Zend Session Identity丢失对象参数

class Person extends Zend_Db_Table_Row_Abstract
{
        protected $_cdata = array(); // non-db-table data gets put here through __set()

        public function init()
        {
           $this->fullName = $this->firstName.\" \".$this->lastName; // this is saved to $this->_cdata[\'fullName\']
        } 

$r = $auth->authenticate($authAdapter);
if($r->isValid())
{
  $user = $db->getUserByEmail($email); // Retrieves an object of class \"Person\"
  $auth->getStorage()->write($user);
}

echo $user->fullName; // Will print \"John Smith\" or whatever it is

$auth = Zend_Auth::getInstance();
if($auth->hasIdentity() {
   $user = $auth->getIdentity();
   echo $user->fullName; // Prints nothing...$_cdata[\'fullName\'] does not exist.
}