Exemplifying <c:if> versus <ui:fragment>

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A common scenario is to render a table data based on a <c:if> condition, as follows:

<h:dataTable value="#{playersBean.dataArrayList}" var="t">

 <h:column>

  <c:if test="#{t.age gt 26}">

   <h:outputText value="#{t.player}, #{t.age}"/>

  </c:if>

 </h:column>

</h:dataTable>

Well, the result will not be as expected. The problem is that <c:if> is a tag handler; therefore, it is efficiently reflected when the tree is built. A perfect workaround will be to replace <c:if> with the <ui:fragment> tag, which is a component handler. The rendered attribute of <ui:fragment> can successfully replace the <c:if> test using the following code:

<h:dataTable value="#{playersBean.dataArrayList}" var="t">

 <h:column>

  <ui:fragment rendered="#{t.age gt 26}">

   <h:outputText value="#{t.player}, #{t.age}"/>

  </ui:fragment>

 </h:column>

</h:dataTable>

Alternatively, in an even simpler way, use the rendered attribute of <h:outputText>; this approach is particular to this example:

<h:dataTable value="#{playersBean.dataArrayList}" var="t">

 <h:column>

  <h:outputText value="#{t.player}, #{t.age}" rendered="#{t.age gt 26}"/>

 </h:column>

</h:dataTable>

Instead, even cooler, using a lambda expression (EL 3.0), you can write the following code:

<h:dataTable value="#{(playersBean.dataArrayList.stream().filter((p)->p.age gt 26 )).toList()}" var="t">

 <h:column>

  <h:outputText value="#{t.player}, #{t.age}"/>

 </h:column>

</h:dataTable>

Is very possible that lambda expression can help you to easily choose when and what to render.

More X vs Y posts onZEEF page, and in Mastering JavaServer Faces 2.2.