[xwiki-users] $xwiki not always available?

[Thomas Drevon]

Erin Schnabel wrote:
> 
> I've seen a few of these, and it doesn't really have anything to do
> with the $xwiki reference (though perhaps the code should be changed
> to avoid that misleading message..). The original cause is an NPE
> originating out of Collections.sort, which is called by XWiki.sort:
> 
> XWiki.sort:
> 
>     public List sort(List list)
>     {
>         Collections.sort(list);
>         return list;
>     }
> 
> Collections.sort doesn't appear to check for null:
> 
>     public static <T extends Comparable<? super T>> void sort(List<T> list) {
> 	Object[] a = list.toArray();
> 	Arrays.sort(a);
> 
> Seems to me like your panel needs to make sure your list is non-null
> (not empty) before calling xwiki.sort

Thanks for taking the time to answer me! I see the flaw that you 
pointing out.

> The recommended (from the velocity docs) way to check for non-null && not empty:
> 
> #if( "$!allTags" != '')
>   #set( $allTagsSorted = $xwiki.sort($allTags))
> #end
> 
> That should solve the problem.

I ended up doing something similar:

#set( $allTags = $xwiki.search($query))
#if ( $allTags.size() > 1)
   ...do stuff
#end

However, I'm absolutely positive that my list of tags isn't empty, so 
this can't the ultimate cause of the problem. This was confirmed by 
Sergiu Dumitriu; he recently updated the jira issue concerning the 
inclusion of the above mentioned tag cloud in xwiki. Check it out: 
http://jira.xwiki.org/jira/browse/XE-51


cheers :-)
Thomaas