php - Return Last Insert ID with PDO -

i have class , extend return id of last inserted row keep getting error:

fatal error: call undefined method pdostatement :: lastinsertid () on line 49

my code:

class db { public static $instance = null;  private     $_pdo = null,             $_query = null,             $_error = false,             $_results = null,             $_count = 0,             $_lastid = 0;  private function __construct() {     try {         $this->_pdo = new pdo('mysql:host=' . config::get('mysql/host'). ';                 dbname=' . config::get('mysql/db') . ';                 charset=utf8',                 config::get('mysql/username'),                 config::get('mysql/password')             );     } catch(pdoexeption $e) {         die($e->getmessage());     } }  public static function getinstance() {     if(!isset(self::$instance)) {         self::$instance = new db();     }     return self::$instance; }  public function query($sql, $params = array()) {      $this->_error = false;      if($this->_query = $this->_pdo->prepare($sql)) {         $x = 1;         if(count($params)) {             foreach($params $param) {                 $this->_query->bindvalue($x, $param);                 $x++;             }         }          if($this->_query->execute()) {             $this->_results = $this->_query->fetchall(pdo::fetch_obj);             $this->_count = $this->_query->rowcount();             $this->_lastid = $this->_query->lastinsertid(); // <- erro         } else {             $this->_error = true;         }     }      return $this; } 

according php docs, lastinsertid method of pdo object, not stmt object (which referencing via $this->_query). try this:

$this->_lastid = $this->_pdo->lastinsertid();