我想获取当前登录的用户ID。通过web浏览器访问时，我成功地做到了这一点。但是，当通过dialogflow将此函数作为webhook/fulfillment调用时，它始终返回ID=0。这是我在PHP中的完整代码。

<?php

/** Absolute path to the WordPress directory. */
if ( !defined(\'ABSPATH\') )
    define(\'ABSPATH\', \'/var/www/html/mine/\');

/** Sets up WordPress vars and included files. */
require_once(ABSPATH . \'wp-config.php\');

do_action( \'plugins_loaded\' );

$current_user = wp_get_current_user();
 
$method = $_SERVER[\'REQUEST_METHOD\'];

// Process only when method is POST
if($method == \'POST\'){
    $requestBody = file_get_contents(\'php://input\');
    $json = json_decode($requestBody);

    $action = $json->queryResult->action;
        
    if ($action == "ngopi"){
        if ($current_user->ID != 0){
            $ngopiResponse = "Hai..".$current_user->display_name;
        }
        else{
            $ngopiResponse = "Hai..Guest";  
        }   
    }
    
    $response = new \\stdClass();
    $response->speech = $ngopiResponse;
    $response->fulfillmentText = $ngopiResponse;
    $response->source = "webhook";
    echo json_encode($response);
}
else
{
    echo "Method not allowed";
}
?>

提前谢谢。