EL expression in c:choose, can't get it working

Question

I'm trying something (JSF2) like this:

<p>#{projectPageBean.availableMethods}</p>
<c:choose>
  <c:when test="${projectPageBean.availableMethods == true}">
    <p>Abc</p>
  </c:when>
  <c:otherwise>
    <p>Xyz</p>
  </c:otherwise>
</c:choose>

But this doesn't seem to work, although the EL expression in the top paragraph changes from false to true, the next paragraph always shows Xyz?

I also tried to change the test to:

${projectPageBean.availableMethods}

But still the same problem!

Thanks! The fraction is within , , , and finally a tag! – g.verhaag Jun 20 '13 at 16:18 — g.verhaag, Jun 20 '13 at 16:18
My answer is also applicable to ``. – BalusC Jun 20 '13 at 17:27 — BalusC, Jun 20 '13 at 17:27

score 2 · Accepted Answer · edited Jun 20 '20 at 09:12

First and foremost: JSTL tags runs during view build time, not during view render time.

Your concrete problem suggests that #{projectPageBean} is been set during view render time, such as would happen when definied as <ui:repeat var>, <h:dataTable var>, <p:tabView var>, etc. It's thus null during view build time.

In that case, you should not be using a view build time tag to conditionally render HTML. You should instead use a view render time component to conditionally render HTML. As first choice, use <ui:fragment>:

<p>#{projectPageBean.availableMethods}</p>
<ui:fragment rendered="#{projectPageBean.availableMethods}">
    <p>Abc</p>
</ui:fragment>
<ui:fragment rendered="#{not projectPageBean.availableMethods}">
    <p>Xyz</p>
</ui:fragment>

By the way, there's in Facelets no need to switch between #{} and ${}. In contrary to JSP, in Facelets the ${} behaves exactly the same as #{}. To avoid potential confusion and maintenance trouble, I recommend to stick to #{} all the time.

EL expression in c:choose, can't get it working

1 Answers1

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