How to use sql params in PHP with MySQL

logging.php

<?php
namespace solbs\bookingengine\services;

use mysqli;
use solbs\bookingengine\model\Reservation;

class LoggingService
{
    /**
     * @param MyObject $myobject
     * @param string $pass
     * @param bool $success
     * @return void
     */
    public static function log($myobject, $pass, $success)
    {
        $query = "INSERT INTO records (model, pass, success) VALUES (?, ?, ?)";
        $mysqli = self::getConnection();
        $stmt = $mysqli->prepare($query);
        $stmt->bind_param("s", self::getModel($myobject));
        $stmt->bind_param("S", $pass);
        $stmt->bind_param("i", intval($success));

        $stmt->execute();
        $mysqli->close();
    }

    /**
     * @param MyObject $myobject
     * @return string
     */
    static function getModel($myobject)
    {
        return json_encode($myobject);
    }

    static function getConnection()
    {
        $dbUser = "user";
        $dbPassword = "pass";
        $dbName = "dump";
        $dbServer = "127.0.0.1:3306";

        $mysqli = new mysqli($dbServer, $dbUser, $dbPassword, $dbName);
        $mysqli->set_charset("utf8");
        return $mysqli;
    }
}