How Can I Manage PDO Connections Efficiently Across Multiple Classes in PHP?

Accessing PDO Connections in Multiple Classes

In object-oriented programming, proper encapsulation and separation of concerns are crucial. One of the key concepts is to avoid passing connections directly between classes. This can lead to tightly coupled code that is difficult to maintain and extend.

To address this issue, it's recommended to follow these best practices:

1. Centralized Connection Management

Create a single connection instance at the application level. This can be achieved by instantiating the PDO connection outside of any class and making it globally available.

2. Pass the Connection as a Constructor Parameter

Instead of having each class instantiate its own connection, pass the centralized connection instance as a constructor parameter to every class that requires database access. This ensures that the connection is securely and consistently passed throughout the application.

3. Example Code

Here's a revised example that follows these best practices:

// database.php
$host = '127.0.0.1';
$db = 'test';
$user = 'root';
$pass = '';
$dsn = "mysql:host=$host;dbname=$db";
$pdo = new PDO($dsn, $user, $pass);

// user.php
class User {
    public function __construct(\PDO $pdo) {
        $this->conn = $pdo;
    }

    public function getUsers() {
        $stmt = $this->conn->prepare("SELECT username, usermail FROM user");
        $stmt->execute();
        return $stmt->fetchAll();
    }
}

// app.php
include 'database.php';
$user = new User($pdo);
$users = $user->getUsers();

foreach ($users as $user) {
    echo $user['username'] . "\n";
}

By following these guidelines, you can ensure that your application's database access is handled in a consistent and efficient manner, avoiding common pitfalls associated with direct connection passing.

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