Sorting an array of strings in VTL

Question

Being mainly a VB.NET programmer, I am extremely new to VTL (Velocity Template Language). I am currently trying to customise an application that uses Velocity templates and Jython.

I have the following VTL code in an existing file. This code obtains some key-value pairs from a JSON file and outputs them to the browser in a neat table:

<table class="meta">
    #set($keySet = $metadata.getJsonObject().keySet())
    #foreach($key in $keySet)
    <tr>
        <th width="25%">$parent.getFriendlyName($key)</th>
        <td>
            #set($valueList = $metadata.getList($key))
            #if($valueList.size() > 1)
                #foreach($value in $valueList)
                    <span class="meta-value">$self.escape($value)</span><br/>
                #end
            #else
                $self.escape($valueList.get(0))
            #end
        </td>
    </tr>
    #end
</table>

I can display the $keySet array:

[field1, field2, field3, field4]

What I am attempting to do is to sort the strings in the $keySet array in alphabetical order.

I have tried to use the SortTool (http://velocity.apache.org/tools/devel/javadoc/org/apache/velocity/tools/generic/SortTool.html) by changing

#foreach($key in $metadata.getJsonObject().keySet())

to

#foreach($key in $sorter.sort($metadata.getJsonObject().keySet()))

but the array returned by the sort() function is empty.

Also, I did not think that the solution listed in http://www.liferay.com/community/forums/-/message_boards/message/11146823 was applicable as I am not trying to sort on a child field.

Any advice would be greatly appreciated. Thanks in advance.

Answer 1

First thing to check is if you have added SortTool to the velocity context, using code like:

VelocityContext velocityContext = new VelocityContext();
velocityContext.put("sorter", new SortTool());

Having said that, best practice would be to do this kind of work in Java code, not in the template logic. See my answer here for more details and reasons.