Middleware ========== Silex allows you to run code, that changes the default Silex behavior, at different stages during the handling of a request through *middleware*: * *Application middleware* is triggered independently of the current handled request; * *Route middleware* is triggered when its associated route is matched. Application Middleware ---------------------- Application middleware is only run for the "master" Request. Before Middleware ~~~~~~~~~~~~~~~~~ A *before* application middleware allows you to tweak the Request before the controller is executed:: $app->before(function (Request $request, Application $app) { // ... }); By default, the middleware is run after the routing and the security. If you want your middleware to be run even if an exception is thrown early on (on a 404 or 403 error for instance), then, you need to register it as an early event:: $app->before(function (Request $request, Application $app) { // ... }, Application::EARLY_EVENT); In this case, the routing and the security won't have been executed, and so you won't have access to the locale, the current route, or the security user. .. note:: The before middleware is an event registered on the Symfony *request* event. After Middleware ~~~~~~~~~~~~~~~~ An *after* application middleware allows you to tweak the Response before it is sent to the client:: $app->after(function (Request $request, Response $response) { // ... }); .. note:: The after middleware is an event registered on the Symfony *response* event. Finish Middleware ~~~~~~~~~~~~~~~~~ A *finish* application middleware allows you to execute tasks after the Response has been sent to the client (like sending emails or logging):: $app->finish(function (Request $request, Response $response) { // ... // Warning: modifications to the Request or Response will be ignored }); .. note:: The finish middleware is an event registered on the Symfony *terminate* event. Route Middleware ---------------- Route middleware is added to routes or route collections and it is only triggered when the corresponding route is matched. You can also stack them:: $app->get('/somewhere', function () { // ... }) ->before($before1) ->before($before2) ->after($after1) ->after($after2) ; Before Middleware ~~~~~~~~~~~~~~~~~ A *before* route middleware is fired just before the route callback, but after the *before* application middleware:: $before = function (Request $request, Application $app) { // ... }; $app->get('/somewhere', function () { // ... }) ->before($before); After Middleware ~~~~~~~~~~~~~~~~ An *after* route middleware is fired just after the route callback, but before the application *after* application middleware:: $after = function (Request $request, Response $response, Application $app) { // ... }; $app->get('/somewhere', function () { // ... }) ->after($after); Middleware Priority ------------------- You can add as much middleware as you want, in which case they are triggered in the same order as you added them. You can explicitly control the priority of your middleware by passing an additional argument to the registration methods:: $app->before(function (Request $request) { // ... }, 32); As a convenience, two constants allow you to register an event as early as possible or as late as possible:: $app->before(function (Request $request) { // ... }, Application::EARLY_EVENT); $app->before(function (Request $request) { // ... }, Application::LATE_EVENT); Short-circuiting the Controller ------------------------------- If a *before* middleware returns a ``Response`` object, the request handling is short-circuited (the next middleware won't be run, nor the route callback), and the Response is passed to the *after* middleware right away:: $app->before(function (Request $request) { // redirect the user to the login screen if access to the Resource is protected if (...) { return new RedirectResponse('/login'); } }); .. note:: A ``RuntimeException`` is thrown if a before middleware does not return a Response or ``null``.