activecollab / middlewarestack
Port of Slim's middleware stack implementation as a stand-alone package
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Requires
- php: >=5.6.0
- psr/http-message: ^1.0
Requires (Dev)
- friendsofphp/php-cs-fixer: ~1.0
- phpunit/phpunit: ~5.0
- zendframework/zend-diactoros: ^1.3
README
This package lets you build a stack of middlewares and run requests through them to their coresponding responses. Stack is Last In First Out stack (LIFO), meaning that middlewares that are added later are considered to be "outter" middlewares, and they are executed first.
Example:
$stack = new MiddlewareStack(); $stack->addMiddleware(function (ServerRequestInterface $request, ResponseInterface $response, callable $next = null) { // Route request to the contraoller, execute action, and encode action result to response if ($next) { $response = $next($request, $response); } return $response; }); $stack->addMiddleware(function (ServerRequestInterface $request, ResponseInterface $response, callable $next = null) { if (!user_is_authenticated($request)) { return $response->withStatus(403); // Break here if user is not authenticated } if ($next) { $response = $next($request, $response); } return $response; }); $request = new ServerRequest(); $response = $stack->process($request, new Response());
This example shows a simple authorization check prior to request being sent further down to routing, controller, and result encoding.
Error Handling
Stack exposes a way to handle exceptions (which extend \Exception
class) and PHP errors (which are \Throwable
, but don't extend \Exception
class, available in PHP7 and up):
$stack->setExceptionHandler(function (Exception $e, ServerRequestInterface $request, ResponseInterface $response) { $response = $response->withStatus(500, 'Exception: ' . $e->getMessage()); return $response; }); $stack->setPhpErrorHandler(function (Throwable $e, ServerRequestInterface $request, ResponseInterface $response) { $response = $response->withStatus(500, 'PHP error: ' . $e->getMessage()); return $response; });
Extension Points
You can use MiddlewareStack
implementation as is, or you can extend it to change its behaviour. There are two extra protected
methods that you can use to hook in your behaviour in the stack execution:
MiddlewareStack
is called in the middle of execution, as just another middleware. Override__invoke
method if you need to inject extra functionlity there (like routing, with per-route middleware stack for example),finalizeProcessing
is called prior to $response being returned byprocess
method. Override if you need to do something with response prior to returning it.
History
Most middleware implementations that we found in November 2016. assumed and did too much, being mini frameworks themselves - they anticipated routing, substacking etc.
Slim framework has a nice middleware stack implementation, but it was not available as a stand-alone component, something that we needed, so we decided to extract it.