Different behavior of the c Tag between version 17 and version 18 in OpenCMS

[rgaviras]

Here's a simple example of the issue:

We have a resource with a formatter like this:

<%@ page contentType="text/html;charset=UTF-8" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

<c:redirect url="https://www.google.com"/>

In version 16, if the resource is on a page, the redirect works as expected. However, in version 18, this fails and returns the following error on the page:

Error parsing element /en-en/page/.elements/Banner_00001.xml. Please check if the HTML generated by the element formatter is well formed.

To test this, it’s recommended to first create the formatter without the redirect; otherwise, it won't allow you to drag it onto the page, whether it works or not.

This is just a sample to replicate the issue. In the actual case, this code is within a function that performs the redirect based on specific logic.

[rgaviras]

I've tested on OpenCms17 and works as expected... the diference is on version 18

[rgaviras]

Does anyone know or can think of an alternative to bypass this error? Or any hints on where to look?
We're a bit lost, and a large part of our development depends on a method like this.

[chemajf]

Hello,
Problem:
I have debugged the code from the TAG Builds_18_0 and I believe the issue is in the method org.opencms.loader.CmsJspLoader#dispatchJsp, specifically in the last else if (line 1109):

In the case where the JSP is a dynamic function, the method controller.isTop() always returns false, which means the redirection is never performed even if it exists, and null is returned, causing the error.
I am not sure why controller.isTop() always returns false.

Patch:
To trigger the redirection, I modified the code so that if we have RedirectInfo and the redirection contains "http", it performs the redirection without checking controller.isTop():

If this condition is not met, the original check is performed as before.

I don't believe this is the proper solution, but rather a temporary patch to address this issue.

I hope this information helps in resolving the problem.

Best regards.