does not set the expected value based on

Question

I have written a code like this:

<ui:repeat var="fstDayWk" value="#{calendarBean.date}">
        <c:choose>
            <c:when test="#{fstDayWk == 'Sun'}">
                <c:set var="fstDayWk" value="7"/>
            </c:when>

            <c:when test="#{fstDayWk =='Mon'}">
                <c:set var="fstDayWk" value="1" />
            </c:when>

            <c:when test="#{fstDayWk =='Tue'}">
                <c:set var="fstDayWk" value="2" />
            </c:when>

            <c:when test="#{fstDayWk =='Wed'}">
                <c:set var="fstDayWk" value="3" />
            </c:when>

            <c:when test="#{fstDayWk =='Thu'}">
                <c:set var="fstDayWk" value="4" />
            </c:when>

            <c:when test="#{fstDayWk =='Fri'}">
                <c:set var="fstDayWk" value="5" />
            </c:when>

            <c:when test="#{fstDayWk =='Sat'}">
                <c:set var="fstDayWk" value="6"/>
            </c:when>
            <c:otherwise>
                <c:set var="fstDayWk" value="1" />
            </c:otherwise>
        </c:choose>
</ui:repeat>

But here the value assignment for fstDayWk is always 1. Why so? How could I set value to some variable depending upon some condition in JSF?

Answer 1

JSTL tags runs during view build time, when the JSF component tree is about to be built/constructed based on JSF tags in the XHTML file. JSF components such as <ui:repeat> in turn runs during view render time, when the built JSF component tree is about to produce HTML code.

So, <c:choose> and <ui:repeat> does not run in sync as you seemed to expect from the coding. In fact, it's first the <c:choose> which runs during view build time and then it's the <ui:repeat> which runs during view render time. At that moment when <c:choose> runs, the #{fstDayWk} which is supposed to be set by <ui:repeat> is not available anywhere in the EL scope and thus the <c:choose> always ends up in the <c:otherwise> condition.

It will work if you use <c:forEach> instead of <ui:repeat>. However, much better would be to use a Map<String, Integer> in the model which maintains a mapping between day of week and its index, so that you don't need the whole ugly <c:choose> block anymore.

See also:

• JSTL in JSF2 Facelets... makes sense?