ERROR in PDO : Call to a member function prepare() on null

Question

I have a problem with prepare function ==> Call to a member function prepare() on null i have tow pages classo.php and index.php

classo.php :

    <?php 

        class classo
        {

            function connection(){

                $db=new pdo ('mysql:host=localhost;dbname=pronostic','root','');
                $db->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_WARNING);

            }



            function insererDonne($pseudo,$password)
            {      
                        global $db;
                        classo::connection();     
                $donne=array(
                    'user' =>$pseudo,
                    'pass' =>$password 
                    );

                $req="INSERT INTO users (user,pass) VALUES (:user,:pass)";

                $sql=$db->prepare($req);

                $sql->execute($donne);

            }



        }


 ?>

index.php:

<?php 


require('classo.php');


$data=new classo();
$data->insererDonne('dsds','tosdsta');


 ?>

Do you have an idea as to how I can resolve this? This is the first time I've received this error from PHP and I'm kind of new coding in PHP with objects & classes. Could someone help me fix this problem please?

Answer 1

There are 2 big issues in your code:

1. Variable visibility
2. Static call

In detail:

1. In oop you should forget about global variables. They are against the principle of encapsulation. Moreover, you do not even have any global variable in your code, so global $db; line is meaningless. Declare a private $db variable on class level (property) initialise it in the connection() method and access it in the insert method.

2. You are calling the connection method as classo::connection();. However, you would need to declare connection method as static. Either declare your connection method as static (but then change $db into static as well), or call it as a regular method using $this.