Getting the name of a child class in the parent class (static context)

saalaa picture saalaa · Nov 12, 2008 · Viewed 84.7k times · Source

I'm building an ORM library with reuse and simplicity in mind; everything goes fine except that I got stuck by a stupid inheritance limitation. Please consider the code below:

class BaseModel {
    /*
     * Return an instance of a Model from the database.
     */
    static public function get (/* varargs */) {
        // 1. Notice we want an instance of User
        $class = get_class(parent); // value: bool(false)
        $class = get_class(self);   // value: bool(false)
        $class = get_class();       // value: string(9) "BaseModel"
        $class =  __CLASS__;        // value: string(9) "BaseModel"

        // 2. Query the database with id
        $row = get_row_from_db_as_array(func_get_args());

        // 3. Return the filled instance
        $obj = new $class();
        $obj->data = $row;
        return $obj;
    }
}

class User extends BaseModel {
    protected $table = 'users';
    protected $fields = array('id', 'name');
    protected $primary_keys = array('id');
}
class Section extends BaseModel {
    // [...]
}

$my_user = User::get(3);
$my_user->name = 'Jean';

$other_user = User::get(24);
$other_user->name = 'Paul';

$my_user->save();
$other_user->save();

$my_section = Section::get('apropos');
$my_section->delete();

Obviously, this is not the behavior I was expecting (although the actual behavior also makes sense).. So my question is if you guys know of a mean to get, in the parent class, the name of child class.

Answer

Jon47 picture Jon47 · Jul 22, 2009

You don't need to wait for PHP 5.3 if you're able to conceive of a way to do this outside of a static context. In php 5.2.9, in a non-static method of the parent class, you can do:

get_class($this);

and it will return the name of the child class as a string.

i.e.

class Parent() {
    function __construct() {
        echo 'Parent class: ' . get_class() . "\n" . 'Child class: ' . get_class($this);
    }
}

class Child() {
    function __construct() {
        parent::construct();
    }
}

$x = new Child();

this will output:

Parent class: Parent
Child class: Child

sweet huh?