Hi Boudewijn,
You can set a default value in your custom field "product_url", like: "
yousite.com/index.php?option=com_hikasho...oduct&task=show&cid=
"
And in the product edition page, just add the cid at the end of the url. You can find this url in your browser address bar.
It's possible that the default value doesn't appear on your product configuration page.
If it doesn't appear you will have to edit the view "product / form" in HikaShop > Display > Views (backend template)
And add the lines:
<?php
if(!isset($this->element->$fieldName))
$this->element->$fieldName = $oneExtraField->field_default;
?>
Before:
<?php $onWhat='onchange'; if($oneExtraField->field_type=='radio') $onWhat='onclick'; ?>
<?php echo $this->fieldsClass->display($oneExtraField,$this->element->$fieldName,'data[product]['.$fieldName.']',false,' '.$onWhat.'="hikashopToggleFields(this.value,\''.$fieldName.'\',\'product\',0);"'); ?>