Tinkering with a Hal resource DTO, separating the framework from the app and content negotiation

index.php

<?php

namespace Demo {
    require __DIR__."/vendor/autoload.php";

    use Nocarrier\Hal;

    class Resource extends Hal {}

    class ResourceResponse
    {
        protected $resource;
        protected $code;

        public function __construct(Resource $resource, $code = 200)
        {
            $this->resource = $resource;
            $this->code = 200;
        }

        public function getResource() 
        {
            return $this->resource;
        }

        public function getCode()
        {
            return $this->code;
        }
    }

    class UserController
    {
        public function get($id)
        {
            $resource = new Resource("/user/" . $id, array(
                "name" => "Dave", // everybody's called Dave
            ));

            return new ResourceResponse($resource, 200);
        }
    }
}

namespace {

    use Silex\Application;
    use Symfony\Component\HttpFoundation\Response;
    use Symfony\Component\HttpKernel\Event\GetResponseForControllerResultEvent;
    use Symfony\Component\HttpKernel\KernelEvents;
    use Symfony\Component\HttpKernel\Exception\HttpException;
    use FOS\Rest\Util\FormatNegotiator;

    $app = new Application();
    $app['debug'] = true;

    $app['format_negotiator'] = $app->share(function() {
        return new FormatNegotiator;
    });

    /**
     * Content negotiating Resource to Response listener
     */
    $app->on(KernelEvents::VIEW, function(GetResponseForControllerResultEvent $event) use ($app) {

        $response = $event->getControllerResult();

        /**
         * If its not a resource, let other listeners handle it
         */
        if (!($response instanceof Demo\ResourceResponse)) {
            return;
        }

        $request = $event->getRequest();

        /**
         * This is an annoying prerequisite
         */
        $request->setFormat('json', array("application/hal+json", "application/json"));
        $request->setFormat('xml', array("application/hal+xml", "application/xml"));

        /**
         * Determine which format is best
         *
         * I think I'd prefer this to have methods to calculate the prefered 
         * mimetype and best format
         */
        $format = $app['format_negotiator']->getBestFormat($request, array(
            "json",
            "xml",
        ));

        /**
         * If we don't know what they want, bail
         */
        if (null === $format) {
            throw new HttpException(406, "No matching accepted Response format could be determined");
            return;
        }

        /**
         * Set the response
         */
        if ("xml" == $format) {
            $response = new Response(
                $response->getResource()->asXml(),
                $response->getCode(),
                array("Content-Type" => "application/hal+xml")
            );
        } else {
            $response = new Response(
                $response->getResource()->asJson(),
                $response->getCode(),
                array("Content-Type" => "application/hal+json")
            );
        }

        $event->setResponse($response);
    });

    /**
     * Routing
     */
    $app->get("/user/{id}", "Demo\UserController::get");

    $app->run();
}

Points to note

• The URLs need to be specific to the app layer, then transformed in the web layer?
• Need some way of binding acceptable mimetypes to the routes, so content negotiation can be done pre-cintroller, should check FOSRestBundle