How to display my application's errors in JSF?

Question

In my JSF/Facelets app, here's a simplified version of part of my form:

<h:form id="myform">
  <h:inputSecret value="#{createNewPassword.newPassword1}" id="newPassword1" />
  <h:message class="error" for="newPassword1" />
  <h:inputSecret value="#{createNewPassword.newPassword2}" id="newPassword2" />
  <h:message class="error" for="newPassword2" />
  <h:commandButton value="Continue" action="#{createNewPassword.continueButton}" />
</h:form>

I'd like to be able to assign an error to a specific h:message tag based on something happening in the continueButton() method. Different errors need to be displayed for newPassword and newPassword2. A validator won't really work, because the method that will deliver results (from the DB) is run in the continueButton() method, and is too expensive to run twice.

I can't use the h:messages tag because the page has multiple places that I need to display different error messages. When I tried this, the page displayed duplicates of every message.

I tried this as a best guess, but no luck:

public Navigation continueButton() {
  ...
  expensiveMethod();
  if(...) {
    FacesContext.getCurrentInstance().addMessage("newPassword", new FacesMessage("Error: Your password is NOT strong enough."));
  }
}

What am I missing? Any help would be appreciated!

Answer 1

FacesContext.addMessage(String, FacesMessage) requires the component's clientId, not it's id. If you're wondering why, think about having a control as a child of a dataTable, stamping out different values with the same control for each row - it would be possible to have a different message printed for each row. The id is always the same; the clientId is unique per row.

So "myform:mybutton" is the correct value, but hard-coding this is ill-advised. A lookup would create less coupling between the view and the business logic and would be an approach that works in more restrictive environments like portlets.

<f:view>
  <h:form>
    <h:commandButton id="mybutton" value="click"
      binding="#{showMessageAction.mybutton}"
      action="#{showMessageAction.validatePassword}" />
    <h:message for="mybutton" />
  </h:form>
</f:view>

Managed bean logic:

/** Must be request scope for binding */
public class ShowMessageAction {

    private UIComponent mybutton;

    private boolean isOK = false;

    public String validatePassword() {
        if (isOK) {
            return "ok";
        }
        else {
            // invalid
            FacesMessage message = new FacesMessage("Invalid password length");
            FacesContext context = FacesContext.getCurrentInstance();
            context.addMessage(mybutton.getClientId(context), message);
        }
        return null;
    }

    public void setMybutton(UIComponent mybutton) {
        this.mybutton = mybutton;
    }

    public UIComponent getMybutton() {
        return mybutton;
    }
}