Accessing $post global variable in content-single-listing-auction.php

Does anyone know, why I can’t access the $post variable in content-single-listing-auction.php?
It works perfectly in content-listing-auction.php, but not in this file.

The thing I want to accomplish is to pick a current price in content-single-listing-auction.php and echo it, so I could pick it with xmlhttpRequest every second and autorefresh it on my listing page.

Something like this:

require($_SERVER[‘DOCUMENT_ROOT’].’/wp-load.php’);
global $post;
$price_current = get_post_meta($post->ID,’price_current’,true);
echo $price_current;

But if I try var_dump($post);

It returns NULL.