JSF composite component with backing bean

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.