连接时出现OOP PHP错误

Database file

define("DB_HOST","localhost");
define("DB_USER","faizy");
define("DB_PASS","faizy");
define("DB_NAME","gallery_db");
?>

Database Class

<?php
    class Database {
        public $connection;

        function __construct() {
            $this->open_db_connection();
        }

        public function open_db_connection() {
            $this->connection = mysqli_connect(DB_HOST,DB_USER,DB_PASS,DB_NAME);

            if(mysqli_connect_errno) {
                die ("database fails badly" . mysqli_error());
            }
        }
    }

    $database = new Database();
?>

Template

<div class="row">
    <div class="col-lg-12">
        <h1 class="page-header">
            Dashboard <small>Statistics Overview</small>
        </h1>

        <?php
            if($database->connection) {
                echo 'true';
            }
        ?>
    </div>
</div>

Error

Notice: Undefined variable: Notice: Trying to get property of non-object

I am using object oriented PHP and trying to give connection eror in a simple template,But is is giving another error discuss below, Can anyone suggest or resolve my problem and i have done all the includes and all

try this , using $ before database, hope it will work

$database = new Database();

Notice: Undefined variable Error is because you are using mysqli_connect_errno in your Database class but mysqli_connect_errno is a Function in PHP, Hence replace mysqli_connect_errno with mysqli_connect_errno().