[SOLVED] Store data in a new db field

    case 'OnDocFormSave':
        /* do processing logic here. */
        $resource =& $scriptProperties['resource'];
        $resource->set('description',$_POST['shorturl']);
        $resource->save();
        break;
}
return;

    case 'OnDocFormSave':
        /* do processing logic here. */
        $resource =& $scriptProperties['resource'];
        $resource->set('shorturl',$_POST['shorturl']);
        $resource->save();
        break;
}
return;

[[*shortUrl]] 

$docInfo = $modx->getObject('modResource',18);
$docname = $docInfo->get('alias');
$doctypeid = $docInfo->get('content_type');

<?php
$resource = $modx->getObject('modResource',18);

$contentType = $resource->getOne('ContentType');

$description = $contentType->get('description');
$mimeType = $contentType->get('mime-type');

<?php
/* Retrieve properties from DB */

$Bitly_KEY = $modx->getOption('Bitly_KEY', $scriptProperties, '');
$Bitly_LOGIN = $modx->getOption('Bitly_LOGIN', $scriptProperties, '');
$siteURL = $modx->getOption('site_url');
$docInfo = $modx->getObject('modResource',18);
$docname = $docInfo->get('alias');

//damn I am unable to retrieve file extension

/* Check if it is in folder */
$parent = $docInfo->get('parent');
$path='';

/* Checks if everything is correct */

if (empty($Bitly_KEY)){
	$output="-No Bit.ly key, please create an account @ bit.ly website";
	return $output;
	die();
	}
	else
	{
		$output=$Bitly_KEY;
		}

if (empty($Bitly_LOGIN)){
	$output="-No Bit.ly key, please create an account @ bit.ly website";
	return $output;
	die();
	}
	else
	{
		$output=$Bitly_LOGIN;
		}

//loop through parents
while ($parent != 0) {
	$docInfo = $modx->getObject('modResource',$parent);
	$alias = $docInfo->get('alias');
	$path = $alias . '/' . $path;
	$parent = $docInfo->get('parent');
	}

$longurl = $siteURL . $path . $docname . $extension;
$bitly = 'http://api.bit.ly/shorten?version=2.0.1&longUrl='.urlencode($longurl).'&login='.$Bitly_LOGIN.'&apiKey='.$Bitly_KEY.'&format=xml';
$response = file_get_contents($bitly);
//credits to davidwalsh.name
//parse depending on desired format
if(strtolower('xml') == 'json'){
	$json = @json_decode($response,true);
	return $json['results'][$longurl]['shortUrl'];
	}
	else //xml
	{
		$xml = simplexml_load_string($response);
		return 'http://bit.ly/'.$xml->results->nodeKeyVal->hash;
	}

<?php
$resource = $modx->getObject('modResource',18);

$contentType = $resource->getOne('ContentType');

$extension = $contentType->get('file_extensions');