Using a database class in my user class

Question

In my project I have a database class that I use to handle all the MySQL stuff. It connects to a database, runs queries, catches errors and closes the connection.

Now I need to create a members area on my site, and I was going to build a users class that would handle registration, logging in, password/username changes/resets and logging out. In this users class I need to use MySQL for obvious reasons... which is what my database class was made for.

But I'm confused as to how I would use my database class in my users class. Would I want to create a new database object for my user class and then have it close whenever a method in that class is finished? Or do I somehow make a 'global' database class that can be used throughout my entire script (if this is the case I need help with that, no idea what to do there.)

Thanks for any feedback you can give me.

Answer 1

Simple, 3 step process. 1/ Create a database object. 2/ Give it to your user class constructor. 3/ Use it in the user methods.

Little example.

File Database.class.php :

<?php
class Database{
  public function __construct(){
    // Connects to database for example.
  }

  public function query($sqlQuery){
    // Send a query to the database
  }
  [...]
}

In User.class.php :

<?php

class User{
  private $_db;
  public function __construct(Database $db){
    $this->_db = $db;
  }

  public function deleteUser(){
    $this->_db->query('DELETE FROM Users WHERE name = "Bobby"');
  }
}

Now, in userManager.php for example :

<?php
$db = new Database();
$user = new User($db);
// Say bye to Bobby :
$user->deleteUser();

If you want the current trendy name of this old technique, google "Dependency Injection". The Singleton pattern in php will fade away soon.