Calling groovy from a form field

[ernest.hock...@computer.org]

  Hi everyone

I'd like to use groovy to implement some business logic and call that logic
from a button in a form.

E.g Add a button on the product measures form to calculate  the volume
given a product's dimensions..  I've tried

        <field name="calcTest" title=" " widget-style="buttontext">
            <hyperlink description="Calculate C" target="testCalc"
also-hidden="false">
                <parameter param-name="scale-factror"/>
               <!-- e.g add an allowance for packing material -->
            </hyperlink>
        </field>
I can call/test the service "testCalc" from webtools etc but not use the
button.

Can anyone point me to an example in the existing code base that I can use
as a reference model.

thanks in advance

Ernest