Template-Muster: Logik und Darstellung trennen

Warum Logik und View trennen?

Das einfache Template-Muster

<?php
// --- LOGIC (top) ---
require 'config.php';
$userId = (int) ($_GET['id'] ?? 0);
$user   = getUserById($userId);
if (!$user) {
    http_response_code(404);
    require '404.php';
    exit;
}
$pageTitle = 'Profile: ' . $user['name'];

// --- VIEW (bottom) ---
require 'layout/header.php';
?>
<main>
    <h1><?= htmlspecialchars($user['name']) ?></h1>
</main>
<?php require 'layout/footer.php'; ?>

Controller- und View-Dateien trennen

// profile.php (controller)
<?php
require 'config.php';
$userId = (int) ($_GET['id'] ?? 0);
$user   = getUserById($userId);
$posts  = getPostsByUser($userId);

if (!$user) { require '404.php'; exit; }

require 'views/profile.view.php';

// views/profile.view.php (view) — only HTML and echoes
// No DB calls allowed here!

View-Daten vorbereiten

<?php
$user = getUserById($id);

$viewData = [
    'userName'   => htmlspecialchars($user['name']),
    'avatarUrl'  => $user['avatar'] ?? '/default.png',
    'joinedDate' => date('F Y', strtotime($user['created_at'])),
    'isAdmin'    => in_array('admin', $user['roles']),
];

extract($viewData);  // Makes $userName, $avatarUrl, etc.
require 'views/profile.view.php';

Template-Funktionsmuster

<?php
function render(string $view, array $data = []): void {
    extract($data);  // Create variables from array
    require __DIR__ . '/views/' . $view . '.php';
}

// Usage:
render('profile', [
    'name'   => $user['name'],
    'email'  => $user['email'],
]);

Template-Engine mit Ausgabepufferung

<?php
function renderToString(string $view, array $data = []): string {
    extract($data);
    ob_start();
    require __DIR__ . '/views/' . $view . '.php';
    return ob_get_clean();
}

$html = renderToString('email/welcome', ['name' => 'Alice']);
mail($to, 'Welcome!', $html, 'Content-Type: text/html');

Wann Sie eine Template-Engine verwenden sollten

Twig-Beispiel

<?php
// After: composer require twig/twig
$loader = new Twig\Loader\FilesystemLoader('/templates');
$twig   = new Twig\Environment($loader, ['cache' => '/tmp/twig']);

echo $twig->render('profile.html.twig', [
    'user'  => $user,
    'posts' => $posts,
]);

// profile.html.twig:
// <h1>{{ user.name }}</h1>  -- auto-escaped by default

MVC-Verzeichnisstruktur

project/
  controllers/
    UserController.php   -- handles request, calls model
  models/
    User.php             -- database queries
  views/
    users/
      profile.php        -- display only, no logic
  public/
    index.php            -- front controller (router)

Front-Controller-Muster

<?php
// public/index.php (front controller)
require __DIR__ . '/../vendor/autoload.php';

$uri    = parse_url($_SERVER['REQUEST_URI'], PHP_URL_PATH);
$routes = require '../routes.php';

if (isset($routes[$uri])) {
    [$controller, $action] = $routes[$uri];
    (new $controller)->$action();
} else {
    http_response_code(404);
    require '../views/404.php';
}

Single-Responsibility-Prinzip

Schnelltest

Zusammenfassung: Template-Muster