Value remains in form field after it is cleared in bean in JSF2 - validation

Question

In my JSF2 application, I have "Clear" button, which is supposed to clear all the fields. However, it doesn't always work.
My page fragment:
<h:form id="bi">
<h:inputText value="#{bean.entity.firstname}" />
<h:inputText value="#{bean.entity.surname}" />
<h:commandButton value="Clear" immediate="true" action="#{bean.clear}">
<f:ajax render="bi" />
</h:commandButton>
<h:commandButton value="Submit" action="#{bean.submit}" />
</h:form>
And clear() method in my bean:
public void clear() {
entity = new Entity();
}
If I enter values in the fields, and click "Clear", everything is cleared as expected. However, consider such scenario:
1. Enter value only in one field (both are required by JSR303 annotations on entity).
2. Click "Submit". Error message appears.
3. Click "Clear".
Entered value remains. Why is it not cleared?
Moreover, if I clear it by hand, and click "Clear", it returns to the field. I checked that it comes to the browser in partial response after clicking "Clear" button. I suspect it has something to do with view state.
Moreover, if I add validator="#{bean.validate}" to the field, it enter this validation. Even if button has immediate="true" attribute. Why? Shouldn't immediate button ommit validation?

Answer 1

You've run into a more or less well-known issue regarding updating components for which validation has already happened.
This post is rather old, but still relevant: http://ishabalov.blogspot.com/2007/08/sad-story-about-uiinput.html
There is a community created solution for A4J in JSF 1.2 posted here: http://community.jboss.org/thread/8446?start=15&tstart=0
But unfortunately, this doesn't work directly in JSF 2.0 and in your case it wouldn't work at all since it's A4J specific. Nevertheless it might be a source of inspiration.
Basically you need to walk the component tree and clear its state. The neatest thing is to clear exactly the state of the components that you are going to re-render. But you might take the brute-force approach and just clear all if your particular application or page can tolerate that.

Answer 2

I wound up having to avoid submit or action to get the form to clear properly. I used actionListener with a void bean method instead.
But then I faced the problem of conditionally needing navigation which is usually done with a String method from action. I used ExternalContext.redirect() to accomplish that which I learned from the following:
JSF PostConstruct Exception Handling - Redirect
JSF navigation redirect to previous page
my page code:
<p:commandButton value="Login" update=":loginForm"
actionListener="#{loginBean.login}"/>
my bean code:
public void login() {
RtsLDAPAD laLdap = new RtsLDAPAD();
boolean lbAuthenticated = false;
try
{
lbAuthenticated = laLdap.login(userName, password);
System.out.println(
"The Result is " + lbAuthenticated + " for " + userName);
}
catch (Exception aeRTSEx)
{
aeRTSEx.printStackTrace();
}
if (lbAuthenticated) {
try {
FacesContext.getCurrentInstance().getExternalContext().redirect("taskform.jsf");
} catch (IOException e) {
e.printStackTrace();
}
} else {
FacesContext facesContext = FacesContext.getCurrentInstance();
facesContext.addMessage(null,
new FacesMessage("Login failed for " + userName + "."));
UIViewRoot uiViewRoot = facesContext.getViewRoot();
HtmlInputText inputText = null;
Password pwd = null;
inputText = (HtmlInputText) uiViewRoot.findComponent("loginForm:username");
inputText.setSubmittedValue(null);
inputText.setValue(null);
inputText.setLocalValueSet(false);
inputText.setValid(true);
pwd = (Password) uiViewRoot.findComponent("loginForm:password");
pwd.setSubmittedValue(null);
pwd.setValue(null);
pwd.setLocalValueSet(false);
pwd.setValid(true);
userName = null;
password = null;
}
}