getParentIds in plugin??

$modx->getParentIds($id);

<?php
/**
  * create pdf doc on save from resource
  * 
  * only toplevel resources are used as child resources will be sub items pulled in by getResources 
  *
  */

  
  
  ///get proper url to build pdf from
  $url = $modx->makeUrl($id);
  
  $parentIds = implode('-', $modx->getParentIds($id));
  //$parentId = $resource->get('parent');
  
  ///get alias to name pdf file
  $name = $resource->get('alias');
  
  ///build shell command
  $cmd = '/usr/local/bin/wkhtmltopdf -q --margin-bottom 18mm --footer-html http://domain.tld/control/footer.html '.$url.' /var/www/vhosts/domain.tld/httpdocs/control/pdf/'.$name.'-'.$parentIds.'_'.$id.'.pdf';
  
  ///run the command
  shell_exec($cmd);​

<?php
/* will tell you if it's a child or not */
if ($resource->get('parent')) 

/* get the parent object */ 
parentObj->getOne('Parent');

/* is there a grandparent? */
($parentObj->get('parent'))

//etc.

<?php
	/**
	* create pdf doc on save from resource systemEvent:OnDocFormSave
	* 
	* only toplevel resources are used as child resources will be sub items pulled in by getResources 
	*
	* does not work for NEW documents!?
	*
	*/
	
	/**
	 * check if resource is a top level doc or a child
	 *	
	 * @param $res $modx->resource:object
	 * @return top resourse id:int
	 */
	function topparentid($res)
	{
		if($res->get('parent') < 1)
		{
			return $res->get('id');
		}
		else
		{
			$parent = $res->getOne('Parent');
			if($parent->get('parent') < 1)
			{
				return $parent->get('id');
			}
			else
			{
				$grandparent = $parent->getOne('Parent');
				return  $grandparent->get('id');
			}
		}
	}
	
	$resId = topparentid($resource);
	
	///get proper url to build pdf from
	$url = $modx->makeUrl($resId);
	
	//$parentIds = implode('-', $modx->getParentIds($id));
	//$parentId = $resource->get('parent');
	
	///get alias to name pdf file
	$name = $modx->getObject('modResource', $resId)->get('alias');
	
	///build shell command
	//$cmd = '/usr/local/bin/wkhtmltopdf -q --margin-bottom 18mm --footer-html http://domain.tld/control/footer.html '.$url.' /var/www/vhosts/domain.tld/httpdocs/control/pdf/'.$name.'-'.$resId.'_'.$id.'.pdf';
	
	$cmd = '/usr/local/bin/wkhtmltopdf -q --margin-bottom 18mm --footer-html http://domain.tld/control/footer.html '.$url.' /var/www/vhosts/domain.tld/httpdocs/control/pdf/'.$name.'.pdf';
	
	///run the command
	shell_exec($cmd);

$modx->getParentIds($id, 10, array('context' => 'web'));