Do not act as a route result observer

This patch updates the `UrlHelper` such that it no longer acts as a route result observer. The `UrlHelperMiddleware` was updated to look for the `RouteResult` attribute, and, if present, inject the `UrlHelper` via its `setRouteResult()` property. These changes: - are not backwards compatible, and will require a new major version. - require merging of zendframework/zend-expressive#270 for the middleware updates to work.
weierophinney · Jan 18, 2016 · 52b0f79 · 52b0f79
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diff --git a/README.md b/README.md
@@ -28,9 +28,11 @@ can recommend the following implementations:
 
 `Zend\Expressive\Helper\UrlHelper` provides the ability to generate a URI path
 based on a given route defined in the `Zend\Expressive\Router\RouterInterface`.
-If registered as a route result observer, and the route being used was also
-the one matched during routing, you can provide a subset of routing
-parameters, and any not provided will be pulled from those matched.
+The provided `Zend\Expressive\Helper\UrlHelperMiddleware` can look for a
+`Zend\Expressive\Router\RouteResult` request attribute, and, if present, inject
+the `UrlHelper` with it; when this occurs, if the route being used to generate
+a URI was also the one matched during routing, you can provide a subset of
+routing parameters, and any not provided will be pulled from those matched.
 
 In order to use the helper, you will need to instantiate it with the current
 `RouterInterface`. The factory `Zend\Expressive\Helper\UrlHelperFactory` has
@@ -76,14 +78,13 @@ return ['dependencies' => [
 
 For the helper to be useful, it must be injected with a
 `Zend\Expressive\Router\RouteResult`. To automate this, we provide a middleware
-class, `UrlHelperMiddleware`, which accepts the `UrlHelper` instance and a
-`Zend\Expressive\Router\RouteResultSubjectInterface` instance (typically a
-`Zend\Expressive\Application` instance); when invoked, it attaches the
-`UrlHelper` as a route result observer. To register this middleware, you
-will need to:
+class, `UrlHelperMiddleware`, which accepts the `UrlHelper` instance.
+When invoked, it looks for a `RouteResult` request attribute, and, if found,
+injects it into the `UrlHelper`. To register this middleware, you will need to:
 
 - Register the `UrlHelperMiddleware` as a service in your container.
-- Register the `UrlHelperMiddleware` as pre_routing pipeline middleware.
+- Register the `UrlHelperMiddleware` as middleware between the Expressive
+  routing and dispatch middleware.
 
 The following examples demonstrate registering the services.
 
@@ -108,19 +109,25 @@ $container->set(
 );
 ```
 
-To register the `UrlHelperMiddleware` as pre-routing pipeline middleware:
+To register the `UrlHelperMiddleware`:
 
 ```php
 use Zend\Expressive\Helper\UrlHelperMiddleware;
 
-// Do this early, before piping other middleware or routes:
+$app->pipeRoutingMiddleware();
 $app->pipe(UrlHelperMiddleware::class);
+$app->pipeDispatchMiddleware();
 
 // Or use configuration:
 // [
 //     'middleware_pipeline' => [
-//         'pre_routing' => [
-//             ['middleware' => UrlHelperMiddleware::class],
+//         'routing' => [
+//             'middleware' => [
+//                 Zend\Expressive\Container\ApplicationFactory::ROUTING_MIDDLEWARE,
+//                 UrlHelperMiddleware::class,
+//                 Zend\Expressive\Container\ApplicationFactory::DISPATCH_MIDDLEWARE,
+//             ],
+//             'priority' => 1,
 //         ],
 //     ],
 // ]
@@ -140,8 +147,13 @@ return [
         ],
     ],
     'middleware_pipeline' => [
-        'pre_routing' => [
-            ['middleware' => UrlHelperMiddleware::class],
+        'routing' => [
+            'middleware' => [
+                Zend\Expressive\Container\ApplicationFactory::ROUTING_MIDDLEWARE,
+                UrlHelperMiddleware::class,
+                Zend\Expressive\Container\ApplicationFactory::DISPATCH_MIDDLEWARE,
+            ],
+            'priority' => 1,
         ],
     ],
 ]
@@ -278,7 +290,7 @@ As such, you will need to:
 
 - Register the `ServerUrlHelper` as a service in your container.
 - Register the `ServerUrlMiddleware` as a service in your container.
-- Register the `ServerUrlMiddleware` as pre_routing pipeline middleware.
+- Register the `ServerUrlMiddleware` early in your middleware pipeline.
 
 The following examples demonstrate registering the services.
 
@@ -309,19 +321,24 @@ $container->set(
 );
 ```
 
-To register the `ServerUrlMiddleware` as pre-routing pipeline middleware:
+To register the `ServerUrlMiddleware` in your middleware pipeline:
 
 ```php
 use Zend\Expressive\Helper\ServerUrlMiddleware;
 
 // Do this early, before piping other middleware or routes:
 $app->pipe(ServerUrlMiddleware::class);
 
+/* ... */
+$app->pipeRoutingMiddleware();
+$app->pipeDispatchMiddleware();
+
 // Or use configuration:
 // [
 //     'middleware_pipeline' => [
-//         'pre_routing' => [
-//             ['middleware' => ServerUrlMiddleware::class],
+//         [
+//             'middleware' => ServerUrlMiddleware::class,
+//             'priority' => PHP_INT_MAX,
 //         ],
 //     ],
 // ]
@@ -341,8 +358,9 @@ return [
         ],
     ],
     'middleware_pipeline' => [
-        'pre_routing' => [
-            ['middleware' => ServerUrlMiddleware::class],
+        [
+            'middleware' => ServerUrlMiddleware::class,
+            'priority' => PHP_INT_MAX,
         ],
     ],
 ]
@@ -407,7 +425,7 @@ use Zend\Expressive\Helper\BodyParams\BodyParamsMiddleware;
 $app->pipe(BodyParamsMiddleware::class);
 ```
 
-or, if using Expressive, as pre_routing pipeline middleware:
+or, if using Expressive, as pipeline middleware:
 
 ```php
 // config/autoload/middleware-pipeline.global.php
@@ -424,11 +442,11 @@ return [
         ],
     ],
     'middleware_pipeline' => [
-        'pre_routing' => [
-            [ 'middleware' => Helper\BodyParams\BodyParamsMiddleware::class ],
-            /* ... */
+        [
+            'middleware' => Helper\BodyParams\BodyParamsMiddleware::class,
+            'priority' => 1000,
         ],
-        'post_routing' => [
+        'routing' => [
             /* ... */
         ],
     ],

diff --git a/src/Exception/MissingSubjectException.php b/src/Exception/MissingSubjectException.php
diff --git a/src/UrlHelper.php b/src/UrlHelper.php
@@ -11,9 +11,8 @@
 use Zend\Expressive\Router\Exception\RuntimeException as RouterException;
 use Zend\Expressive\Router\RouterInterface;
 use Zend\Expressive\Router\RouteResult;
-use Zend\Expressive\Router\RouteResultObserverInterface;
 
-class UrlHelper implements RouteResultObserverInterface
+class UrlHelper
 {
     /**
      * @var string
@@ -95,14 +94,11 @@ public function generate($route = null, array $params = [])
     }
 
     /**
-     * {@inheritDoc}
-     */
-    public function update(RouteResult $result)
-    {
-        $this->result = $result;
-    }
-
-    /**
+     * Inject a route result.
+     *
+     * When the route result is injected, the helper will use it to seed default
+     * parameters if the URL being generated is for the route that was matched.
+     *
      * @param RouteResult $result
      */
     public function setRouteResult(RouteResult $result)

diff --git a/src/UrlHelperMiddleware.php b/src/UrlHelperMiddleware.php
@@ -9,11 +9,10 @@
 
 use Psr\Http\Message\ResponseInterface;
 use Psr\Http\Message\ServerRequestInterface;
-use Zend\Expressive\Router\RouteResultSubjectInterface;
+use Zend\Expressive\Router\RouteResult;
 
 /**
- * Pipeline middleware for attaching a UrlHelper to a
- * RouteResultSubjectInterface instance.
+ * Pipeline middleware for injecting a UrlHelper with a RouteResult.
  */
 class UrlHelperMiddleware
 {
@@ -22,25 +21,18 @@ class UrlHelperMiddleware
      */
     private $helper;
 
-    /**
-     * @var RouteResultSubjectInterface
-     */
-    private $subject;
-
     /**
      * @param UrlHelper $helper
-     * @param RouteResultSubjectInterface $subject
      */
-    public function __construct(UrlHelper $helper, RouteResultSubjectInterface $subject)
+    public function __construct(UrlHelper $helper)
     {
         $this->helper = $helper;
-        $this->subject = $subject;
     }
 
     /**
-     * Attach the UrlHelper instance as an observer to the RouteResultSubjectInterface
+     * Inject the UrlHelper instance with a RouteResult, if present as a request attribute.
      *
-     * Attaches the helper, and then dispatches the next middleware.
+     * Injects the helper, and then dispatches the next middleware.
      *
      * @param ServerRequestInterface $request
      * @param ResponseInterface $response
@@ -49,7 +41,12 @@ public function __construct(UrlHelper $helper, RouteResultSubjectInterface $subj
      */
     public function __invoke(ServerRequestInterface $request, ResponseInterface $response, callable $next)
     {
-        $this->subject->attachRouteResultObserver($this->helper);
+        $result = $request->getAttribute(RouteResult::class, false);
+
+        if ($result instanceof RouteResult) {
+            $this->helper->setRouteResult($result);
+        }
+
         return $next($request, $response);
     }
 }
diff --git a/src/UrlHelperMiddlewareFactory.php b/src/UrlHelperMiddlewareFactory.php
@@ -8,8 +8,6 @@
 namespace Zend\Expressive\Helper;
 
 use Interop\Container\ContainerInterface;
-use Zend\Expressive\Application;
-use Zend\Expressive\Router\RouteResultSubjectInterface;
 
 class UrlHelperMiddlewareFactory
 {
@@ -20,8 +18,6 @@ class UrlHelperMiddlewareFactory
      * @return UrlHelperMiddleware
      * @throws Exception\MissingHelperException if the UrlHelper service is
      *     missing
-     * @throws Exception\MissingSubjectException if the
-     *     RouteResultSubjectInterface service is missing
      */
     public function __invoke(ContainerInterface $container)
     {
@@ -33,44 +29,6 @@ public function __invoke(ContainerInterface $container)
             ));
         }
 
-        $subjectService = $this->getSubjectService($container);
-
-        return new UrlHelperMiddleware(
-            $container->get(UrlHelper::class),
-            $container->get($subjectService)
-        );
-    }
-
-    /**
-     * Determine the name of the service returning the RouteResultSubjectInterface instance.
-     *
-     * Checks against:
-     *
-     * - RouteResultSubjectInterface
-     * - Application
-     *
-     * returning the first that is found in the container.
-     *
-     * If neither is found, raises an exception.
-     *
-     * @param ContainerInterface $container
-     * @return string
-     * @throws Exception\MissingSubjectException
-     */
-    private function getSubjectService(ContainerInterface $container)
-    {
-        if ($container->has(RouteResultSubjectInterface::class)) {
-            return RouteResultSubjectInterface::class;
-        }
-
-        if ($container->has(Application::class)) {
-            return Application::class;
-        }
-
-        throw new Exception\MissingSubjectException(sprintf(
-            '%s requires a %s service at instantiation; none found',
-            UrlHelperMiddleware::class,
-            UrlHelper::class
-        ));
+        return new UrlHelperMiddleware($container->get(UrlHelper::class));
     }
 }
diff --git a/test/UrlHelperMiddlewareFactoryTest.php b/test/UrlHelperMiddlewareFactoryTest.php
@@ -12,13 +12,10 @@
 use Interop\Container\ContainerInterface;
 use PHPUnit_Framework_TestCase as TestCase;
 use Prophecy\Prophecy\ObjectProphecy;
-use Zend\Expressive\Application;
 use Zend\Expressive\Helper\Exception\MissingHelperException;
-use Zend\Expressive\Helper\Exception\MissingSubjectException;
 use Zend\Expressive\Helper\UrlHelper;
 use Zend\Expressive\Helper\UrlHelperMiddleware;
 use Zend\Expressive\Helper\UrlHelperMiddlewareFactory;
-use Zend\Expressive\Router\RouteResultSubjectInterface;
 
 class UrlHelperMiddlewareFactoryTest extends TestCase
 {
@@ -34,33 +31,15 @@ public function injectContainer($name, $service)
         $this->container->get($name)->willReturn($service);
     }
 
-    public function testFactoryCreatesAndReturnsMiddlewareWhenHelperAndSubjectArePresentInContainer()
+    public function testFactoryCreatesAndReturnsMiddlewareWhenHelperIsPresentInContainer()
     {
         $helper = $this->prophesize(UrlHelper::class)->reveal();
-        $subject = $this->prophesize(RouteResultSubjectInterface::class)->reveal();
         $this->injectContainer(UrlHelper::class, $helper);
-        $this->injectContainer(RouteResultSubjectInterface::class, $subject);
 
         $factory = new UrlHelperMiddlewareFactory();
         $middleware =$factory($this->container->reveal());
         $this->assertInstanceOf(UrlHelperMiddleware::class, $middleware);
         $this->assertAttributeSame($helper, 'helper', $middleware);
-        $this->assertAttributeSame($subject, 'subject', $middleware);
-    }
-
-    public function testFactoryCreatesAndReturnsMiddlewareWhenHelperAndApplicationArePresentInContainer()
-    {
-        $helper = $this->prophesize(UrlHelper::class)->reveal();
-        $subject = $this->prophesize(RouteResultSubjectInterface::class)->reveal();
-        $this->injectContainer(UrlHelper::class, $helper);
-        $this->container->has(RouteResultSubjectInterface::class)->willReturn(false);
-        $this->injectContainer(Application::class, $subject);
-
-        $factory = new UrlHelperMiddlewareFactory();
-        $middleware =$factory($this->container->reveal());
-        $this->assertInstanceOf(UrlHelperMiddleware::class, $middleware);
-        $this->assertAttributeSame($helper, 'helper', $middleware);
-        $this->assertAttributeSame($subject, 'subject', $middleware);
     }
 
     public function testFactoryRaisesExceptionWhenContainerDoesNotContainHelper()
@@ -74,14 +53,4 @@ public function testFactoryRaisesExceptionWhenContainerDoesNotContainHelper()
         $this->setExpectedException(MissingHelperException::class);
         $middleware =$factory($this->container->reveal());
     }
-
-    public function testFactoryRaisesExceptionWhenContainerDoesNotContainSubject()
-    {
-        $this->injectContainer(UrlHelper::class, $this->prophesize(UrlHelper::class));
-        $this->container->has(RouteResultSubjectInterface::class)->willReturn(false);
-        $this->container->has(Application::class)->willReturn(false);
-        $factory = new UrlHelperMiddlewareFactory();
-        $this->setExpectedException(MissingSubjectException::class);
-        $middleware =$factory($this->container->reveal());
-    }
 }