jstl foreach omit an element in last record

Question

trying to use this jstl to formulate a json string, how can i make the segment not to put a comma in the end of the last record? note the comma in the end

<c:forEach items="${fileList}" var="current">
    { id:1001,data:["<c:out value="${current.fileName}" />" , "<c:out value="${current.path}" />" , "<c:out value="${current.size}" />" , "<c:out value="${current.type}" />"] },
</c:forEach>

all elements need the } but the last must not have the comma , — nokheat, Jun 23 '10 at 06:06

score 171 · Accepted Answer · answered Jun 23 '10 at 11:58

Just use LoopTagStatus#isLast().

<c:forEach items="${fileList}" var="current" varStatus="loop">
    { id: 1001,
      data: [
        "<c:out value="${current.fileName}" />",
        "<c:out value="${current.path}" />",
        "<c:out value="${current.size}" />",
        "<c:out value="${current.type}" />"
      ]
    }<c:if test="${!loop.last}">,</c:if>
</c:forEach>

You can also use the conditional operator in EL instead of <c:if>:

    ${!loop.last ? ',' : ''}

+1. A much better solution than mine. @nokheat: you should mark this as the accepted answer. — , Jun 23 '10 at 13:01

score 3 · Answer 2 · edited May 23 '17 at 12:18

One thing I never liked about JSTL (actually I think is the only thing :)) is the fact that there is no way to retrieve the size of a list/collection.

EDIT: ok, so it was possible but I didn't know it :( see here.

The forEach tag has the varStatus attribute which you can use to determine the index of the row (index/count properties on the varStatus variable) but you have to test if you are at the last position in the list, that means having the list size beforehand:

<c:forEach items="${fileList}" var="current" varStatus="status">
   ...
  <c:if test="${not (status.count eq listSize)}">,</c:if>
</c:forEach>

But you will have to place the listSize in scope, manually, before doing this sort of thing.

What I did in one of my projects was to create myself a tag that takes a collection and returns the value:

  <myLib:collectionSize collection="${fileList}" var="listSize" />
  <c:forEach items="${fileList}" var="current" varStatus="status">
     ...
    <c:if test="${not (status.count eq listSize)}">,</c:if>
  </c:forEach>

You could do the same if you have this sort of code often (else you can just add it in scope with whatever is convenient to you).

After a quick search I found this: http://stackoverflow.com/questions/851880/check-a-collection-size-with-jstl. Maybe it can help you even more. — , Jun 23 '10 at 06:29
since the list object has a size() function, can i use list.size to make it look more elegrant? — nokheat, Jun 23 '10 at 06:31
JSTL mainly goes for accessor fields "getProp" and "setProp" and in your JSP you will go for "prop". You could do "list.size" if the list had a method called "getSize" but id doesn't, it just has "size". — , Jun 23 '10 at 06:37
@nokheat: BalusC provided a more cleaner solution to your post. Go for his response. — , Jun 23 '10 at 13:02

score 3 · Answer 3 · edited May 23 '17 at 12:26

3

by Check a collection size with JSTL the answer were to use the functions tag

put this at the top of the page to allow the fn namespace

<%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>

and use like this in your jsp page

<p>The length of the companies collection is : ${fn:length(companies)}</p>

edited May 23 '17 at 12:26

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answered Jun 23 '10 at 07:18

nokheat

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jstl foreach omit an element in last record

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