jsp (jstl 1.2) - set a variable from a java list

Question

(I am using jstl version 1.2 and java 6)

I am working with some legacy code that has some logic in its jsp pages, that aside I now need to loop over a list of data, match on something and then set a variable to list value (ArrayList in this case). The reason I need to do this is to then loop over the list I found later on in the jsp file.

Here is the snippet of code I have so far, but does not work:

  <c:set var="listOfChildData" value="${[]}" scope="page"/>

  <c:forEach items="${otherListOfData}" var="data">

    <c:if test="${data.id == dataToMatchOn.id}">

      <c:catch var="exception">${data.children}</c:catch>
      <c:if test="${empty exception}">

        <c:set var="listOfChildData" value="${data.children.toArray()}" scope="page"/>

      </c:if>
    </c:if>
  </c:forEach>

Do I need to manually go through each item in the list and add it to the listOfChildData ?

Reading around, all the examples I found were of creating an array variable from scratch and not from another variable.

If this comes down to using scriptlets, can I do that within a forEach loop?

---

Updated to include exception handling if data.children is null, empty, etc.

Answer 1

You don't need to copy the list. All you need to set is the selectedItem and then you can work with this:

<c:forEach items="${otherListOfData}" var="data">
    <c:if test="${data.id == dataToMatchOn.id}">
        <c:set var="selectedItem" value="${data}/>
    </c:if>
</c:forEach>

<p>From here on I can work with the selected item:</p>

${selectedItem.children}