thetool/application/PreordercampaignApiuser/PreordercampaignApiuser.php

<?php

class PreordercampaignApiuser extends mfBaseModel {

    protected function beforeUpdate($data) {
        if(!array_key_exists("edit_by", $data)) {
            $me = new User();
            $me->loadMe();
            $data["edit_by"] = $me->id;
        }

        return $data;
    }

}