Question

i’m a php novice, and i’m wondering the best way to go about using previously defined class methods from a front facing ajax file. i trolled through 50 or more of the top questions looking for something similar to this, so my apologies if this has been asked before.

my project is set up using a front controller which calls initialize.php, which then includes all the class files i’ve made for this project thus far, whether those class methods/properties will be needed now or not (if this is super bad then someone please tell me an alternative :[[). so basically, for every request made on this site initialize is called, all of those classes are defined and two are instantiated immediately, those two being the classes i use for the database and sessioning/login stuff.

i’ve been doing this in my ajax files:

<?php
// login.ajax.php
require_once 'initialize.php';

$email = $_POST['email'];
$password = $_POST['password'];
$remember = $_POST['remember'];

global $session; // this is instantiated right away every time
$login = $session->login($email, $password);

echo json_encode($login);
?>

recent complications are now making me rethink this approach. constantly loading initialize seems really wasteful, but including/requiring just the necessary class files would be a pain in the ass at best. in this example i’d need to include session, which would also need two other classes to perform this login.

Answer 1

It seems you may wish to use PHP autoloading mechanism.

To see some details, please go to the PHP autoloading documentation. You can read there that:

Many developers writing object-oriented applications create one PHP source file per-class definition. One of the biggest annoyances is having to write a long list of needed includes at the beginning of each script (one for each class).

In PHP 5, this is no longer necessary. You may define an __autoload function which is automatically called in case you are trying to use a class/interface which hasn’t been defined yet. By calling this function the scripting engine is given a last chance to load the class before PHP fails with an error.

Within your initialization file (or separate one, depending on your design decisions) just define __autoload() function that will be used to include required files:

function __autoload($class_name) {
    include_once $class_name . '.php';
}

This should solve the issue / need of multiple requirement / inclusion declarations – from now on, when you instantiate some class and it is not available, newly defined function (__autoload()) will be called to include necessary files.