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How to Properly Use a PDO Connection Across Multiple Classes in PHP?
How to Properly Use a PDO Connection Across Multiple Classes in PHP?
Dec 21, 2024 am 12:50 AM
How to Use PDO Connection in Other Classes?
Understanding the Puzzling Error
An error message stating "Uncaught Error: Call to undefined method Database::prepare()" may arise when attempting to use a PDO connection in a separate class. This error stems from a misunderstanding of how object-oriented programming (OOP) interconnects objects.
Resolving the Issue
1. Rethink Your Database Class:
The existing Database class serves no meaningful purpose. Instead, focus on creating a wrapper class if it extends PDO's functionality.
2. Establish a Central Database Connection:
Instantiate a standalone $db object using PDO or your enhanced database class. This single connection will serve as the cornerstone for all future database activities.
3. Pass the Connection as a Constructor Parameter:
Every class requiring database access should receive the $db connection as a constructor argument. This approach guarantees seamless access to the database throughout your entire application.
A Comprehensive Example
Consider the following improved codebase:
database.php:
$host = '127.0.0.1';
$db = 'test';
$user = 'root';
$pass = '';
$charset = 'utf8';
$dsn = "mysql:host=$host;dbname=$db;charset=$charset";
$opt = [
\PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION,
\PDO::ATTR_DEFAULT_FETCH_MODE => \PDO::FETCH_ASSOC,
\PDO::ATTR_EMULATE_PREPARES => false,
];
$pdo = new \PDO($dsn, $user, $pass, $opt);
user.php:
class User {
/* Properties */
private $conn;
/* Get database access */
public function __construct(\PDO $pdo) {
$this->conn = $pdo;
}
/* List all users */
public function getUsers() {
return $this->conn->query("SELECT username, usermail FROM user")->fetchAll();
}
}
app.php:
include 'database.php';
$user = new User($pdo);
$list = $user->getUsers();
foreach($list as $test) {
echo $test["username"],"\n";
}
This refined codebase exemplifies the correct usage of PDO connections in multiple classes, ensuring error-free operation and elegant coding practices.
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