Add message and stay on form after clicking commandButton - forms

Question

I have a form with some fields that are validated while processing the form data. It's a kind of a plausibility / consistency check. The check itself is costly, so it should not be performed twice. But it must be performed during successful form submission, so it's part of the commandButton's action method in the backing bean.
I think if I use a <f:validator>, it will be performed once for the validation phase and then once again when submission takes place. As I said, that's not desirable.
As far as I understand the docs, it should be sufficient to add a message to one of the form's components in order to stay on the form.
So I've tried
FacesContext.getCurrentInstance().addMessage("comandButtonID", "some message");
but it does not stay on the form.
Do I need to do something additional to mark the form as invalid ?
If it matters, the backing bean is request-scoped.
So, here comes the minimal complete example.
OS: Linux
Browser: Chromium
Server: Tomcat 8.0.36
JDK: Oracle-JDK 1.8.0_92
JSF implementation: myfaces 2.1.18 + tomahawk 20-1.1.14
There is one thing I found out during creating this example:
When I set javax.faces.PROJECT_STAGE to "Development" and facelets.DEVELOPMENT to "true", and the message is displayed.
With the settings grom the web.xml below, it's not.
web.xml (omitted descriptions)
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
version="3.0">
<context-param>
<param-name>javax.faces.DEFAULT_SUFFIX</param-name>
<param-value>.xhtml</param-value>
</context-param>
<context-param>
<param-name>facelets.REFRESH_PERIOD</param-name>
<param-value>2</param-value>
</context-param>
<context-param>
<param-name>facelets.SKIP_COMMENTS</param-name>
<param-value>true</param-value>
</context-param>
<context-param>
<param-name>javax.faces.PROJECT_STAGE</param-name>
<param-value>Production</param-value>
</context-param>
<context-param>
<param-name>facelets.DEVELOPMENT</param-name>
<param-value>false</param-value>
</context-param>
<context-param>
<param-name>javax.faces.STATE_SAVING_METHOD</param-name>
<param-value>server</param-value>
</context-param>
<context-param>
<param-name>
org.apache.myfaces.NUMBER_OF_VIEWS_IN_SESSION
</param-name>
<param-value>20</param-value>
</context-param>
<!-- START MyFaces filter -->
<filter>
<filter-name>MyFacesExtensionsFilter</filter-name>
<filter-class>
org.apache.myfaces.webapp.filter.ExtensionsFilter
</filter-class>
<init-param>
<param-name>uploadMaxFileSize</param-name>
<param-value>100m</param-value>
</init-param>
<init-param>
<param-name>uploadThresholdSize</param-name>
<param-value>100k</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>MyFacesExtensionsFilter</filter-name>
<servlet-name>Faces Servlet</servlet-name>
</filter-mapping>
<filter-mapping>
<filter-name>MyFacesExtensionsFilter</filter-name>
<url-pattern>/faces/myFacesExtensionResource/*</url-pattern>
</filter-mapping>
<filter-mapping>
<filter-name>MyFacesExtensionsFilter</filter-name>
<url-pattern>*.xhtml</url-pattern>
</filter-mapping>
<filter-mapping>
<filter-name>MyFacesExtensionsFilter</filter-name>
<url-pattern>/faces/*</url-pattern>
</filter-mapping>
<!-- END MyFaces filter -->
<!-- START MyFaces config -->
<context-param>
<param-name>org.apache.myfaces.SERIALIZE_STATE_IN_SESSION</param-name>
<param-value>false</param-value>
</context-param>
<context-param>
<param-name>org.apache.myfaces.PRETTY_HTML</param-name>
<param-value>true</param-value>
</context-param>
<context-param>
<param-name>org.apache.myfaces.ALLOW_JAVASCRIPT</param-name>
<param-value>true</param-value>
</context-param>
<context-param>
<param-name>org.apache.myfaces.DETECT_JAVASCRIPT</param-name>
<param-value>false</param-value>
</context-param>
<context-param>
<param-name>
org.apache.myfaces.READONLY_AS_DISABLED_FOR_SELECTS
</param-name>
<param-value>true</param-value>
</context-param>
<context-param>
<param-name>org.apache.myfaces.AUTO_SCROLL</param-name>
<param-value>false</param-value>
</context-param>
<context-param>
<param-name>
org.apache.myfaces.CHECK_EXTENSIONS_FILTER
</param-name>
<param-value>true</param-value>
</context-param>
<context-param>
<param-name>org.apache.myfaces.ADD_RESOURCE_CLASS</param-name>
<param-value>
org.apache.myfaces.renderkit.html.util.DefaultAddResource
</param-value>
</context-param>
<context-param>
<param-name>
org.apache.myfaces.RESOURCE_VIRTUAL_PATH
</param-name>
<param-value>/faces/myFacesExtensionResource</param-value>
</context-param>
<servlet>
<servlet-name>Faces Servlet</servlet-name>
<servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>Faces Servlet</servlet-name>
<url-pattern>*.xhtml</url-pattern>
</servlet-mapping>
<!-- END MyFaces config -->
<welcome-file-list>
<welcome-file>testform.xhtml</welcome-file>
</welcome-file-list>
</web-app>
faces-config.xml
<?xml version='1.0' encoding='UTF-8'?>
<faces-config xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-facesconfig_2_0.xsd"
version="2.0">
<managed-bean>
<managed-bean-name>FormTest</managed-bean-name>
<managed-bean-class>FormTest</managed-bean-class>
<managed-bean-scope>request</managed-bean-scope>
</managed-bean>
<navigation-rule>
<navigation-case>
<from-action>#{FormTest.formAction}</from-action>
<from-outcome>OK</from-outcome>
<to-view-id>/testform_OK.xhtml</to-view-id>
</navigation-case>
<!-- I've also tried to remove the second navigation-case -->
<navigation-case>
<from-action>#{FormTest.formAction}</from-action>
<from-outcome>FAIL</from-outcome>
<to-view-id>/testform.xhtml</to-view-id>
</navigation-case>
</navigation-rule>
</faces-config>
FormTest.java
public class FormTest {
String input;
public String getInput() {
return input;
}
public void setInput(String input) {
this.input = input;
}
public String formAction() {
final boolean valid = "ok".equalsIgnoreCase(input);
if (!valid) {
final FacesMessage message = new FacesMessage("not OK");
message.setSeverity(FacesMessage.SEVERITY_ERROR);
FacesContext.getCurrentInstance().addMessage("submit", message);
}
return valid ? "OK" : "FAIL";
}
}
testform.xhtml
<?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://java.sun.com/jsf/html"
xmlns:t="http://myfaces.apache.org/tomahawk">
<h:head>
<title>Test Form</title>
</h:head>
<h:body>
<h:form id="form">
<h:outputText value="Enter "ok" (case insensitive) to get to the next page."/>
<br/>
<h:outputText value="Any other value should give an error message and stay on this page."/>
<br/>
<h:inputText id="input" value="#{FormTest.input}"/>
<br/>
<h:message id="submitMessage" for="submit"/>
<t:commandButton id="submit" value="Submit" action="#{FormTest.formAction}"/>
</h:form>
</h:body>
</html>
testform_OK.xhtml
<!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">
<h:head>
<title>Form was submitted</title>
</h:head>
<h:body>
Form was submitted with value "OK".
</h:body>
</html>