Как получить поле мета автор (php)? - Joomla 2.5: Общие вопросы

$mm1 = json_decode($this->item->metadata);
$mm=$mm1->{'author'}; 
echo $mm;

$mm=$mm1->author; 

$db =& JFactory::getDBO();
$query="запроснебудуписать";
$db->setQuery($query);
$met = $db->loadResult();
$obj = json_decode($met);
$avt=$obj->{'author'}; 

var_dump($this->item->metadata);
$mm1 = json_decode($this->item->metadata);
var_dump($mm1);

JDocumentHTMLstring(53) "{"robots":"","author":"","rights":"","xreference":""}"
object(stdClass)#3801 (4) {
  ["robots"]=>
  string(0) ""
  ["author"]=>
  string(0) ""
  ["rights"]=>
  string(0) ""
  ["xreference"]=>
  string(0) ""
}

var_dump($this->category->metadata);
$mm2 = json_decode($this->category->metadata);
var_dump($mm2);

var_dump($this->category->metadata);
$mm2 = json_decode($this->category->metadata);

var_dump($this->parent_category->metadata);
$mm2 = json_decode($this->parent_category->metadata);

var_dump($this->category->getParent()->metadata);
$mm2 = json_decode($this->category->getParent()->metadata);
var_dump($mm2);

var_dump($this->category->getParent());
$mm2 = json_decode($this->category->getParent());
var_dump($mm2);