Issue #2804391 by Berdir, Jo Fitzgerald, amateescu, gaurav.kapoor, arunkumark, wolffereast: Resaving menu links that points to a non-node entity changes the type to node and breaks the link

core/modules/link/src/Plugin/Field/FieldWidget/LinkWidget.php

@@ -72,8 +72,9 @@ class LinkWidget extends WidgetBase {
     elseif ($scheme === 'entity') {
       list($entity_type, $entity_id) = explode('/', substr($uri, 7), 2);
       // Show the 'entity:' URI as the entity autocomplete would.
-      $entity_manager = \Drupal::entityManager();
-      if ($entity_manager->getDefinition($entity_type, FALSE) && $entity = \Drupal::entityManager()->getStorage($entity_type)->load($entity_id)) {
+      // @todo Support entity types other than 'node'. Will be fixed in
+      //    https://www.drupal.org/node/2423093.
+      if ($entity_type == 'node' && $entity = \Drupal::entityTypeManager()->getStorage($entity_type)->load($entity_id)) {
         $displayable_string = EntityAutocomplete::getEntityLabels([$entity]);
       }
     }

core/modules/link/tests/src/Functional/LinkFieldTest.php

@@ -8,6 +8,7 @@ use Drupal\Core\Url;
 use Drupal\entity_test\Entity\EntityTest;
 use Drupal\field\Entity\FieldConfig;
 use Drupal\link\LinkItemInterface;
+use Drupal\node\NodeInterface;
 use Drupal\Tests\BrowserTestBase;
 use Drupal\field\Entity\FieldStorageConfig;
 
@@ -95,11 +96,7 @@ class LinkFieldTest extends BrowserTestBase {
     // Create a node to test the link widget.
     $node = $this->drupalCreateNode();
 
-    // Create an entity with restricted view access.
-    $entity_test_no_label_access = EntityTest::create([
-      'name' => 'forbid_access',
-    ]);
-    $entity_test_no_label_access->save();
+    $restricted_node = $this->drupalCreateNode(['status' => NodeInterface::NOT_PUBLISHED]);
 
     // Define some valid URLs (keys are the entered values, values are the
     // strings displayed to the user).
@@ -134,7 +131,7 @@ class LinkFieldTest extends BrowserTestBase {
       // Entity URI displayed as ER autocomplete value when displayed in a form.
       'entity:node/1' => $node->label() . ' (1)',
       // URI for an entity that exists, but is not accessible by the user.
-      'entity:entity_test/' . $entity_test_no_label_access->id() => '- Restricted access - (' . $entity_test_no_label_access->id() . ')',
+      'entity:node/' . $restricted_node->id() => '- Restricted access - (' . $restricted_node->id() . ')',
       // URI for an entity that doesn't exist, but with a valid ID.
       'entity:user/999999' => 'entity:user/999999',
     ];
@@ -652,6 +649,67 @@ class LinkFieldTest extends BrowserTestBase {
     $this->assertEqual($form[$field_name]['widget'][0]['uri']['#link_type'], $link_type);
   }
 
+
+  /**
+   * Tests editing a link to a non-node entity.
+   */
+  public function testEditNonNodeEntityLink() {
+
+    $entity_type_manager = \Drupal::entityTypeManager();
+    $entity_test_storage = $entity_type_manager->getStorage('entity_test');
+
+    // Create a field with settings to validate.
+    $this->fieldStorage = FieldStorageConfig::create([
+      'field_name' => 'field_link',
+      'entity_type' => 'entity_test',
+      'type' => 'link',
+      'cardinality' => 1,
+    ]);
+    $this->fieldStorage->save();
+    FieldConfig::create([
+      'field_storage' => $this->fieldStorage,
+      'label' => 'Read more about this entity',
+      'bundle' => 'entity_test',
+      'settings' => [
+        'title' => DRUPAL_OPTIONAL,
+      ],
+    ])->save();
+
+    $entity_type_manager
+      ->getStorage('entity_form_display')
+      ->load('entity_test.entity_test.default')
+      ->setComponent('field_link', [
+        'type' => 'link_default',
+      ])
+      ->save();
+
+    // Create a node and a test entity to have a possibly valid reference for
+    // both. Create another test entity that references the first test entity.
+    $entity_test_link = $entity_test_storage->create(['name' => 'correct link target']);
+    $entity_test_link->save();
+
+    $node = $this->drupalCreateNode(['wrong link target']);
+
+    $correct_link = 'entity:entity_test/' . $entity_test_link->id();
+    $entity_test = $entity_test_storage->create([
+      'name' => 'correct link target',
+      'field_link' => $correct_link,
+    ]);
+    $entity_test->save();
+
+    // Edit the entity and save it, verify the correct link is kept and not
+    // changed to point to a node. Currently, widget does not support non-node
+    // autocomplete and therefore must show the link unaltered.
+    $this->drupalGet($entity_test->toUrl('edit-form'));
+    $this->assertSession()->fieldValueEquals('field_link[0][uri]', $correct_link);
+    $this->drupalPostForm(NULL, [], 'Save');
+
+    $entity_test_storage->resetCache();
+    $entity_test = $entity_test_storage->load($entity_test->id());
+
+    $this->assertEquals($correct_link, $entity_test->get('field_link')->uri);
+  }
+
   /**
    * Renders a test_entity and returns the output.
    *