If I include a file, I will get Include error - php

Question

I have a smarty project:
in the devidate_server.php:
<?php
include($_SERVER['DOCUMENT_ROOT'] . '/ax/ax_conf/CONSTANTS.php');
include($_SERVER['DOCUMENT_ROOT'] . '/ax/utils/utils.php');
...
there I will get error, but I can not get the error information, because I am develop WHMCS, I don't know the traceback's place. Give me information is the interface is blank.
But if I comment the include($_SERVER['DOCUMENT_ROOT'] . '/ax/utils/utils.php'); there will not get error.
There will shows the interface content.
in the utils.php there is:
<?php
include($_SERVER['DOCUMENT_ROOT'].'/qi_cloud/utils/http_util.php');
include($_SERVER['DOCUMENT_ROOT'].'/qi_cloud/qi_cloud_config/urls.php');
include($_SERVER['DOCUMENT_ROOT'].'/qi_cloud/libs/Requests/library/Requests.php');
Requests::register_autoloader();
function fetch_qicloud_access_tokens($params){
$result = Requests::post('http://localhost:8000/o/token', [
// headers
'Accept'=>'application/json'
], $params, [
// options
'auth' => new Requests_Auth_Basic([QICLOUD_whmcs_pj_client_id, QICLOUD_whmcs_pj_client_secret])
]);
return $result;
}
I don't know why I get include error, who can help me why I comment that line there will be normal?
EDIT-01
I get the error log:
[Wed Jul 18 11:26:52.040872 2018] [proxy_fcgi:error] [pid 29189:tid 139662983087872] [client 118.113.136.133:29440] AH01071: Got error 'PHP message: PHP Warning: require(/usr/local/httpd/htdocs/whmcs/qi_cloud/libs/Requests/library/Requests.php): failed to open stream: No such file or directory in /usr/local/httpd/htdocs/whmcs/qi_cloud/utils/http_util.php on line 9\nPHP message: PHP Warning: require(/usr/local/httpd/htdocs/whmcs/qi_cloud/libs/Requests/library/Requests.php): failed to open stream: No such file or directory in /usr/local/httpd/htdocs/whmcs/qi_cloud/utils/http_util.php on line 9\nPHP message: PHP Fatal error: require(): Failed opening required '/usr/local/httpd/htdocs/whmcs/qi_cloud/libs/Requests/library/Requests.php' (include_path='.:/usr/share/pear:/usr/share/php') in /usr/local/httpd/htdocs/whmcs/qi_cloud/utils/http_util.php on line 9\n', referer: http://www.example.net/clientarea.php
EDIT-2
the qi_cloud/utils/utils.php
<?php
include($_SERVER['DOCUMENT_ROOT'].'/qi_cloud/utils/http_util.php');
include($_SERVER['DOCUMENT_ROOT'].'/qi_cloud/qi_cloud_config/urls.php');
include($_SERVER['DOCUMENT_ROOT'].'/qi_cloud/libs/Requests/library/Requests.php');
Requests::register_autoloader();
...
the urls.php
<?php
require('./CONSTANTS.php');
define('qicloud_oauth_token_url', QICLOUD_BASE_API . 'o/token/'); //
the CONSTANTS.php:
<?php
define('QICLOUD_BASE_API', 'http://103.200.32.76:8000/');
...

Answer 1

You should not rely on documents root.
Do something like:
require_once(DIR . '/relative/path/from/current/directory/file.php');
The require once will stop execute ifbfile is not there since it's require. The once will make sure you don't include the file twice if you pass by this code a second time. You should never include a file that as finction/class/constant declaration more than one. And if you use a proper IDE (like phpstorm) you will have a warning if the file path is invalid. This cannot be achieved with the document root variable.
But I don't know your exact contalext but you should check something like composer.json to handle your dependencies.
P.s. there is 2 underscore before and after the DIR magic constant but formatting on the mobile web version is limited and force bold...