Question

I am working on a custom tag that processes a hierarchical Bean. The bean looks something like this:

public class HierarchyBean {
    public List<HierarchyBean> children;
    public List<SomeOtherBean> someListOfBeans;
    // getters/setters for Bean
}

Now I want to make a tag such that I could do this in my JSP:

<ul>
<cust:hierarchy hierarchyBean="${root}">
    <li>${subBean}</li>
</cust:hierarchy>
</ul>

with the custom tag looking something like this:

<%@ tag body-content="scriptless" %>

<%@ attribute name="hierarchyBean" required="true" rtexprvalue="true" type="com.publix.webforms3.survey.domain.Element" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"  %>
<%@ taglib uri="http://www.springframework.org/tags" prefix="spring" %>
<%@ taglib uri="http://www.springframework.org/tags/form" prefix="form" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/functions" prefix="fn" %>
<%@ taglib prefix="cust" tagdir="/WEB-INF/tags/hierarchy" %>

<c:forEach items="${someListOfBeans}" var="bean">
    <c:set var="subBean" value="${bean}" scope="page" />
    <jsp:doBody />
</forEach>
<ul>
<c:forEach items="${children}" var="child">
<cust:hierarchy hierarchyBean="${root}">
    <li>${subBean}</li>
</cust:hierarchy>
</c:forEach>
</ul>

So, first, let me appologize if there are sloppy mistakes in the above code…my actual project is quite complex, and I tried to hand-type a more simple example.

Second, I’d like to point out the recursive nature of the tag IS working. What is not working is the setting of “subBean”. I tried both with and without the c:set, but in my calling JSP code it appears that subBean is not carried out of the tag back to the body within the tag.

I do know that the jsp:doBody has some attributes, namely var and varReader, but it doesn’t seem like either is doing what I need.

Is this possible, and if so, what am I doing wrong here that is making it not work?

Answer 1

You should add the following to your tag:

<%@ variable name-given="subBean" scope="NESTED" %>

This will cause the container to save the value of the subBean attribute in the page (if any), then invoke your tag and make the subBean variable defined by the tag available to the body of the tag, then restore the saved value of the subBean attribute.

More details here.