Slim 4: PHP’s microframework

Rob Allen, April 2020

The C in MVC Rob Allen ~ @akrabat

Slim Framework • • • • Created by Josh Lockhart (phptherightway.com) PSR-7 Request and Response objects PSR-15 Middleware and Request Handlers PSR-11 DI container support Rob Allen ~ @akrabat

Hello world use … $app = AppFactory::create(); $app->get( ‘/ping’, function (Request $request, Response $response) { $response->getBody()->write(json_encode([‘ack’ => time()])); return $response->withHeader(‘Content-Type’, ‘application/json’); }); $app->run(); Rob Allen ~ @akrabat

Hello world use … $app = AppFactory::create(); // Init $app->get( ‘/ping’, function (Request $request, Response $response) { $response->getBody()->write(json_encode([‘ack’ => time()])); return $response->withHeader(‘Content-Type’, ‘application/json’); }); $app->run(); // Run Rob Allen ~ @akrabat

Hello world use … $app = AppFactory::create(); $app->get( // Method ‘/ping’, function (Request $request, Response $response) { $response->getBody()->write(json_encode([‘ack’ => time()])); return $response->withHeader(‘Content-Type’, ‘application/json’); }); $app->run(); Rob Allen ~ @akrabat

Hello world use … $app = AppFactory::create(); $app->get( ‘/ping’, // Pattern function (Request $request, Response $response) { $response->getBody()->write(json_encode([‘ack’ => time()])); return $response->withHeader(‘Content-Type’, ‘application/json’); }); $app->run(); Rob Allen ~ @akrabat

Hello world use … $app = AppFactory::create(); $app->get( ‘/ping’, function (Request $request, Response $response) { // Handler $response->getBody()->write(json_encode([‘ack’ => time()])); return $response->withHeader(‘Content-Type’, ‘application/json’); }); $app->run(); Rob Allen ~ @akrabat

Hello world $ curl -i http://localhost:8888/ping HTTP/1.1 200 OK Host: localhost:8888 Connection: close Content-Type: application/json { “ack”:1570046120 } Rob Allen ~ @akrabat

PSR-7 is the foundation Rob Allen ~ @akrabat

It’s all about HTTP Request: {METHOD} {URI} HTTP/1.1 Header: value1,value2 Another-Header: value Message body Rob Allen ~ @akrabat

It’s all about HTTP Response: HTTP/1.1 {STATUS_CODE} {REASON_PHRASE} Header: value Message body Rob Allen ~ @akrabat

PSR 7 OO interfaces to model HTTP • • • • RequestInterface (& ServerRequestInterface) ResponseInterface UriInterface UploadedFileInterface Rob Allen ~ @akrabat

Key feature 1: Immutability Request, Response, Uri & UploadFile are immutable $uri = new Uri(‘https://api.joind.in/v2.1/events’); $uri2 = $uri->withQuery(‘?filter=upcoming’); $uri3 = $uri->withQuery(‘?filter=cfp’); Rob Allen ~ @akrabat

Key feature 2: Streams Message bodies are streams $body = new Stream(); $body->write(‘<p>Hello’); $body->write(‘World</p>’); $response = (new Response()) ->withStatus(200, ‘OK’) ->withHeader(‘Content-Type’, ‘application/header’) ->withBody($body); Rob Allen ~ @akrabat

I write APIs so let’s talk in that context! Rob Allen ~ @akrabat

A good API framework • Understands HTTP methods • Can receive data in various formats • Has useful error reporting Rob Allen ~ @akrabat

HTTP verbs Rob Allen ~ @akrabat

HTTP methods Method GET PUT DELETE POST PATCH Used for Retrieve data Change data Delete data Change data Update data Idempotent? Yes Yes Yes No No Rob Allen ~ @akrabat

Routing HTTP methods in Slim // specific HTTP methods map to methods on $app $app->get(‘/games’, ListGamesHandler::class); $app->post(‘/games’, CreateGameHandler::class); // routing multiple HTTP methods $app->any(‘/games’, GamesHandler::class); $app->map([‘GET’, ‘POST’], ‘/games’, GamesHandler::class); Rob Allen ~ @akrabat

Dynamic routes $app->get(‘/games/{id}’, function($request, $response) { $id = $request->getAttribute(‘id’); $games = $this->gameRepository->loadById($id); $body = json_encode([‘game’ => $game]); $response->getBody()->write($body); $response = $response->withHeader( ‘Content-Type’, ‘application/json’); return $response; }); Rob Allen ~ @akrabat

It’s just Regex // numbers only $app->get(‘/games/{id:\d+}’, $callable); // optional segments $app->get(‘/games[/{id:\d+}]’, $callable); $app->get(‘/news[/{y:\d{4}}[/{m:\d{2}}]]’, $callable); Rob Allen ~ @akrabat

Invalid HTTP request methods If the HTTP method is not supported, return the 405 status code $ http —json PUT http://localhost:8888/ping HTTP/1.1 405 Method Not Allowed Allow: GET Connection: close Content-Length: 53 Content-type: application/json Host: localhost:8888 { “message”: “Method not allowed. Must be one of: GET” } Rob Allen ~ @akrabat

Incoming data Rob Allen ~ @akrabat

Content-Type handling The Content-Type header specifies the format of the incoming data $ curl http://localhost:8888/games \ -H “Content-Type: application/json” \ -d ‘{“player1”: “Rob”, “player2”: “Jon”}’ Rob Allen ~ @akrabat

Read with getBody() $app->post(‘/games’, function ($request, $response) { $data = $request->getBody(); $response->getBody()->write(print_r($data, true)); return $response; } ); Output: ‘{“player1”: “Rob”, “player2”: “Jon”}’ Rob Allen ~ @akrabat

Read with getParsedBody() Add Slim’s body-parsing middleware to your app: $app->addBodyParsingMiddleware(); Use in your handler: $app->post(‘/games’, function ($request, $response) { $data = $request->getParsedBody(); return $response->write(print_r($data, true)); } ); Rob Allen ~ @akrabat

Read with getParsedBody() $ curl -H “Content-Type: application/json” \ -H “Content-Type: application/json” \ -d ‘{“player1”: “Rob”, “player2”: “Jon”}’ Output: Array ( [player1] => Rob, [player2] => Jon ) Rob Allen ~ @akrabat

This also works with XML $ curl “http://localhost:8888/games” \ -H “Content-Type: application/xml” \ -d “<game><player1>Rob</player1><player2>Jon</player2></game>” Output: Array ( [player1] => Rob, [player2] => Jon ) Rob Allen ~ @akrabat

And form data curl “http://localhost:8888/games” \ -H “Content-Type: application/x-www-form-urlencoded” \ -d “player1=Rob’ -d ‘player2=Jon” Output: Array ( [player1] => Rob, [player2] => Jon ) Rob Allen ~ @akrabat

addBodyParsingMiddleware() ? Rob Allen ~ @akrabat

Middleware Middleware is code that exists between the request and response, and which can take the incoming request, perform actions based on it, and either complete the response or pass delegation on to the next middleware in the queue. Matthew Weier O’Phinney Rob Allen ~ @akrabat

Middleware Take a request, return a response Rob Allen ~ @akrabat

Middleware LIFO stack: $app->add(ValidationMiddleware::class); $app->add(AuthMiddleware::class); $app->add(AuthMiddleware::class); $app->addBodyParsingMiddleware(); $app->addErrorMiddleware(true, true, true); Rob Allen ~ @akrabat

PSR-15 MiddlewareInterface namespace Psr\Http\Server; use Psr\Http\Message\ResponseInterface; use Psr\Http\Message\ServerRequestInterface; interface MiddlewareInterface { public function process( ServerRequestInterface $request, RequestHandlerInterface $handler ) : ResponseInterface; } Rob Allen ~ @akrabat

PSR-15 MiddlewareInterface namespace Psr\Http\Server; use Psr\Http\Message\ResponseInterface; use Psr\Http\Message\ServerRequestInterface; interface MiddlewareInterface { public function process( ServerRequestInterface $request, RequestHandlerInterface $handler ) : ResponseInterface; } Rob Allen ~ @akrabat

PSR-15 MiddlewareInterface namespace Psr\Http\Server; use Psr\Http\Message\ResponseInterface; use Psr\Http\Message\ServerRequestInterface; interface MiddlewareInterface { public function process( ServerRequestInterface $request, RequestHandlerInterface $handler ) : ResponseInterface; } Rob Allen ~ @akrabat

PSR-15 MiddlewareInterface namespace Psr\Http\Server; use Psr\Http\Message\ResponseInterface; use Psr\Http\Message\ServerRequestInterface; interface MiddlewareInterface { public function process( ServerRequestInterface $request, RequestHandlerInterface $handler ) : ResponseInterface; } Rob Allen ~ @akrabat

TimerMiddleware class TimerMiddleware implements MiddlewareInterface { public function process($request, $handler) { $start = microtime(true); $response = $handler->handle($request); $taken = microtime(true) - $start; return $response->withHeader(‘Time-Taken’, $taken); } } Rob Allen ~ @akrabat

TimerMiddleware class TimerMiddleware implements MiddlewareInterface { public function process($request, $handler) { $start = microtime(true); $response = $handler->handle($request); $taken = microtime(true) - $start; return $response->withHeader(‘Time-Taken’, $taken); } } Rob Allen ~ @akrabat

TimerMiddleware class TimerMiddleware implements MiddlewareInterface { public function process($request, $handler) { $start = microtime(true); $response = $handler->handle($request); $taken = microtime(true) - $start; return $response->withHeader(‘Time-Taken’, $taken); } } Rob Allen ~ @akrabat

TimerMiddleware class TimerMiddleware implements MiddlewareInterface { public function process($request, $handler) { $start = microtime(true); $response = $handler->handle($request); $taken = microtime(true) - $start; return $response->withHeader(‘Time-Taken’, $taken); } } Rob Allen ~ @akrabat

TimerMiddleware class TimerMiddleware implements MiddlewareInterface { public function process($request, $handler) { $start = microtime(true); $response = $handler->handle($request); $taken = microtime(true) - $start; return $response->withHeader(‘Time-Taken’, $taken); } } Rob Allen ~ @akrabat

Route Handlers The other half of PSR-15! Rob Allen ~ @akrabat

Route Handlers Any callable! $app->add(‘/ping’, $app->add(‘/ping’, $app->add(‘/ping’, $app->add(‘/ping’, $app->add(‘/ping’, function ($request, $response) { … }); [‘PingController’, ‘aStaticFunction’]); [new PingController(), ‘aFunction’]); PingController::class.’:pingAction’); PingHander::class); Rob Allen ~ @akrabat

Use this one $app->add(‘/ping’, PingHandler::class); Rob Allen ~ @akrabat

PSR-15 RequestHandlerInterface namespace Psr\Http\Server; use Psr\Http\Message\ResponseInterface; use Psr\Http\Message\ServerRequestInterface; interface RequestHandlerInterface { public function handle( ServerRequestInterface $request ): ResponseInterface; } Rob Allen ~ @akrabat

PSR-15 RequestHandlerInterface namespace Psr\Http\Server; use Psr\Http\Message\ResponseInterface; use Psr\Http\Message\ServerRequestInterface; interface RequestHandlerInterface { public function handle( ServerRequestInterface $request ): ResponseInterface; } Rob Allen ~ @akrabat

PSR-15 RequestHandlerInterface namespace Psr\Http\Server; use Psr\Http\Message\ResponseInterface; use Psr\Http\Message\ServerRequestInterface; interface RequestHandlerInterface { public function handle( ServerRequestInterface $request ): ResponseInterface; } Rob Allen ~ @akrabat

PSR-15 RequestHandlerInterface namespace Psr\Http\Server; use Psr\Http\Message\ResponseInterface; use Psr\Http\Message\ServerRequestInterface; interface RequestHandlerInterface { public function handle( ServerRequestInterface $request ): ResponseInterface; } Rob Allen ~ @akrabat

PingHandler use use use use Psr\Http\Message\ResponseInterface; Psr\Http\Message\ServerRequestInterface as Request; Psr\Http\Server\RequestHandlerInterface; Slim\Psr7\Response; class PingHandler implements RequestHandlerInterface { public function handle(Request $request): ResponseInterface { $response = new Response(); $response->getBody()->write(json_encode([‘ack’ => time()]); return $response; } } Rob Allen ~ @akrabat

PingHandler use use use use Psr\Http\Message\ResponseInterface; Psr\Http\Message\ServerRequestInterface as Request; Psr\Http\Server\RequestHandlerInterface; Slim\Psr7\Response; class PingHandler implements RequestHandlerInterface { public function handle(Request $request): ResponseInterface { $response = new Response(); $response->getBody()->write(json_encode([‘ack’ => time()]); return $response; } } Rob Allen ~ @akrabat

PingHandler use use use use Psr\Http\Message\ResponseInterface; Psr\Http\Message\ServerRequestInterface as Request; Psr\Http\Server\RequestHandlerInterface; Slim\Psr7\Response; class PingHandler implements RequestHandlerInterface { public function handle(Request $request): ResponseInterface { $response = new Response(); $response->getBody()->write(json_encode([‘ack’ => time()]); return $response; } } Rob Allen ~ @akrabat

PingHandler use use use use Psr\Http\Message\ResponseInterface; Psr\Http\Message\ServerRequestInterface as Request; Psr\Http\Server\RequestHandlerInterface; Slim\Psr7\Response; class PingHandler implements RequestHandlerInterface { public function handle(Request $request): ResponseInterface { $response = new Response(); $response->getBody()->write(json_encode([‘ack’ => time()]); return $response; } } Rob Allen ~ @akrabat

When things go wrong Rob Allen ~ @akrabat

Error handling • Internal logging • Rendering for output Rob Allen ~ @akrabat

Injecting a logger More PSRs! 11 & 3 Rob Allen ~ @akrabat

PSR-11: Container interface The goal set by ContainerInterface is to standardize how frameworks and libraries make use of a container to obtain objects and parameters https://www.php-fig.org/psr/psr-11/ Rob Allen ~ @akrabat

PSR-3: Logger interface The main goal is to allow libraries to receive a Psr\Log\LoggerInterface object and write logs to it in a simple and universal way https://www.php-fig.org/psr/psr-3/ Rob Allen ~ @akrabat

Configure PHP-DI $containerBuilder = new ContainerBuilder(); $containerBuilder->addDefinitions([ // Factory for a PSR-3 logger LoggerInterface::class => function (ContainerInterface $c) { $logger = new Logger($settings[‘name’]); $logger->pushHandler(new ErrorLogHandler()); return $logger; }, ]); AppFactory::setContainer($containerBuilder->build()); $app = AppFactory::create(); Rob Allen ~ @akrabat

Configure PHP-DI $containerBuilder = new ContainerBuilder(); $containerBuilder->addDefinitions([ // Factory for a PSR-3 logger LoggerInterface::class => function (ContainerInterface $c) { $logger = new Logger($settings[‘name’]); $logger->pushHandler(new ErrorLogHandler()); return $logger; }, ]); AppFactory::setContainer($containerBuilder->build()); $app = AppFactory::create(); Rob Allen ~ @akrabat

Configure PHP-DI $containerBuilder = new ContainerBuilder(); $containerBuilder->addDefinitions([ // Factory for a PSR-3 logger LoggerInterface::class => function (ContainerInterface $c) { $logger = new Logger($settings[‘name’]); $logger->pushHandler(new ErrorLogHandler()); return $logger; }, ]); AppFactory::setContainer($containerBuilder->build()); $app = AppFactory::create(); Rob Allen ~ @akrabat

Configure PHP-DI $containerBuilder = new ContainerBuilder(); $containerBuilder->addDefinitions([ // Factory for a PSR-3 logger LoggerInterface::class => function (ContainerInterface $c) { $logger = new Logger($settings[‘name’]); $logger->pushHandler(new ErrorLogHandler()); return $logger; }, ]); AppFactory::setContainer($containerBuilder->build()); $app = AppFactory::create(); Rob Allen ~ @akrabat

Configure PHP-DI $containerBuilder = new ContainerBuilder(); $containerBuilder->addDefinitions([ // Factory for a PSR-3 logger LoggerInterface::class => function (ContainerInterface $c) { $logger = new Logger($settings[‘name’]); $logger->pushHandler(new ErrorLogHandler()); return $logger; }, ]); AppFactory::setContainer($containerBuilder->build()); $app = AppFactory::create(); Rob Allen ~ @akrabat

Configure PHP-DI $containerBuilder = new ContainerBuilder(); $containerBuilder->addDefinitions([ // Factory for a PSR-3 logger LoggerInterface::class => function (ContainerInterface $c) { $logger = new Logger($settings[‘name’]); $logger->pushHandler(new ErrorLogHandler()); return $logger; }, ]); AppFactory::setContainer($containerBuilder->build()); $app = AppFactory::create(); Rob Allen ~ @akrabat

PHP-DI autowiring Just type-hint your constructor! class GetGameHandler implements RequestHandlerInterface { private $logger; public function __construct(LoggerInterface $logger) { $this->logger = $logger; } … Rob Allen ~ @akrabat

Logging class GetGameHandler implements RequestHandlerInterface { public function handle(Request $request): ResponseInterface this->logger->info(“Fetching game”, [‘id’ => $id]); try { $games = $this->gameRepository->loadById($id); } catch (NotFoundException $e) { throw new HttpNotFoundException($request, ‘Game not found’, $e); } … Rob Allen ~ @akrabat

Logging class GetGameHandler implements RequestHandlerInterface { public function handle(Request $request): ResponseInterface this->logger->info(“Fetching game”, [‘id’ => $id]); try { $games = $this->gameRepository->loadById($id); } catch (NotFoundException $e) { throw new HttpNotFoundException($request, ‘Game not found’, $e); } … Rob Allen ~ @akrabat

Rendering errors Rob Allen ~ @akrabat

Slim’s error handling Add Slim’s error handling middleware to render exceptions $displayDetails = true; $logErrors = true; $logErrorDetails = true; $app->addErrorMiddleware($displayDetails, $logErrors, $logErrorDetails); Rob Allen ~ @akrabat

Error rendering $ http -j DELETE http://localhost:8888/game HTTP/1.1 405 Method Not Allowed Allow: GET Content-type: application/json { “exception”: [ { “code”: 405, “file”: “…/Slim/Middleware/RoutingMiddleware.php”, “message”: “Method not allowed: Must be one of: GET”, “type”: “Slim\Exception\HttpMethodNotAllowedException” } ], “message”: “Method not allowed: Must be one of: GET” } Rob Allen ~ @akrabat

Raise your own use App\Model\GameNotFoundException; use Slim\Exception\HttpNotFoundException; use Slim\Exception\HttpInternalServerErrorException; public function handle(Request $request): ResponseInterface { $id = $request->getAttribute(‘id’); try { $game = $this->gameRepository->loadById($id); } catch (GameNotFoundException $e) { throw new HttpNotFoundException($request, ‘Game not found’, $e); } catch (\Exception $e) { throw new HttpInternalServerErrorException($request, ‘An unknown error occurred’, $e); } Rob Allen ~ @akrabat

Not found error use App\Model\GameNotFoundException; use Slim\Exception\HttpNotFoundException; use Slim\Exception\HttpInternalServerErrorException; public function handle(Request $request): ResponseInterface { $id = $request->getAttribute(‘id’); try { $games = $this->gameRepository->loadById($id); } catch (GameNotFoundException $e) { throw new HttpNotFoundException($request, ‘Game not found’, $e); } catch (\Exception $e) { throw new HttpInternalServerErrorException($request, ‘An unknown error occurred’, $e); } Rob Allen ~ @akrabat

Not found error $ http -j http://localhost:8888/games/1234 HTTP/1.1 404 Not Found Content-type: application/json { “message”: “Game not found” } (With $displayDetails = false) Rob Allen ~ @akrabat

Generic error use App\Model\GameNotFoundException; use Slim\Exception\HttpNotFoundException; use Slim\Exception\HttpInternalServerErrorException; public function handle(Request $request): ResponseInterface { $id = $request->getAttribute(‘id’); try { $games = $this->gameRepository->loadById($id); } catch (GameNotFoundException $e) { throw new HttpNotFoundException($request, ‘Game not found’, $e); } catch (\Exception $e) { throw new HttpInternalServerErrorException($request, ‘An unknown error occurred’, $e); } Rob Allen ~ @akrabat

Generic error $ http -j http://localhost:8888/games/abcd HTTP/1.1 500 Internal Server Error Content-type: application/json { “exception”: [ { “code”: 500, “file”: “…/src/Handler/GetGameHandler.php”, “line”: 43, “message”: “An unknown error occurred”, “type”: “Slim\Exception\HttpInternalServerErrorException” }, Rob Allen ~ @akrabat

{ “code”: 40, “file”: “…/lib/Assert/Assertion.php”, “line”: 2752, “message”: “Value “abcd” is not a valid integer.”, “type”: “Assert\InvalidArgumentException” } ], “message”: “An unknown error occurred” } (With $displayDetails = true) Rob Allen ~ @akrabat

To sum up Rob Allen ~ @akrabat

Resources • http://slimframework.com • https://akrabat.com/category/slim-framework/ • https://github.com/akrabat/slim4-rps-api • https://github.com/akrabat/slim4-starter Rob Allen ~ @akrabat

Thank you! Rob Allen - http://akrabat.com - @akrabat Rob Allen ~ @akrabat

Photo credits - The Fat Controller: HiT Entertainment - Foundation: https://www.flickr.com/photos/armchairbuilder/6196473431 - APIs: https://www.flickr.com/photos/ebothy/15723500675 - Verbs: https://www.flickr.com/photos/160866001@N07/45904136621/ - Incoming Data: https://www.flickr.com/photos/natspressoffice/13085089605 - Computer code: https://www.flickr.com/photos/n3wjack/3856456237/ - Road sign: https://www.flickr.com/photos/ell-r-brown/6804246004 - Car crash: EuroNCAP - Writing: https://www.flickr.com/photos/froderik/9355085596/ - Error screen: https://www.flickr.com/photos/thirdrail/18126260 - Rocket launch: https://www.flickr.com/photos/gsfc/16495356966 - Stars: https://www.flickr.com/photos/gsfc/19125041621 Rob Allen ~ @akrabat