PHP - Passing DB Connection to Various Classes

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?

user1549550 · Accepted Answer · 2012-08-05 12:38:43Z

2

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

answered Aug 5, 2012 at 12:38

user1549550

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3 Comments

zerkms Over a year ago

It's not better than global variables

user1549550 Over a year ago

It's better in a sense that you don't have to say global $db inside of every function, and it's only "global" in BaseModel and its descendants rather than everywhere.

Andreas Christodoulou Over a year ago

This appears better in that I would only have to make a tiny "BaseModel" class and then type "extends BaseModel" at the end of ten class files, which would make it essentially backwards compatible while I change all the database calls over. Thanks!

pooria · Accepted Answer · 2012-08-05 12:36:00Z

0

as you said there is a PDO class so in every other classes easily you can make an instance of your PDO class. first include the PDO class in anywhere you need

require_once'/PDOclass.php';

then make instances

$a=new PDAclass;

answered Aug 5, 2012 at 12:36

pooria

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Comments

Tomer · Accepted Answer · 2012-08-05 12:37:20Z

0

You say the $db is defined in your include file. so just include the file and you'll have access to that parameter.

answered Aug 5, 2012 at 12:37

Tomer

17.9k16 gold badges82 silver badges139 bronze badges

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