Paginate tag posts

assets/css/app.less

@@ -180,6 +180,11 @@ form {
   a.button { text-decoration: underline; }
 }
 
+nav.pagination {
+  text-align: center;
+  margin: 1em 0;
+}
+
 @import "flash";
 @import "post";
 @import "security";

public/build/entrypoints.json

@@ -8,7 +8,7 @@
       ],
       "css": [
         "/build/1.10bbd395.css",
-        "/build/app.68d557f9.css"
+        "/build/app.48bfff7a.css"
       ]
     },
     "map": {

public/build/manifest.json

@@ -3,7 +3,7 @@
   "build/0.b868e304.js": "/build/0.b868e304.js",
   "build/1.10bbd395.css": "/build/1.10bbd395.css",
   "build/1.d9793a66.js": "/build/1.d9793a66.js",
-  "build/app.css": "/build/app.68d557f9.css",
+  "build/app.css": "/build/app.48bfff7a.css",
   "build/app.js": "/build/app.2d2d6330.js",
   "build/map.css": "/build/map.f3a81ea1.css",
   "build/map.js": "/build/map.09d99380.js",

src/Controller/TagController.php

@@ -2,6 +2,7 @@
 
 namespace App\Controller;
 
+use App\Repository\PostRepository;
 use App\Repository\TagRepository;
 use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
 use Symfony\Component\HttpFoundation\Request;
@@ -14,7 +15,7 @@ class TagController extends AbstractController
     /**
      * @Route("/tags/{ids}", name="tags")
      */
-    public function tags(TagRepository $tagRepository, $ids = '')
+    public function tags(TagRepository $tagRepository, string $ids = '')
     {
         return $this->render('tag/index.html.twig', [
             'tags' => $tagRepository->findAllOrderedByCount($this->getUser()),
@@ -23,15 +24,37 @@ public function tags(TagRepository $tagRepository, $ids = '')
 
     /**
      * @Route("/T{id}", name="tag_view", requirements={"id"="\d+"})
+     * @Route("/T{id}/page-{pageNum}", name="tag_view_page", requirements={"id"="\d+", "pageNum"="\d+"})
      */
-    public function viewTag(TagRepository $tagRepository, $id): Response
-    {
+    public function viewTag(
+        Request $request,
+        TagRepository $tagRepository,
+        int $id,
+        int $pageNum = 1
+    ): Response {
         $tag = $tagRepository->find($id);
         if (!$tag) {
             throw $this->createNotFoundException();
         }
+        $postCount = $tagRepository->countPosts($tag, $this->getUser());
+        $pageCount = ceil($postCount / 10);
+        if ($pageNum > $pageCount) {
+            // Redirect to last page.
+            return $this->redirectToRoute('tag_view_page', ['id' => $tag->getId(), 'pageNum' => $pageCount]);
+        }
+        if (
+            $pageNum === 1 && $request->get('_route') === 'tag_view_page'
+            || $pageNum < 1
+        ) {
+            // Ensure only one form of URL for page 1, and avoid page 0.
+            return $this->redirectToRoute('tag_view', ['id' => $tag->getId()]);
+        }
         return $this->render('tag/view.html.twig', [
             'tag' => $tag,
+            'posts' => $tagRepository->findPosts($tag, $this->getUser(), $pageNum),
+            'post_count' => $postCount,
+            'page_count' => $pageCount,
+            'page_num' => $pageNum,
         ]);
     }
 

src/Repository/TagRepository.php

@@ -9,7 +9,11 @@
 use Doctrine\Bundle\DoctrineBundle\Repository\ServiceEntityRepository;
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\Common\Collections\Collection;
+use Doctrine\ORM\AbstractQuery;
+use Doctrine\ORM\Query\Expr\Join;
+use Doctrine\ORM\QueryBuilder;
 use Doctrine\Persistence\ManagerRegistry;
+use Exception;
 
 /**
  * @method Tag|null find($id, $lockMode = null, $lockVersion = null)
@@ -36,6 +40,49 @@ public function getFromIdsString(string $ids): array
         ];
     }
 
+    public function countPosts(Tag $tag, ?User $user = null): int
+    {
+        return $this->getPostsQueryBuilder($tag, $user)
+            ->select('COUNT(p)')
+            ->getQuery()
+            ->getResult(AbstractQuery::HYDRATE_SINGLE_SCALAR);
+    }
+
+    /**
+     * @param Tag $tag
+     * @param User|null $user
+     * @param int|null $pageNum
+     * @return array<Post>
+     */
+    public function findPosts(Tag $tag, ?User $user = null, ?int $pageNum = 1): array
+    {
+        $pageSize = 10;
+        return $this->getPostsQueryBuilder($tag, $user)
+            ->setMaxResults($pageSize)
+            ->setFirstResult(($pageNum - 1) * $pageSize)
+            ->getQuery()
+            ->getResult();
+    }
+
+    private function getPostsQueryBuilder(Tag $tag, ?User $user = null): QueryBuilder
+    {
+        if (!$tag->getId()) {
+            throw new Exception('Tag not loaded.');
+        }
+        $groupList = $user ? $user->getGroupIdList() : false;
+        if (!$groupList) {
+            $groupList = UserGroup::PUBLIC;
+        }
+        return $this->getEntityManager()
+            ->createQueryBuilder()
+            ->select('p')
+            ->from(Post::class, 'p')
+            ->join('p.tags', 't', Join::WITH, 't.id = :tag_id')
+            ->setParameter('tag_id', $tag->getId())
+            ->andWhere('p.view_group IN (' . $groupList . ')')
+            ->orderBy('p.date', 'DESC');
+    }
+
     public function findAllOrderedByCount(?User $user)
     {
         $groupList = $user ? $user->getGroupIdList() : UserGroup::PUBLIC;

templates/tag/view.html.twig

@@ -8,6 +8,22 @@
 
     {{ tag.description|markdownToHtml }}
 
-    {% include 'post/_post_list.html.twig' with {posts: tag.posts} %}
+    <nav class="pagination">
+        {% if page_num == 2 %}
+            <a href="{{ path('tag_view', {id: tag.id}) }}">&larr; Prev</a>
+        {% elseif page_num > 1 %}
+            <a href="{{ path('tag_view_page', {id: tag.id, pageNum: page_num - 1}) }}">&larr; Prev</a>
+        {% else %}
+            <span>&larr; Prev</span>
+        {% endif %}
+        | Page {{ page_num }} of {{ page_count }} ({{ post_count }} posts) |
+        {% if page_num < page_count %}
+            <a href="{{ path('tag_view_page', {id: tag.id, pageNum: page_num + 1}) }}">Next &rarr;</a>
+        {% else %}
+            <span>Next &rarr;</span>
+        {% endif %}
+    </nav>
+
+    {% include 'post/_post_list.html.twig' with {posts: posts} %}
 
 {% endblock %}

tests/Repository/RepositoryTestBase.php

@@ -0,0 +1,39 @@
+<?php
+
+namespace App\Tests\Repository;
+
+use App\Entity\Post;
+use App\Kernel;
+use App\Repository\PostRepository;
+use App\Repository\TagRepository;
+use Symfony\Bridge\PhpUnit\ClockMock;
+use Symfony\Bundle\FrameworkBundle\Test\KernelTestCase;
+
+abstract class RepositoryTestBase extends KernelTestCase
+{
+
+    /**
+     * @var \Doctrine\ORM\EntityManager
+     */
+    protected $entityManager;
+
+    protected static function getKernelClass()
+    {
+        return Kernel::class;
+    }
+
+    protected function setUp(): void
+    {
+        // Set a fake clock time of 2020-11-15 07:36:41 and register all our classes that use the time() function.
+        ClockMock::withClockMock(1605425801);
+        ClockMock::register(self::class);
+        ClockMock::register(PostRepository::class);
+        ClockMock::register(TagRepository::class);
+        ClockMock::register(Post::class);
+
+        $kernel = self::bootKernel();
+        $this->entityManager = $kernel->getContainer()
+            ->get('doctrine')
+            ->getManager();
+    }
+}

tests/Repository/TagRepositoryTest.php

@@ -0,0 +1,47 @@
+<?php
+
+namespace App\Tests\Repository;
+
+use App\Entity\Post;
+use App\Entity\Tag;
+use App\Entity\User;
+use App\Entity\UserGroup;
+use App\Repository\PostRepository;
+use App\Repository\TagRepository;
+use Symfony\Component\HttpFoundation\Request;
+
+class TagRepositoryTest extends RepositoryTestBase
+{
+
+    public function testGetPostList()
+    {
+        /** @var TagRepository $tagRepo */
+        $tagRepo = $this->entityManager->getRepository(Tag::class);
+        /** @var PostRepository $postRepo */
+        $postRepo = $this->entityManager->getRepository(Post::class);
+
+        $tag = new Tag();
+        $tag->setTitle('Tag 1');
+        $this->entityManager->persist($tag);
+        $privateGroup = new UserGroup();
+        $privateGroup->setName('Private');
+        $this->entityManager->persist($privateGroup);
+        $this->entityManager->flush();
+
+        // Create two posts tagged the same, one of which is private.
+        $publicPost = new Post();
+        $publicPostData = ['tags' => 'Tag 1', 'view_group' => UserGroup::PUBLIC, 'author' => 1];
+        $postRepo->saveFromRequest($publicPost, new Request([], $publicPostData));
+        $privatePost = new Post();
+        $privatePostData = ['tags' => 'Tag 1', 'view_group' => $privateGroup->getId(), 'author' => 1];
+        $postRepo->saveFromRequest($privatePost, new Request([], $privatePostData));
+
+        // Make sure the user is only in the public group.
+        $user = new User();
+
+        // Check that only one post is returned.
+        $this->assertSame(1, $tagRepo->countPosts($tag, $user));
+        $posts = $tagRepo->findPosts($tag, $user);
+        $this->assertGreaterThan(0, $posts[0]->getId());
+    }
+}