mysqli stmt return result

How to return result from mysqli stmt prepare and bind_param statement.
Please note that you must install  MySQL Native Driver (mysqlnd) driver to use get_result();


DBClient.php

<?php
//error_reporting(E_ALL ^ E_DEPRECATED);
class DBClient {
var $host,$db,$user,$pass;
var $mysqli,$isDBConnect;
function __construct() {
    $this->host = "localhost";
    $this->db = "mydb";
    $this->user = "root";
    $this->pass = "pass";
    try {
          $this->mysqli = new mysqli($this->host, $this->user, $this->pass,$this->db );
        if ($this->mysqli->connect_error) {
            die('Error : ('. $this->mysqli->connect_errno .') '. $this->mysqli->connect_error);
        }
    } catch(Exception $ee) {
        $this->link=false;
           $this->isDBConnect=false;
    }
}

public function autocommit_false() {
    $this->mysqli->autocommit(FALSE);  
}

public function commit() {
    $this->mysqli->commit();  
}

public function rollback() {
    $this->mysqli->rollback();
}
public function close() {
    $this->mysqli->close();
}

}
?>


Part_Wise_Class.php
<?php
class Part_Wise_Class {  
    public function part_wise_get_part_nm($class_id,$subject_id) {
        $ssql = "SELECT part_id,part_nm from part_info WHERE class_id =? and subject_id=?";
        $db=new DBClient();
        $stmt = $db->mysqli->stmt_init();
        $stmt = $db->mysqli->prepare($ssql);
        $stmt->bind_param("ii",$class_id,$subject_id);
        $stmt->execute();
        $result = $stmt->get_result();
        $db->close();
        return $result;
   }  
}
?>



test.php
<?php
include_once("DBClient.php");
include_once("Part_Wise_Class.php");  
$part_wise=new Part_Wise_Class();
$class_id=$_GET['class_id'];
$subject_id=$_GET['subject_id'];
$result=$part_wise->part_wise_get_part_nm($class_id,$subject_id);
$rows = array();
while ($row = $result->fetch_array(MYSQLI_BOTH)) {
            echo $row['part_id'];
}
?>