Wednesday, March 21, 2007

JSP EL expressions are being ignored by tomcat

tomcat JSP JSTL EL

Hopefully this is my last post about the possible problems with JSP/web-app specs and EL. In this case, there's a JSP using EL

String myUrl = (String)session.getAttribute("SESSION_KEY_MY_URL");
pageContext.setAttribute("myUrl", returnUrl);
<form name="load" action="${myUrl}" method="GET">

It's coming out in HTML with the EL untouched (but the scriptlet is definitely being run).

<form name="load" action="${myUrl}" method="GET">

Why is the EL being ignored?

As with the previous 2 posts on this issue, you have to fix the schema reference in the web.xml (there's too many differing copies of the web.xml(s) I'm dealing with here) and make sure the JSP has the right tablib uri reference - see this post.

For the first time I found this didn't immediately solve the problem! The HTML is coming out the same with EL unevaluated. The issue is that the JSP has been compiled to TOMCAT_HOME\work\Catalina\localhost\MyApp\org\apache\jsp\jsp\myfolder\ and tomcat sees no need to recompile even though I've updated the spec of the webapp.

The solution is to stop tomcat, remove the contents of TOMCAT_HOME\work and restart (OR update the timestamp on the JSP source file(s) to force recompilation). The JSP will be recompiled (to the right spec 2.0 now) and the EL will be evaluated as you expect.

1 comment:

Anonymous said...

oh man. excellent find! I had updated my web.xml schema to be 2.5... but I just couldn't figure out the problem!