Question

I’m trying to build a tiny ORM class that models will extend so, if for example I call the method User::find(1) it will give me the ‘User’ model that haves the id of 1 in the database.

This is my attempt:

class ORM
{
    private static $table, $database;

    function __construct() {
        self::getConnection();
    }

    private static function getConnection (){
        require_once('Database.php');
        error_log('Getting connection');
        self::$database = Database::getConnection(DB_PROVIDER, DB_HOST, DB_USER, DB_PASSWORD, DB_DB);
    }

    public static function find($id) {
        $obj = null;
        self::getConnection();
        $query = "SELECT * FROM ? WHERE id = ?";
        $results = self::$database->execute($query,null,array(self::$table,$id));
        print_r();
        if ($results){
            $obj = new self($results);
        }
        return $obj;
    }
}

And then, the class User for example.

include('ORM.php');
include('../../config.php');

class User extends ORM
{
    public $id, $name;
    private static $table = 'user';

    public function __construct($data){
        parent::__construct();
        if ($data && sizeof($data)) { $this->populateFromRow($data); }
    }

    public function populateFromRow($data){
        $this->id = isset($data['id']) ? intval($data['id']) : null;
        $this->name = isset($data['name']) ? $data['name'] : null;
    }
}

print_r(User::find(1));

I put those includes and that print_r just for testing, it won’t remain there after.

The issue is that it seems that the method find doesn’t read the $table from the class and it doesn’t read nothing. So the query isn’t executed fine and returns nothing but an error.

What am I doing wrong?

Answer 1

Change self in your code to static. Note that it will only work in php >= 5.3. Read more about late static binding