Problem
In JSF 2.0, comment out a JSF tag like this
JSF…
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://java.sun.com/jsf/html"
>
<h:body>
<!--
<h:commandButton type="button"
value="#{msg.buttonLabel}" />
-->
</h:body>
</html>
But JSF still process the value expression and output the result to the generated HTML page. Assuming that #{msg.buttonLabel} is return a “Submit” message.
Generated HTML page…
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "
http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<body>
<!--
<h:commandButton type="button"
value="Submit" />
-->
</body>
</html>
Is there a way to comment out a JSF tag completely? No process on the value expression or appear in the final generated HTML page?
Solution
There are two ways to comment out JSF tag :
1. facelets.SKIP_COMMENTS
In web.xml, set “facelets.SKIP_COMMENTS” parameter to “true“.
<context-param>
<param-name>facelets.SKIP_COMMENTS</param-name>
<param-value>true</param-value>
</context-param>
Now, JSF removes anything in the page that is contained in <!– –>.
JSF…
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://java.sun.com/jsf/html"
>
<h:body>
<!--
<h:commandButton type="button"
value="#{msg.buttonLabel}" />
-->
</h:body>
</html>
Generated HTML page…
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "
http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<body>
</body>
</html>
2. ui:remove
Alternatively, you can use the “ui:remove” tag to define the content you want to remove. For example,
JSF
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:ui="http://java.sun.com/jsf/facelets"
>
<h:body>
<ui:remove>
<h:commandButton type="button"
value="#{msg.buttonLabel}" />
</ui:remove>
</h:body>
</html>
Generated HTML page…
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "
http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<body>
</body>
</html>
Download Source Code
Download It – JSF-2-Remove-Tag-Example.zip (10KB)
May want to update: facelets.SKIP_COMMENTS is deprecated … use javax.faces.FACELETS_SKIP_COMMENTS
The tutorial should be really updated then.
Thank you, it works perfect
Thank you
I included the first solution in my web.xml configuration file. Now, my team and me can include comments in the .xhtml files. Thanks
Please note that javax.faces.FACELETS_SKIP_COMMENTS is now supposed to be used.
made my day!
Very good tutorial. Thank you!
thank you for this good tutorial
Really doing to wonderful job. Keep it up
Using Mojarra 2.1.7 now, “facelets.SKIP_COMMENTS” is deprecated. Use “javax.faces.FACELETS_SKIP_COMMENTS” instead.
A good catch. I was wondering what does JSF process the value expressions in the XML comments. In the Core Java Server Faces book I got to know that this feature was meant for use in JavaScript code inside comments.
Not having much knowledge about JavaScript, I was not able to clearly understand this. Any idea?
In the above comment I meant “Why does JSF process the value expressions in the XML comments”.
This is how JSF work :), and you can skip it easily, see above solution.
As the book mentioned there is reason behind having this feature of processing the commented statements. It says that it is for use in the JavaScript code inside comments. I didn’t understood this, did you?
In the old days, one used to put Javascript inside comments so that older browsers that didn’t support javascript would ignore it. Not sure its relevant today.
sorry but I do not see the interest of executed el inside comments. Why JSF unnecessarily complicates the work of programmers with behaviors that are obviously nonsense?
is a HTML comment, not EL. That is why the EL code is still being executed. See javax.faces.FACELETS_SKIP_COMMENTS for a quick fix and you have your wished behavior.
You are to young my child. Long time ago there was a decision about JavaScript in a comment block. This is a backward compatibility.