未捕获的错误：使用$ this

Question

I've seen other posts about this but I just can't understand them, what is the solution here, can you guys show me? Please. Static or not static? What does it mean? Is this the problem?

Db connection code:-

<?php 
define('DB_SERVER', 'localhost'); 
define('DB_USERNAME', 'root'); 
define('DB_PASSWORD', ''); 
define('DB_DATABASE', 'not telling'); 
class DB_con { 
    public $connection; 
    function __construct(){ 
        $this->connection = new mysqli(DB_SERVER, DB_USERNAME, DB_PASSWORD,DB_DATABASE); 
        if ($this->connection->connect_error) 
            die('Database error -> ' . $this->connection->connect_error); 
    } 
    function ret_obj(){ 
        return $this->connection; 
    } 
}

Code for fetching records:-

<?php

$role_id = (isset($_SESSION['role_id']) ? $_SESSION['role_id'] : 4) ;

$query = "
   SELECT rights_codename FROM permissions 
   INNER JOIN roles_and_permissions ON fk_permissions_id = permissions_id
   WHERE fk_role_id = $role_id
   ";

$_SESSION['permissions'] = array();
$result = $this->db->query($query);
while($row = $result->fetch_assoc()){

   array_push($_SESSION['permissions'], $row['permissions_cname']);

 //  $_SESSION['permissions'][] = $row['permissions_cname'];

}
if(in_array('admin_rediger_bruger',$_SESSION['permissions'])){
}

?>

Fatal error: Uncaught Error: Using $this when not in object context in C:\xampp\htdocs\R_L_E\login.php:30 Stack trace: #0 {main} thrown in C:\xampp\htdocs\R_L_E\login.php on line 30

Answer 1

In lay man terms, $this is when you are referencing a non static function in a class. What you can do is create a new instance of the database class and then use that variable created during instantiation to access the member functions of that class

Do this

$conn = new DB_con();//instantiate the class.add this at the very top of login.php
$conn->connection->query('your sql stuff');//replace the $this->db->query($query) with this line 

You can access the connection property as it is declared as public in your class

Also do not forget to include the DB_con file