An empty tag in a custom tag-lib causes an Exception

[Christopher M Meyer <cm...@us.ibm.com>]

Good afternoon,

I posted this as a bug here:
https://issues.apache.org/jira/browse/MYFACES-3988

At the request of Mike I am resposting the question here to elicit some
feedback. Here were his other comments:

Also, is your Glassfish/Wildfly container using Mojarra as the JSF
implementation?


If nothing else, MyFaces could provide a configuration parameter which
would ignore empty render type tag contents and continue onward. Do you
mind submitting a patch to provide such behavior?

To answer Mike's questions: I tested this on Glassfish 4.1 using Mojarra
2.2.7:

[2015-04-29T15:18:19.896-0400] [glassfish 4.1] [INFO]
[jsf.config.listener.version]
[javax.enterprise.resource.webcontainer.jsf.config] [tid: _ThreadID=87
_ThreadName=Thread-26] [timeMillis: 1430335099896] [levelValue: 800] [[
  Initializing Mojarra 2.2.7 ( 20140610-1547
https://svn.java.net/svn/mojarra~svn/tags/2.2.7@13362) for context '']]

Using my simple test a text box is displayed using Mojarra, but it isn't
displayed with MyFaces.



For reference, here is my original post:

While developing a custom tag library we added an empty renderer-type tag
like this:


<tag>
<tag-name>myinput</tag-name>
<component>
<component-type>my.test.MyInput</component-type>
<renderer-type></renderer-type>
</component>
</tag>


This causes the following exception:


Caused by: java.lang.Exception: Value Cannot be Empty
at
org.apache.myfaces.view.facelets.compiler.TagLibraryConfigUnmarshallerImpl
$LibraryHandler.endElement(TagLibraryConfigUnmarshallerImpl.java:395)
at org.apache.xerces.parsers.AbstractSAXParser.endElement(Unknown Source)
at org.apache.xerces.impl.XMLNSDocumentScannerImpl.scanEndElement(Unknown
Source)
at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl
$FragmentContentDispatcher.dispatch(Unknown Source)
...


This appears to be expected based on the code in
TagLibraryConfigUnmarshallerImpl. From what I can see the exception appears
to be thrown on elements which are used in another spot. If any of them are
empty they will throw the above exception. Wildfly/Glassfish does not have
the same behavior, so my assumption is they just ignore it.


Should the MyFaces code be modified to just continue on without the
exception, based on the reference implementation? I can quickly create
something if so, I just wanted to bring this up to the community at large
since I don't know the reasoning behind the difference of the
implementations.


Christopher Meyer
Software Developer
(919) 543-9782
T/L: 441-9782