JSF composite component with backing bean - jsf

Question

I'm trying to get a composite component working with it's own backing bean,
using the example on p375 from the Core JSF 3 book, but just get an NPE. The problem seems to be at the start of encodeBegin(), Date date = (Date) getValue() returns null.
If I'm honest I don't really understand where the value of the component is supposed to
be getting stored, I specify it as a java.util.Date using cc:attribute type=, but I
don't really understand how this: public Object getSubmittedValue() { return this; } -
which is going to return an instance of an InputDateBean class - results in a Date. I am generally good and confused by how this is supposed to work.
Unlike the book example I am trying to the use backing component for temporary storage,
so when the day is input I try to store it in #{cc.day}, in the book they use an application scoped bean for some reason.
Thanks for any help. I am using Mojarra 2.1.
inputDate.xhtml
<cc:interface componentType="uk.co.myco.jsfbeans.sqcc.InputDateBean">
<cc:attribute name="value" type="java.util.Date"/>
</cc:interface>
<cc:implementation>
<h:panelGrid columns="3">
<h:inputText id="day" value="#{cc.day}"
converter="javax.faces.Integer"/>
<h:inputText id="month" value="#{cc.month}"
converter="javax.faces.Integer"/>
<h:inputText id="year" value="#{cc.year}"
converter="javax.faces.Integer"/>
</h:panelGrid>
</cc:implementation>
InputDateBean.java
package uk.co.myco.jsfbeans.sqcc;
import java.io.IOException;
import java.util.Calendar;
import java.util.Date;
import javax.faces.component.FacesComponent;
import java.util.GregorianCalendar;
import javax.faces.application.FacesMessage;
import javax.faces.component.NamingContainer;
import javax.faces.component.UIInput;
import javax.faces.context.FacesContext;
import javax.faces.convert.ConverterException;
import uk.co.myco.general.SQLog;
import uk.co.myco.jsfbeans.helper.Messages;
#FacesComponent(value = "uk.co.myco.jsfbeans.sqcc.InputDateBean")
public class InputDateBean extends UIInput implements NamingContainer {
private int day = 0, month = 0, year = 0;
public InputDateBean() {
}
#Override
public String getFamily() {
return "javax.faces.NamingContainer";
}
#Override
public void encodeBegin(FacesContext context) throws IOException {
Date date = (Date) getValue();
Calendar cal = new GregorianCalendar();
cal.setTime(date);
UIInput dayComponent = (UIInput) findComponent("day");
UIInput monthComponent = (UIInput) findComponent("month");
UIInput yearComponent = (UIInput) findComponent("year");
dayComponent.setValue(cal.get(Calendar.DATE));
monthComponent.setValue(cal.get(Calendar.MONTH) + 1);
yearComponent.setValue(cal.get(Calendar.YEAR));
super.encodeBegin(context);
}
#Override
public Object getSubmittedValue() {
return this;
}
#Override
protected Object getConvertedValue(FacesContext context, Object newSubmittedValue)
throws ConverterException {
UIInput dayComponent = (UIInput) findComponent("day");
UIInput monthComponent = (UIInput) findComponent("month");
UIInput yearComponent = (UIInput) findComponent("year");
int lday = (Integer) dayComponent.getValue();
int lmonth = (Integer) monthComponent.getValue();
int lyear = (Integer) yearComponent.getValue();
if (isValidDate(lday, lmonth, lyear)) {
return new GregorianCalendar(lyear, lmonth - 1, lday).getTime();
} else {
FacesMessage message = Messages.getMessage("util.messages", "invalidDate", null);
message.setSeverity(FacesMessage.SEVERITY_ERROR);
throw new ConverterException(message);
}
}
// getters & setters & isValidDate() removed
}

Answer 1

I now see my mistake. The problem was that the composite component has to be
called with a Date object, i.e. <cclib:inputDate value="#{bean.date}"/>. As the
code stands the date needs to be instantiated, but it wasn't. The more robust
way of doing this is to do a new Date() in encodeBegin() in the event that
getValue() is null. This then works the same a h:inputText/f:convertDateTime
which does not require that the value is instantiated.