How to connect to database using PDO in multiple classes? - php

Question

I have multiple classes and most of them need to connect to database,
How can I set PDO options/host/dbname etc only once and then use it in every class while having the following in mind:
I don't want to wrap PDO
I need to close the PDO connection after each query ($db=null), so I simply cannot just use $db = new PDO(...) and then pass $db to my classes
I want to skip having this in every class that needs to connect to the database:
<?php
$dsn = "mysql:host=$host;dbname=$db;charset=$charset";
$options = [
PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
PDO::ATTR_EMULATE_PREPARES => false,
];
try {
$pdo = new PDO($dsn, $user, $pass, $options);
} catch (\PDOException $e) {
throw new \PDOException($e->getMessage(), (int)$e->getCode());
}

Answer 1

If you want complete control over opening and closing connections then I suggest we only centralise the $dsn, $user, $pass and $options variables. I'm assuming there are also variables like $host, $db and $charset which you did not reveal to us but lets add them.
Lets call this file global_db.php:
<?php
$host = "127.0.0.1";
$db = "mydb";
$charset = "UTF-8";
$user = "root";
$pass = "";
$dsn = "mysql:host=$host;dbname=$db;charset=$charset";
$options = [
PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
PDO::ATTR_EMULATE_PREPARES => false,
];
That looks like we have all the goods there, keep in mind I am not testing this so we might get a syntax error or two.
Now in our classes or other php files where we want to open a connection.
Lets call this page fooClass.php
<?php
require_once 'global_db.php';
class FooClass {
public function __construct() {
try {
$pdo = new PDO(
$GLOBALS['dsn'],
$GLOBALS['user'],
$GLOBALS['pass'],
$GLOBALS['options']);
} catch (\PDOException $e) {
throw new \PDOException($e->getMessage(), (int)$e->getCode());
}
}
}
That should do the trick or at least give you a general idea on where to go from here on your own route. There are many other ways to accomplish similar but no need to overcomplicate things.
nJoy!