How to exclude attribute in XML

[bokasmoka]

Hello! 
This is my current situation:
I started using PS API (webService), but I have a problem.

I want to update(edit) products name. I'm not sure how do I do that.. At this moment I'm only able to display all of the attributes that a node contains. I want to be able to take whatever attributes i need. 

Here is the code (part of it) that I think I need to modify:

 

if (isset($_GET['id']) && isset($_POST['id'])) // Here we check id cause in every resource there's an id
{
	// Here we have XML before update, lets update XML with new values
	foreach ($resources as $nodeKey => $node)
      $resources->$nodeKey = $_POST[$nodeKey];

}
	// And call the web service
	try
	{
		$opt = array('resource' => 'products');
		$opt['putXml'] = $xml->asXML();;
		$opt['id'] = $_GET['id'];
		$xml = $webService->edit($opt);

		// if WebService don't throw an exception the action worked well and we don't show the following message
		echo "Successfully updated.";
	}
	catch (PrestaShopWebserviceException $ex)
	{
		// Here we are dealing with errors
		$trace = $ex->getTrace();
		if ($trace[0]['args'][0] == 404) echo 'Bad ID';
		else if ($trace[0]['args'][0] == 401) echo 'Bad auth key';
		else echo 'Other error<br />'.$ex->getMessage();
	}

Please check the image that i attached to see the error that I get. 

So I guess my question is: How to exclude an attribute from this XML?

Thanks!