Problems with JSTL
 

Hi I use the tag library and i have following Problem.

<c : out value="${nickname}"/>

Output of this statement is ${nickname} and not the value of the variable nickname. I have no clue what i m doing wrong. jar's and tld's are in the right directory.

Following is on the top of my jsp.

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

using Tomcat 5.X

Re: Problems with JSTL
 

what variable 'nickname' are you trying to output?
JSTL will use any named attribute from the pagecontext, not something you created in a Java block on the JSP (in fact you should avoid those like the plague).

Re: Problems with JSTL
 

yeah that is my problem. You are totaly right. So if i need variables i transfer from my servlet to my JSP <c:out... is not the right way? Should I use <%=.... instead?

Re: Problems with JSTL
 

When you reference ${nickname} from JSTL, what the JSP is doing is looking in either the request object for a nickname attribute or the session object [i.e., request.getAttribute("nickname")]. So if you want to use ${nickname} from JSTL but set it in your servlet, then do request.setAttribute("nickname", "My Nickname");

If you want to set values in the JSP, then use the <c:set> JSTL tag.

The most important thing about getting JSTL to work, and is documented almost no where, is you have to use a Servlet 2.4 style web.xml instead of a Servlet 2.3 style web.xml.

To do this, make sure the top of your web.xml looks like this:

<?xml version="1.0" encoding="ISO-8859-1"?>

<web-app xmlns="http://java.sun.com/xml/ns/j2ee"

    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/

ns/j2ee/web-app_2_4.xsd"

    version="2.4">

From the sound of things, this might actually be your problem, because if you're using a 2.3 style web.xml, then I don't think it will recognize the EL expressions. ${nickname} is an EL expression.

Re: Problems with JSTL
 

Wrong, dead wrong.
You need a 2.4 servlet container ONLY to use JSTL 1.1. The questions are clearly related to JSTL 1.0 which is part of the 2.3 spec (though may need separate installation of the JSTL jars depending on appserver in use).

Re: Problems with JSTL
 

This is a Tomcat-specific issue with the Apache JSTL implementation. If you don't use a 2.4 web.xml, the EL expressions don't get evaluated in the JSP.

Re: Problems with JSTL
 

Many thanks. Nice hint! Before anyone else gets insane one more hint: of course, you have to recompile all jsps to see it work after changing the web.xml.
a
find <docroot> -name "*.jsp" | xargs touch
will do the rest... ;-)

Re: Problems with JSTL
 

Be sure to never tell that to the 30 or so Tomcat instances running with our customers.