Slim 4: PHP’s Microframework

A presentation at PHP MiNDS in March 2020 in Nottingham, UK by Rob Allen

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Rob Allen, March 2020

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The C in MVC Rob Allen ~ @akrabat

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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

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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

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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

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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

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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

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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

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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

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PSR-7 is the foundation Rob Allen ~ @akrabat

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

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

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

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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

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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

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

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

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HTTP verbs Rob Allen ~ @akrabat

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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

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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

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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

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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

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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

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Incoming data Rob Allen ~ @akrabat

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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

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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

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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

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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

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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

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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

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addBodyParsingMiddleware() ? Rob Allen ~ @akrabat

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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

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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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

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

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

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PSR-15 RouteHandlerInterface 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

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PSR-15 RouteHandlerInterface 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

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PSR-15 RouteHandlerInterface 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

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PSR-15 RouteHandlerInterface 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

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

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

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

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

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When things go wrong Rob Allen ~ @akrabat

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

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

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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

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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

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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

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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

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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

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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

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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

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Rendering errors Rob Allen ~ @akrabat

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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

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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

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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

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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

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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

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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

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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

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{ “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

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To sum up Rob Allen ~ @akrabat

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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

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

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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