velocity support: testing for null in operationBinding.values

Technical Q&A
1

I’m trying to test for null (not ‘not defined’, but === null), but it’s not working.

I use the approach described here http://wiki.apache.org/velocity/CheckingForNull
(approach number 3)

((! $values.FILA_ASSEGNATA) && (“$!values.FILA_ASSEGNATA” == “”))

is it possible to configure velocity support to use other approaches? Maybe number 4 or 6 on that wiki page?

this is the complete operationBinding.values I’m using:
<values fieldName=“FILA_PRECEDENTE”>
<value>
#if ((((! $values.FILA_ASSEGNATA) && (“$!values.FILA_ASSEGNATA” == “”))) && $dsRequest.oldValues.FILA_ASSEGNATA)
$dsRequest.oldValues.FILA_ASSEGNATA
#else
$dsRequest.oldValues.FILA_PRECEDENTE
#end
</value>

2

Any kind of configuration would involve writing a DMI - if you’re going to write a DMI, you can easily do a null check in Java instead.