Issue #3013029 by amateescu, dolu: StringFormatter should check whether an...

Issue #3013029 by amateescu, dolu: StringFormatter should check whether an entity type has a 'revision' link template

(cherry picked from commit 58cffff6)

core/lib/Drupal/Core/Field/Plugin/Field/FieldFormatter/StringFormatter.php

@@ -124,7 +124,6 @@ public function viewElements(FieldItemListInterface $items, $langcode) {
     $elements = [];
     $url = NULL;
     if ($this->getSetting('link_to_entity')) {
-      // For the default revision this falls back to 'canonical'.
       $url = $this->getEntityUrl($items->getEntity());
     }
 
@@ -173,8 +172,11 @@ protected function viewValue(FieldItemInterface $item) {
    *   The URI elements of the entity.
    */
   protected function getEntityUrl(EntityInterface $entity) {
-    // For the default revision this falls back to 'canonical'.
-    return $entity->toUrl('revision');
+    // For the default revision, the 'revision' link template falls back to
+    // 'canonical'.
+    // @see \Drupal\Core\Entity\Entity::toUrl()
+    $rel = $entity->getEntityType()->hasLinkTemplate('revision') ? 'revision' : 'canonical';
+    return $entity->toUrl($rel);
   }
 
 }

core/modules/field/tests/src/Kernel/String/StringFormatterTest.php

@@ -24,6 +24,13 @@ class StringFormatterTest extends KernelTestBase {
    */
   public static $modules = ['field', 'text', 'entity_test', 'system', 'filter', 'user'];
 
+  /**
+   * The entity type manager.
+   *
+   * @var \Drupal\Core\Entity\EntityTypeManagerInterface
+   */
+  protected $entityTypeManager;
+
   /**
    * @var string
    */
@@ -79,6 +86,8 @@ protected function setUp() {
         'settings' => [],
       ]);
     $this->display->save();
+
+    $this->entityTypeManager = \Drupal::entityTypeManager();
   }
 
   /**
@@ -145,7 +154,7 @@ public function testStringFormatter() {
     $value2 = $this->randomMachineName();
     $entity->{$this->fieldName}->value = $value2;
     $entity->save();
-    $entity_new_revision = \Drupal::entityManager()->getStorage('entity_test_rev')->loadRevision($old_revision_id);
+    $entity_new_revision = $this->entityTypeManager->getStorage('entity_test_rev')->loadRevision($old_revision_id);
 
     $this->renderEntityFields($entity, $this->display);
     $this->assertLink($value2, 0);
@@ -154,6 +163,19 @@ public function testStringFormatter() {
     $this->renderEntityFields($entity_new_revision, $this->display);
     $this->assertLink($value, 0);
     $this->assertLinkByHref('/entity_test_rev/' . $entity_new_revision->id() . '/revision/' . $entity_new_revision->getRevisionId() . '/view');
+
+    // Check that linking to a revisionable entity works if the entity type does
+    // not specify a 'revision' link template.
+    $entity_type = clone $this->entityTypeManager->getDefinition('entity_test_rev');
+    $link_templates = $entity_type->getLinkTemplates();
+    unset($link_templates['revision']);
+    $entity_type->set('links', $link_templates);
+    \Drupal::state()->set('entity_test_rev.entity_type', $entity_type);
+    $this->entityTypeManager->clearCachedDefinitions();
+
+    $this->renderEntityFields($entity_new_revision, $this->display);
+    $this->assertLink($value, 0);
+    $this->assertLinkByHref($entity->url('canonical'));
   }
 
 }