Routing

Routing in Erlenmeyer follows the same philosophy as the rest of the framework: simplicity and clarity first.
You declare routes directly on the App instance — no separate route files or rigid structures required.

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How routing works

At its core, routing is managed by the App class.
Each route maps an HTTP method and a URI pattern to a callable handler:

$app->get('/hello', function (Request $req, Response $res) {
    $res->withText('Hello world!')->send();
});

Under the hood, routes are stored internally as regular expressions, allowing Erlenmeyer to support dynamic parameters and even fallback routes.

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Dynamic parameters

Parameters are enclosed in square brackets [], and are automatically converted into named regex groups:

$app->get('/users/[id]', function ($req, $res, $params) {
    $res->withJson(['id' => $params->id])->send();
});

You can use as many parameters as you need, and Erlenmeyer will map them into a $params object:

$app->get('/posts/[year]/[slug]', fn($req, $res, $p)
    => $res->withJson($p)->send());

Internally, /users/[id] becomes:

/^\/users\/([a-zA-Z0-9\.\-_]+)$/

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Route methods

You can register routes for any HTTP verb, or for multiple ones at once:

$app->get('/users', ...);
$app->post('/users', ...);
$app->put('/users/[id]', ...);
$app->delete('/users/[id]', ...);
$app->patch('/users/[id]', ...);

Or combine several in one call:

$app->match(['GET', 'POST'], '/contact', ...);
$app->any('/ping', ...); // handles all methods

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Redirects

Simple route redirection is built in:

$app->redirect('/old-home', '/new-home');
$app->redirect('/legacy', '/', permanent: true);

The second parameter defines the destination, and the optional permanent flag triggers a 301 redirect instead of 302.

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Fallbacks and 404s

If no route matches, Erlenmeyer will:

1. Try to serve a static file through the Assets manager (if configured);
2. Otherwise, call the 404 handler.

You can customize the 404 handler at any time:

$app->set404Handler(function ($req, $res) {
    $res->setStatusCode(404)->withHtml('<h1>Not found</h1>')->send();
});

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Middlewares

Each route can have its own middleware chain. A middleware receives a $next() callback to continue the execution flow:

$auth = function ($req, $res, $next, $params) {
    if ($req->getQueryParam('token') !== 'secret') {
        $res->withText('Unauthorized')->setStatusCode(401)->send();
        return;
    }
    $next($req, $res, new stdClass());
};

$app->get('/secure', fn($req, $res) => $res->withText('Welcome!')->send(), [$auth]);

You can also register global middlewares:

$app->addMiddleware($auth);

They will be applied to every route automatically.

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Under the hood

• The App class keeps an internal map of routes by method.
• Each route is stored as a regex pattern and a handler.
• When a request arrives, handle() loops through the registered routes, testing each pattern with preg_match.
• If a match is found, parameters are mapped into an object and passed to the handler.
• If none match, the fallback or 404 handler is invoked.

This simple mechanism allows Erlenmeyer to remain lightweight, predictable, and easy to debug.