protected function getOurValue()
    {
        if ($this->owner->loaded()) {
            return $this->our_field
                ? $this->owner[$this->our_field]
                : $this->owner->id;
        } else {
            // create expression based on existing conditions
            return $this->owner->action(
                'field',
                [
                    $this->our_field ?: ($this->owner->id_field ?: 'id'),
                ]
            );
        }
    }