Question

I’ve got a PHP project with many classes, and a PDO Wrapper class that I got off the web that seems pretty good:

http://code.google.com/p/php-pdo-wrapper-class/

My classes look like this now:

class product {
__constructor($id = 0) {
//mysql_query and store the product row in $this->row;
}

edit($array) {
//another obvious mysql_query...
}

So they’re very simple and I want to move all the mysql_query’s to PDO for security. I’ve got the variable:

$db = new pdo('localhost', 'user', 'pass');

Working correctly defined in the top line of my include file, before the classes. However, I don’t want to have to write:

global $db;

At the start of every function. I considered changing the __construct() function to be something more like:

__construct($id = 0, $db = null) {
$this->db = $db;
}

And then referencing from there, but the problem with that is that I then have to change every constructor in my whole website. Is there a way to solve this such that I am able to do the minuimum amount of editing the already existing code?

Answer 1

Make all your model classes inherit from a base model class, then define a static variable $db in your base class, and use it in the inherited classes.

class BaseModel {
  public static $db = NULL;
}

class UserModel extends BaseModel {
  public function create() {
    echo "Use the static variable: " . static::$db . "\n";
  }
}

BaseModel::$db = "new PDO object";
UserModel::create();

Outputs

Use the static variable: new PDO object