未定义的变量＆＃39;令牌＆＃39;

Question

我在这里做错了什么？

<?php

session_start();
$con = mysqli_connect("localhost", "root", "password", "db");

if (!isset($_SESSION['lodge'])) {
    header("Location: lodge.php");
}
$token = mysqli_real_escape_string($con, $_POST['token']);
$res = mysqli_query($con, "SELECT * FROM lodges WHERE lodge_id=" . $_SESSION['lodge']); 
$row = mysqli_fetch_array($res);
if ($row['token'] == ($token)) {
    $_SESSION['lodge'] = $row['lodge_id'];
    header('location:lodge.php');
}

?>

我一直收到undefined variable token错误，似乎无法找到解决方法。