How to create global connection? - php

Question

I want create a global connection, so in the entire script I can access to a single object. Actually I made this class:
<?php
class Database {
private static $db;
private $connection;
private function __construct($conn) {
$this->connection = $conn;
$this->init();
}
private function init(){
// here the connection is going to execute
$host = $this->_connection['host'];
//etc...
}
function __destruct() {
$this->connection->close();
}
public static function getConnection($conn) {
if (self::$db == null) {
self::$db = new Database($conn);
}
return self::$db->connection;
}
}
?>
I pass the details of connection like this: $db = Database::getConnection($connection); Now $connection contains an array with the credentials access. Here no problem all working good. The main problem is that $db = Database::getConnection($connection); is called only when the index create the instance of the connection. My goal is call the $connection object in any models or controller, example:
class Model
{
function __construct()
{
$this->db = Database::getConnection();
}
}
how you can see I can't pass the connection parameter 'cause I want just use the connection previously established by the index.php call. How I can access to this connection without pass parameter?

Answer 1

You need to both make the $conn parameter optional and make sure it is passed on the first call:
public static function getConnection($conn=null) {
if (self::$db == null) {
if ($conn === null) {
throw new Exception('Can not initialize the database');
}
self::$db = new Database($conn);
}
return self::$db->connection;
}
Then you need to call the getConnection somewhere during the application start and pass the configuration to it.
After that you can use it without parameters.
If, by mistake, you don't configure the database, you'll have a clear error.

Answer 2

You could try this
public static function getConnection($conn = null) {
if (self::$db != null) {
return self::$db->connection;
}
//maybe add some validation here to ensure that the $conn value has been set
self::$db = new Database($conn);
return self::$db->connection;
}
or this works as well although it will throw an error if you don't set the $conn on the first call.
public static function getConnection($conn = null) {
if (self::$db == null && $conn) {
self::$db = new Database($conn);
}
return self::$db->connection;
}
It changes your logic a bit but should now work as you expect it to.
If the $conn is not supplied then it wont throw an error.