Extending mysqli and using multiple classes

I'm new to PHP oop stuff.

I'm trying to create class database and call other classes from it. Am I doing it the right way?

class database:

class database extends mysqli {

private $classes = array();

public function __construct() {
parent::__construct('localhost', 'root', 'password', 'database');
    if (mysqli_connect_error()) {
    $this->error(mysqli_connect_errno(), mysqli_connect_error());
    }
}

public function __call($class, $args) {
    if (!isset($this->classes[$class])) {
    $class = 'db_'.$class;
    $this->classes[$class] = new $class(); 
    }
return $this->classes[$class];
}

private function error($eNo, $eMsg) {
die开发者_高级运维 ('MySQL error: ('.$eNo.': '.$eMsg);
}

}

class db_users:

class db_users extends database {

public function test() {
echo 'foo';
}

}

and how I'm using it

$db = new database();
$db->users()->test();

Is it the right way or should it be done another way?

Thank you.

You can do it that way, there's nothing wrong with that (I do something similar quite often). The only thing I would suggest is using exceptions instead of die (that way you can safely handle the error)...

protected function error($eNo, $eMsg, $extra = '') {
    throw new Exception('MySQL error: ['.$eNo.'] '.$eMsg.': '.$extra);
}

Plus, I'd suggest overloading the query method as well

public function query($sql, $result_mode = MYSQLI_STORE_RESULT) {
    $result = parent::query($sql, $result_mode);
    if ($result === false) {
         $this->error($this->errno, $this->errstr, $sql);
    }
    return $result;
}

I'd also suggest storing a copy of the $db object inside of the child class. So:

class db_users extends database {
    protected $db = null;

    public function __construct(Database $db) {
        $this->db = $db;
    }

    public function test() {
        echo 'foo';
    }
}

Then, in __call:

if (!isset($this->classes[$class])) {
    $class = 'db_'.$class;
    $this->classes[$class] = new $class($this); 
}

There is nothing wrong with this factory style for creating classes. I'd place a bit of exception handling in it.

My only other concern is extending database in your sub classes.

So I'd modify as follows:

public function __call($className, $args) {
    if (!isset($this->classes[$class])) {
        if(include_once('db_'.$class)) {
            $class = 'db_'.$class;
            $this->classes[$class] = new $class($this);
        } else {
            throw new Exception("Db class not found");
        }
    }

    return $this->classes[$class];
}

And the users class as:

public class db_users {
    private $db;

    public __constructor($db) {
        $this->db = $db;
    }

    public function test() {
        return 'Foo';
    }
}