Issue #2885486 by seanB, timmillwood, tstoeckler, Wim Leers: Media entity is revisionable but doesn't have a revision link template

core/modules/media/media.permissions.yml

@@ -23,3 +23,7 @@ delete any media:
 
 create media:
   title: 'Create media'
+
+view all media revisions:
+  title: 'View all media revisions'
+  description: 'To view a revision, you also need permission to view the media item.'

core/modules/media/media.routing.yml

@@ -4,3 +4,18 @@ entity.media.multiple_delete_confirm:
     _form: '\Drupal\media\Form\MediaDeleteMultipleConfirmForm'
   requirements:
     _permission: 'administer media+delete any media'
+
+entity.media.revision:
+  path: '/media/{media}/revisions/{media_revision}/view'
+  defaults:
+    _controller: '\Drupal\Core\Entity\Controller\EntityViewController::viewRevision'
+    _title_callback: '\Drupal\Core\Entity\Controller\EntityController::title'
+  options:
+    parameters:
+      media:
+        type: entity:media
+      media_revision:
+        type: entity_revision:media
+  requirements:
+    _access_media_revision: 'view'
+    media: \d+

core/modules/media/media.services.yml

@@ -2,3 +2,9 @@ services:
   plugin.manager.media.source:
     class: Drupal\media\MediaSourceManager
     parent: default_plugin_manager
+
+  access_check.media.revision:
+    class: Drupal\media\Access\MediaRevisionAccessCheck
+    arguments: ['@entity_type.manager']
+    tags:
+      - { name: access_check, applies_to: _access_media_revision }

core/modules/media/src/Access/MediaRevisionAccessCheck.php

@@ -0,0 +1,151 @@
+<?php
+
+namespace Drupal\media\Access;
+
+use Drupal\Core\Access\AccessResult;
+use Drupal\Core\Entity\EntityTypeManagerInterface;
+use Drupal\Core\Routing\Access\AccessInterface;
+use Drupal\Core\Session\AccountInterface;
+use Drupal\media\MediaInterface;
+use Symfony\Component\Routing\Route;
+
+/**
+ * Provides an access checker for media item revisions.
+ *
+ * @ingroup media_access
+ */
+class MediaRevisionAccessCheck implements AccessInterface {
+
+  /**
+   * The media storage.
+   *
+   * @var \Drupal\Core\Entity\ContentEntityStorageInterface
+   */
+  protected $mediaStorage;
+
+  /**
+   * The media access control handler.
+   *
+   * @var \Drupal\Core\Entity\EntityAccessControlHandlerInterface
+   */
+  protected $mediaAccess;
+
+  /**
+   * A static cache of access checks.
+   *
+   * @var array
+   */
+  protected $access = [];
+
+  /**
+   * Constructs a new MediaRevisionAccessCheck.
+   *
+   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
+   *   The entity type manager.
+   */
+  public function __construct(EntityTypeManagerInterface $entity_type_manager) {
+    $this->mediaStorage = $entity_type_manager->getStorage('media');
+    $this->mediaAccess = $entity_type_manager->getAccessControlHandler('media');
+  }
+
+  /**
+   * Checks routing access for the media item revision.
+   *
+   * @param \Symfony\Component\Routing\Route $route
+   *   The route to check against.
+   * @param \Drupal\Core\Session\AccountInterface $account
+   *   The currently logged in account.
+   * @param int $media_revision
+   *   (optional) The media item revision ID. If not specified, but $media is,
+   *   access is checked for that object's revision.
+   * @param \Drupal\media\MediaInterface $media
+   *   (optional) A media item. Used for checking access to a media items
+   *   default revision when $media_revision is unspecified. Ignored when
+   *   $media_revision is specified. If neither $media_revision nor $media are
+   *   specified, then access is denied.
+   *
+   * @return \Drupal\Core\Access\AccessResultInterface
+   *   The access result.
+   */
+  public function access(Route $route, AccountInterface $account, $media_revision = NULL, MediaInterface $media = NULL) {
+    if ($media_revision) {
+      $media = $this->mediaStorage->loadRevision($media_revision);
+    }
+    $operation = $route->getRequirement('_access_media_revision');
+    return AccessResult::allowedIf($media && $this->checkAccess($media, $account, $operation))->cachePerPermissions()->addCacheableDependency($media);
+  }
+
+  /**
+   * Checks media item revision access.
+   *
+   * @param \Drupal\media\MediaInterface $media
+   *   The media item to check.
+   * @param \Drupal\Core\Session\AccountInterface $account
+   *   A user object representing the user for whom the operation is to be
+   *   performed.
+   * @param string $op
+   *   (optional) The specific operation being checked. Defaults to 'view'.
+   *
+   * @return bool
+   *   TRUE if the operation may be performed, FALSE otherwise.
+   */
+  public function checkAccess(MediaInterface $media, AccountInterface $account, $op = 'view') {
+    if (!$media || $op !== 'view') {
+      // If there was no media to check against, or the $op was not one of the
+      // supported ones, we return access denied.
+      return FALSE;
+    }
+
+    // Statically cache access by revision ID, language code, user account ID,
+    // and operation.
+    $langcode = $media->language()->getId();
+    $cid = $media->getRevisionId() . ':' . $langcode . ':' . $account->id() . ':' . $op;
+
+    if (!isset($this->access[$cid])) {
+      // Perform basic permission checks first.
+      if (!$account->hasPermission('view all media revisions') && !$account->hasPermission('administer media')) {
+        $this->access[$cid] = FALSE;
+        return FALSE;
+      }
+
+      // There should be at least two revisions. If the revision ID of the
+      // given media item and the revision ID of the default revision differ,
+      // then we already have two different revisions so there is no need for a
+      // separate database check.
+      if ($media->isDefaultRevision() && ($this->countDefaultLanguageRevisions($media) == 1)) {
+        $this->access[$cid] = FALSE;
+      }
+      elseif ($account->hasPermission('administer media')) {
+        $this->access[$cid] = TRUE;
+      }
+      else {
+        // First check the access to the default revision and finally, if the
+        // media passed in is not the default revision then access to that, too.
+        $this->access[$cid] = $this->mediaAccess->access($this->mediaStorage->load($media->id()), $op, $account) && ($media->isDefaultRevision() || $this->mediaAccess->access($media, $op, $account));
+      }
+    }
+
+    return $this->access[$cid];
+  }
+
+  /**
+   * Counts the number of revisions in the default language.
+   *
+   * @param \Drupal\media\MediaInterface $media
+   *   The media item for which to to count the revisions.
+   *
+   * @return int
+   *   The number of revisions in the default language.
+   */
+  protected function countDefaultLanguageRevisions(MediaInterface $media) {
+    $entity_type = $media->getEntityType();
+    $count = $this->mediaStorage->getQuery()
+      ->allRevisions()
+      ->condition($entity_type->getKey('id'), $media->id())
+      ->condition($entity_type->getKey('default_langcode'), 1)
+      ->count()
+      ->execute();
+    return $count;
+  }
+
+}

core/modules/media/src/Entity/Media.php

@@ -76,6 +76,7 @@ use Drupal\user\UserInterface;
  *     "canonical" = "/media/{media}",
  *     "delete-form" = "/media/{media}/delete",
  *     "edit-form" = "/media/{media}/edit",
+ *     "revision" = "/media/{media}/revisions/{media_revision}/view",
  *     "admin-form" = "/admin/structure/media/manage/{media_type}"
  *   }
  * )

core/modules/media/tests/src/Functional/MediaRevisionTest.php

@@ -4,6 +4,9 @@ namespace Drupal\Tests\media\Functional;
 
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\field\Entity\FieldConfig;
+use Drupal\media\MediaInterface;
+use Drupal\user\Entity\Role;
+use Drupal\user\RoleInterface;
 
 /**
  * Tests the revisionability of media entities.
@@ -12,6 +15,62 @@ use Drupal\field\Entity\FieldConfig;
  */
 class MediaRevisionTest extends MediaFunctionalTestBase {
 
+  /**
+   * Checks media revision operations.
+   */
+  public function testRevisions() {
+    $assert = $this->assertSession();
+
+    /** @var \Drupal\Core\Entity\Sql\SqlContentEntityStorage $media_storage */
+    $media_storage = $this->container->get('entity.manager')->getStorage('media');
+
+    // Create a media type and media item.
+    $media_type = $this->createMediaType();
+    $media = $media_storage->create([
+      'bundle' => $media_type->id(),
+      'name' => 'Unnamed',
+    ]);
+    $media->save();
+
+    // You can't access the revision page when there is only 1 revision.
+    $this->drupalGet('media/' . $media->id() . '/revisions/' . $media->getRevisionId() . '/view');
+    $assert->statusCodeEquals(403);
+
+    // Create some revisions.
+    $media_revisions = [];
+    $media_revisions[] = clone $media;
+    $revision_count = 3;
+    for ($i = 0; $i < $revision_count; $i++) {
+      $media->revision_log = $this->randomMachineName(32);
+      $media = $this->createMediaRevision($media);
+      $media_revisions[] = clone $media;
+    }
+
+    // Get the last revision for simple checks.
+    /** @var \Drupal\media\MediaInterface $media */
+    $media = end($media_revisions);
+
+    // Test permissions.
+    $this->drupalLogin($this->nonAdminUser);
+    /** @var \Drupal\user\RoleInterface $role */
+    $role = Role::load(RoleInterface::AUTHENTICATED_ID);
+
+    // Test 'view all media revisions' permission ('view media' permission is
+    // needed as well).
+    user_role_revoke_permissions($role->id(), ['view media', 'view all media revisions']);
+    $this->drupalGet('media/' . $media->id() . '/revisions/' . $media->getRevisionId() . '/view');
+    $assert->statusCodeEquals(403);
+    $this->grantPermissions($role, ['view media', 'view all media revisions']);
+    $this->drupalGet('media/' . $media->id() . '/revisions/' . $media->getRevisionId() . '/view');
+    $assert->statusCodeEquals(200);
+
+    // Confirm the revision page shows the correct title.
+    $assert->pageTextContains($media->label());
+
+    // Confirm that the last revision is the default revision.
+    $this->assertTrue($media->isDefaultRevision(), 'Last revision is the default.');
+  }
+
   /**
    * Tests creating revisions of a File media item.
    */
@@ -43,6 +102,13 @@ class MediaRevisionTest extends MediaFunctionalTestBase {
     $page->fillField('Name', 'Foobaz');
     $page->pressButton('Save and keep published');
     $this->assertRevisionCount($media, 2);
+
+    // Confirm the correct revision title appears on "view revisions" page.
+    $media = $this->container->get('entity_type.manager')
+      ->getStorage('media')
+      ->loadUnchanged(1);
+    $this->drupalGet("media/" . $media->id() . "/revisions/" . $media->getRevisionId() . "/view");
+    $assert->pageTextContains('Foobaz');
   }
 
   /**
@@ -83,6 +149,29 @@ class MediaRevisionTest extends MediaFunctionalTestBase {
     $page->fillField('Name', 'Foobaz');
     $page->pressButton('Save and keep published');
     $this->assertRevisionCount($media, 2);
+
+    // Confirm the correct revision title appears on "view revisions" page.
+    $media = $this->container->get('entity_type.manager')
+      ->getStorage('media')
+      ->loadUnchanged(1);
+    $this->drupalGet("media/" . $media->id() . "/revisions/" . $media->getRevisionId() . "/view");
+    $assert->pageTextContains('Foobaz');
+  }
+
+  /**
+   * Creates a new revision for a given media item.
+   *
+   * @param \Drupal\media\MediaInterface $media
+   *   A media object.
+   *
+   * @return \Drupal\media\MediaInterface
+   *   A media object with up to date revision information.
+   */
+  protected function createMediaRevision(MediaInterface $media) {
+    $media->set('name', $this->randomMachineName());
+    $media->setNewRevision();
+    $media->save();
+    return $media;
   }
 
   /**