PHP — Sessions

Starting a session

<?php
session_start();

// Set session variable
$_SESSION['username'] = 'Alice';
$_SESSION['logged_in'] = true;

// Access session variable
echo $_SESSION['username'];
?>

Session operations

<?php
session_start();

// Check if set
if (isset($_SESSION['username'])) {
    echo "Welcome, " . $_SESSION['username'];
}

// Destroy session
session_unset();
session_destroy();
?>

Session with database

<?php
session_start();

// Login
function login(string $username, string $password): bool {
    // Verify credentials
    $valid = verifyCredentials($username, $password);
    if ($valid) {
        $_SESSION['user_id'] = getUserId($username);
        $_SESSION['username'] = $username;
        return true;
    }
    return false;
}

// Check login
function isLoggedIn(): bool {
    return isset($_SESSION['user_id']);
}

// Logout
function logout(): void {
    session_unset();
    session_destroy();
}
?>

Session configuration

<?php
// Set session cookie parameters
session_set_cookie_params([
    'lifetime' => 3600,
    'path' => '/',
    'domain' => 'example.com',
    'secure' => true,
    'httponly' => true,
    'samesite' => 'Strict'
]);

session_start();
?>

Mini Practice

Write PHP code that:

1. Starts a session and sets variables
2. Checks if a session variable exists
3. Destroys a session
4. Configures session cookie parameters

Up Next

In the next lesson, you'll learn about Cookies — working with cookies.