsername + " already exist");
          this.username = newUsername;
     public String getUsername() {
          return this.username;
====================================
So when I click on the submit button after entering a duplicate username, it will just go back to the same page and no error message display. Username is a primary key and email address is set to UNIQUE in MySQL DB. I read the log file and indeed all the error messages can be catched. The registration.jsp page is like:
<h:inputText value="#{userBean.username}" id="username" required="true">
<f:validateLength maximum="20" minimum="5"/>
</h:inputText>
<h:message for="username"/>
but I got my login page also the same h:inputText as above.
I am using JSF + Spring + Hibernate.
I hv tried to fix it a few time but failed !
Appreciate any help here.

Answer 1

K> then the below function is to execute when user click
K> the submit button
K>
K> public String submitAction() {.....
K>
K> catch (DuplicateUserIdException de) {
K> String msg = "Username already exists";
K> this.logger.info(msg);
K> FacesContext.getCurrentInstance().addMessage(null,
K> l, new FacesMessage( FacesMessage.SEVERITY_INFO,
K> msg, msg));
K> return QueryResults.RETRY;
K>           }
K> }
K> So when I click on the submit button after entering a
K> duplicate username, it will just go back to the same
K> page and no error message display. Username is a
K> primary key and email address is set to UNIQUE in
K> MySQL DB. I read the log file and indeed all the
K> error messages can be catched. The registration.jsp
K> page is like:
K>
K> <h:inputText value="#{userBean.username}"
K> id="username" required="true">
K> <f:validateLength maximum="20" minimum="5"/>
K> </h:inputText>
K> <h:message for="username"/>
K>
K> but I got my login page also the same h:inputText as
K> above.
K>
K> I am using JSF + Spring + Hibernate.
K>
K> I hv tried to fix it a few time but failed !
K> Appreciate any help here.
Ok, we have to keep in mind the request processing lifecycle here. Your
submitAction() method is called after conversion and validation have
already occurred. Therefore, you can never queue an error from an
action handler. Here's why.
When your submitAction() is called, you queue a message into the faces
context. Whatever you return from submitAction(), it's ultimately going
to cause a requestDispatcher.forward() or
httpServletRespones.sendRedirect(). Both of these cause a new
FacesContext instance to be created, obliterating your carefully queued
message.
The best practice I've seen used is to handle the validation as close to
the component in which the validation error occured as possible. I
recommend creating a custom validator method binding, that does the
trick. This is really easy to do. Just add a method to your bean:
public void validate(FacesContext context,
UIComponent component,
Object value) throws ValidatorException {
// queue the message here, make sure to call component.setValid(false)
Then, in your inputText, you say:
<h:inputText value="#{userBean.username}" validator="#{userBean.validate}
id="username" required="true">
<f:validateLength maximum="20" minimum="5"/>
</h:inputText>
And you're done.
Ed (JSR-252 Spec co-lead)