code challenge 4 solution

Author: jschaedl

CODING-CHALLENGE-5.md

@@ -0,0 +1,27 @@
+# RESTful Webservices in Symfony
+
+## Coding Challenge 5 - Content Negotiation
+
+### Tasks
+
+- set the correct format option (JSON or XML) of the current Request
+- read the `Accept` request header and negotiate the content-type using Will Durand's negotiation library
+
+### Solution
+
+- require the willdurand/negotiation library: `composer require willdurand/negotiation`
+- create a `ContentNegotiator` class, use the `RequestStack` and implement a method to retrieve
+  the negotiated request format (`json` should be the default request format)
+- create a `RequestFormatListener`, subscribe on the `kernel.request` event (priority: 8) and
+  use the `ContentNegotiator` to set the request's request format
+- adjust all your Controllers, Normalizers and Data Transfer Objects to provide your representation of
+  your resources in the format accepted by the client
+
+#### Hints
+
+You can get the best fitting format by using:
+
+```
+$negotiator = new Negotiator();
+$acceptHeader = $negotiator->getBest($request->getAcceptableContentTypes(), self::ACCEPTED_CONTENT_TYPES);
+```

src/Pagination/AttendeeCollectionFactory.php

@@ -6,16 +6,24 @@
 
 use App\Repository\AttendeeRepository;
 use Doctrine\Bundle\DoctrineBundle\Repository\ServiceEntityRepositoryInterface;
+use Symfony\Component\Routing\Generator\UrlGeneratorInterface;
 
 final class AttendeeCollectionFactory extends PaginatedCollectionFactory
 {
     public function __construct(
-        private AttendeeRepository $attendeeRepository
+        private AttendeeRepository $attendeeRepository,
+        UrlGeneratorInterface $urlGenerator,
     ) {
+        parent::__construct($urlGenerator);
     }
 
     public function getRepository(): ServiceEntityRepositoryInterface
     {
         return $this->attendeeRepository;
     }
+
+    public function getRouteName(): string
+    {
+        return 'list_attendee';
+    }
 }

src/Pagination/PaginatedCollection.php

@@ -4,19 +4,30 @@
 
 namespace App\Pagination;
 
+use Symfony\Component\Serializer\Annotation\SerializedName;
+
 final class PaginatedCollection
 {
     private array $items;
     private int $total;
     private int $count;
 
+    private array $links;
+
     public function __construct(\Iterator $items, int $total)
     {
         $this->items = iterator_to_array($items);
         $this->total = $total;
         $this->count = \count($this->items);
     }
 
+    public function addLink(string $rel, string $href): self
+    {
+        $this->links[$rel]['href'] = $href;
+
+        return $this;
+    }
+
     public function getItems(): array
     {
         return $this->items;
@@ -31,4 +42,10 @@ public function getCount(): int
     {
         return $this->count;
     }
+
+    #[SerializedName('_links')]
+    public function getLinks(): array
+    {
+        return $this->links ?? [];
+    }
 }

src/Pagination/PaginatedCollectionFactory.php

@@ -6,27 +6,62 @@
 
 use Doctrine\Bundle\DoctrineBundle\Repository\ServiceEntityRepositoryInterface;
 use Doctrine\ORM\Tools\Pagination\Paginator;
+use Symfony\Component\Routing\Generator\UrlGeneratorInterface;
 
 abstract class PaginatedCollectionFactory
 {
+    public function __construct(
+        private UrlGeneratorInterface $urlGenerator
+    ) {
+    }
+
     abstract public function getRepository(): ServiceEntityRepositoryInterface;
 
+    abstract public function getRouteName(): string;
+
     public function create(int $page, int $size): PaginatedCollection
     {
-        $query = $this->getRepository()
-            ->createQueryBuilder('u')
+        $repository = $this->getRepository();
+
+        $query = $repository->createQueryBuilder('u')
             ->orderBy('u.id', 'asc')
             ->getQuery()
         ;
 
         $paginator = new Paginator($query);
         $total = count($paginator);
+        $pageCount = ceil($total / $size);
 
         $paginator
             ->getQuery()
             ->setFirstResult($size * ($page - 1))
-            ->setMaxResults($size);
+            ->setMaxResults($size)
+        ;
+
+        $paginatedCollection = new PaginatedCollection($paginator->getIterator(), $total);
+
+        $routeName = $this->getRouteName();
+
+        $paginatedCollection
+            ->addLink('self', $this->urlGenerator->generate($routeName, ['page' => $page, 'size' => $size]));
+
+        if (1 < $pageCount) {
+            $paginatedCollection
+                ->addLink('first', $this->urlGenerator->generate($routeName, ['page' => 1, 'size' => $size]))
+                ->addLink('last', $this->urlGenerator->generate($routeName, ['page' => $pageCount, 'size' => $size]))
+            ;
+        }
+
+        if ($page < $pageCount) {
+            $paginatedCollection
+                ->addLink('next', $this->urlGenerator->generate($routeName, ['page' => $page + 1, 'size' => $size]));
+        }
+
+        if ($page > 1) {
+            $paginatedCollection
+                ->addLink('prev', $this->urlGenerator->generate($routeName, ['page' => $page - 1, 'size' => $size]));
+        }
 
-        return new PaginatedCollection($paginator->getIterator(), $total);
+        return $paginatedCollection;
     }
 }

src/Pagination/WorkshopCollectionFactory.php

@@ -6,16 +6,24 @@
 
 use App\Repository\WorkshopRepository;
 use Doctrine\Bundle\DoctrineBundle\Repository\ServiceEntityRepositoryInterface;
+use Symfony\Component\Routing\Generator\UrlGeneratorInterface;
 
 final class WorkshopCollectionFactory extends PaginatedCollectionFactory
 {
     public function __construct(
-        private WorkshopRepository $workshopRepository
+        private WorkshopRepository $workshopRepository,
+        UrlGeneratorInterface $urlGenerator,
     ) {
+        parent::__construct($urlGenerator);
     }
 
     public function getRepository(): ServiceEntityRepositoryInterface
     {
         return $this->workshopRepository;
     }
+
+    public function getRouteName(): string
+    {
+        return 'list_workshop';
+    }
 }

src/Serializer/AttendeeNormalizer.php

@@ -5,14 +5,16 @@
 namespace App\Serializer;
 
 use App\Entity\Attendee;
+use Symfony\Component\Routing\Generator\UrlGeneratorInterface;
 use Symfony\Component\Serializer\Normalizer\AbstractNormalizer;
 use Symfony\Component\Serializer\Normalizer\ContextAwareNormalizerInterface;
 use Symfony\Component\Serializer\Normalizer\ObjectNormalizer;
 
 final class AttendeeNormalizer implements ContextAwareNormalizerInterface
 {
     public function __construct(
-        private ObjectNormalizer $normalizer
+        private ObjectNormalizer $normalizer,
+        private UrlGeneratorInterface $urlGenerator,
     ) {
     }
 
@@ -35,6 +37,16 @@ public function normalize($object, string $format = null, array $context = [])
 
         $context = array_merge($context, $customContext);
 
-        return $this->normalizer->normalize($object, $format, $context);
+        $data = $this->normalizer->normalize($object, $format, $context);
+
+        if (\is_array($data)) {
+            $data['_links']['self']['href'] = $this->urlGenerator->generate('read_attendee', [
+                'identifier' => $object->getIdentifier(),
+            ]);
+
+            $data['_links']['collection']['href'] = $this->urlGenerator->generate('list_attendee');
+        }
+
+        return $data;
     }
 }

src/Serializer/WorkshopNormalizer.php

@@ -5,14 +5,16 @@
 namespace App\Serializer;
 
 use App\Entity\Workshop;
+use Symfony\Component\Routing\Generator\UrlGeneratorInterface;
 use Symfony\Component\Serializer\Normalizer\AbstractNormalizer;
 use Symfony\Component\Serializer\Normalizer\ContextAwareNormalizerInterface;
 use Symfony\Component\Serializer\Normalizer\ObjectNormalizer;
 
 final class WorkshopNormalizer implements ContextAwareNormalizerInterface
 {
     public function __construct(
-        private ObjectNormalizer $normalizer
+        private ObjectNormalizer $normalizer,
+        private UrlGeneratorInterface $urlGenerator,
     ) {
     }
 
@@ -35,6 +37,16 @@ public function normalize($object, string $format = null, array $context = [])
 
         $context = array_merge($context, $customContext);
 
-        return $this->normalizer->normalize($object, $format, $context);
+        $data = $this->normalizer->normalize($object, $format, $context);
+
+        if (\is_array($data)) {
+            $data['_links']['self']['href'] = $this->urlGenerator->generate('read_workshop', [
+                'identifier' => $object->getIdentifier(),
+            ]);
+
+            $data['_links']['collection']['href'] = $this->urlGenerator->generate('list_workshop');
+        }
+
+        return $data;
     }
 }

tests/Controller/Attendee/__snapshots__/ListControllerTest__test_it_should_list_all_attendees__1.json

@@ -12,11 +12,32 @@
                     "workshop_date": "2021-12-07",
                     "attendees": [
                         "Jan Sch\u00e4dlich"
-                    ]
+                    ],
+                    "_links": {
+                        "self": {
+                            "href": "\/workshops\/abba667a-96ae-4f75-9b71-97819b682e8d"
+                        },
+                        "collection": {
+                            "href": "\/workshops"
+                        }
+                    }
                 }
-            ]
+            ],
+            "_links": {
+                "self": {
+                    "href": "\/attendees\/803449f4-9a4c-4ecb-8ce4-cebc804fe70a"
+                },
+                "collection": {
+                    "href": "\/attendees"
+                }
+            }
         }
     ],
     "total": 1,
-    "count": 1
+    "count": 1,
+    "_links": {
+        "self": {
+            "href": "\/attendees?page=1&size=10"
+        }
+    }
 }

tests/Controller/Attendee/__snapshots__/ListControllerTest__test_it_should_paginate_attendees with data set show 1st page, 3 items each__1.json

@@ -5,23 +5,61 @@
             "firstname": "a",
             "lastname": "1",
             "email": "a1@test.de",
-            "workshops": []
+            "workshops": [],
+            "_links": {
+                "self": {
+                    "href": "\/attendees\/4878f198-36ab-4fe3-8189-19662a9764fa"
+                },
+                "collection": {
+                    "href": "\/attendees"
+                }
+            }
         },
         {
             "identifier": "e942ce16-27c2-494f-9d93-03412da980c5",
             "firstname": "b",
             "lastname": "2",
             "email": "b2@test.de",
-            "workshops": []
+            "workshops": [],
+            "_links": {
+                "self": {
+                    "href": "\/attendees\/e942ce16-27c2-494f-9d93-03412da980c5"
+                },
+                "collection": {
+                    "href": "\/attendees"
+                }
+            }
         },
         {
             "identifier": "4714fb8a-83d8-49af-abbf-7c68fc6c9656",
             "firstname": "c",
             "lastname": "3",
             "email": "c3@test.de",
-            "workshops": []
+            "workshops": [],
+            "_links": {
+                "self": {
+                    "href": "\/attendees\/4714fb8a-83d8-49af-abbf-7c68fc6c9656"
+                },
+                "collection": {
+                    "href": "\/attendees"
+                }
+            }
         }
     ],
     "total": 5,
-    "count": 3
+    "count": 3,
+    "_links": {
+        "self": {
+            "href": "\/attendees?page=1&size=3"
+        },
+        "first": {
+            "href": "\/attendees?page=1&size=3"
+        },
+        "last": {
+            "href": "\/attendees?page=2&size=3"
+        },
+        "next": {
+            "href": "\/attendees?page=2&size=3"
+        }
+    }
 }