How to display my application's errors in JSF?

Solution 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;
    }
}

Solution 2:

In case anyone was curious, I was able to figure this out based on all of your responses combined!

This is in the Facelet:

<h:form id="myform">
  <h:inputSecret value="#{createNewPassword.newPassword1}" id="newPassword1" />
  <h:message class="error" for="newPassword1" id="newPassword1Error" />
  <h:inputSecret value="#{createNewPassword.newPassword2}" id="newPassword2" />
  <h:message class="error" for="newPassword2" id="newPassword2Error" />
  <h:commandButton value="Continue" action="#{createNewPassword.continueButton}" />
</h:form>

This is in the continueButton() method:

FacesContext.getCurrentInstance().addMessage("myForm:newPassword1", new FacesMessage(PASSWORDS_DONT_MATCH, PASSWORDS_DONT_MATCH));

And it works! Thanks for the help!

Solution 3:

You also have to include the FormID in your call to addMessage().

 FacesContext.getCurrentInstance().addMessage("myform:newPassword1", new FacesMessage("Error: Your password is NOT strong enough."));

This should do the trick.

Regards.

Solution 4:

Remember that:

FacesContext context = FacesContext.getCurrentInstance();
context.addMessage( null, new FacesMessage( "The message to display in client" ));

is also valid, because when null is specified as first parameter, it is applied to the whole form.

More info: coreservlets.com //Outdated

Solution 5:

JSF is a beast. I may be missing something, but I used to solve similar problems by saving the desired message to a property of the bean, and then displaying the property via an outputText:

<h:outputText
    value="#{CreateNewPasswordBean.errorMessage}"
    render="#{CreateNewPasswordBean.errorMessage != null}" />