include_once(): 无法打开流：没有这样的文件或目录 - PHP

Question

I was trying to make a simple signup system in php. I have a class called Admin(inside controller folder) which extends the DBConnection.php class. Admin class have a signup method for letting adming signup but got problem there. Error occurs at 'include_once' and error says 'Warning: include_once(../Database/DBConnection.php): failed to open stream: No such file or directory in C:\\xampp\\htdocs\\WoodlandsAway\\controller\\Admin.php on line 15----- ' 'Warning: include_once(): Failed opening '../Database/DBConnection.php' for inclusion (include_path='C:\\xampp\\php\\PEAR') in C:\\xampp\\htdocs\\WoodlandsAway\\controller\\Admin.php on line 15----- ' 'Fatal error: Class 'DBConnection' not found in C:\\xampp\\htdocs\\WoodlandsAway\\controller\\Admin.php on line 17'

here is my include_once code

include_once ('../Database/DBConnection.php');

And here is my folder structure

--DBConnection.php

class DBConnection {
//put your code here
private $host;
private $user;
private $pass;
private $database;
private $conn;

function DBConnection() {
    $this->host = 'localhost';
    $this->user = 'root';
    $this->pass = '';
    $this->database = 'woodlands_away';
}

public function getConnections() {
    $this->conn = new mysqli($this->host, $this->user, $this->pass, $this->database) or
    die($this->conn->error);

    return $this->conn;
}

}

And Admin.php

include_once ('../Database/DBConnection.php');

class Admin extends DBConnection {
public function Admin() {
    parent::DBConnection();
}

public function signup($username, $password) {
    $sql = "insert into users values(".$username.", ".$password.")";

    return $this->getConnections()->query($sql);
}}

Answer 1

First, I suggest you to declare a constant that represents the root path of your project. This constant must be declared in a unique way such an index.php or similar, but in the root of your project:

define('PROJECT_ROOT_PATH', __DIR__);

Then your include call should looks like this:

include_once (PROJECT_ROOT_PATH . '/Database/DBConnection.php');

(Always specify the leading slash)

The problem is that currently your code may rely on the Working directory so you probably get an unexpected working directory.