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JSTL forEach tag: problems with enumeration, and with understanding how it should work

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+4 A:

This article explains the difference between the unified EL and the EL. Here is a snippet

Evaluation of EL

Evaluation of EL is categorized as immediate evaluation and deferred evaluation. Immediate evaluation means a JSP page evaluates the expression when the page is rendered. With immediate evaluation, all values are always read-only. JSP EL expressions take the form of ${imExpr}. JSP expressions are evaluated immediately.

Deferred evaluation means that the technology using the unified EL takes over the responsibility of evaluating the expression from the JSP engine and evaluates the expression at the appropriate time during the page lifecycle. The EL takes control from the JSP container to evaluate the expression at the appropriate time. JSF EL expressions take the form of #{defExpr}. JSF expressions work in this way.

The following example shows a JSF inputText tag, which represents a text field component into which a user enters a value. The inputText tag's value attribute references an expression that points to the name property of the book bean.

<h:inputText id="name" value="#{student.name}"/>

For an initial request of the page containing this tag, the JSF implementation evaluates the #{student.name} expression during the "render response" phase of the lifecycle. During this phase, the expression merely accesses the value of quantity from the book bean, as is done in immediate evaluation.

For a postback, the implementation evaluates the expression during the "apply request values," "process validations," and "update model" phases, during which the value is retrieved from the request, validated, and propagated to the book bean.

I am wondering if the problem is from the fact that an instance of SessionBean was not created?

Try this:

<jsp:useBean class="packagename.SessionBean" id="sb"/>
<c:forEach var="myObject" items="${sb.objects}">
            <h:outputText value="${myObject}" /> <br />
</c:forEach>

[Update] I wonder if this article might help then. It explains how the two EL's work together.

Vincent Ramdhanie 2008-11-02 14:24:15

Thanks, updated the question that SessionBean was created.

AnSGri 2008-11-02 14:29:56

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JSTL forEach tag: problems with enumeration, and with understanding how it should work

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