Issue #2821352 by chr.fritsch, jian he, Pancho, RaphaelBriskie, jonathanshaw, alexpott, amateescu, larowlan: EntityReferenceAutocompleteWidget::getAutocreateBundle() unnecessarily requires the 'target_bundles' setting

core/lib/Drupal/Core/Entity/Plugin/EntityReferenceSelection/DefaultSelection.php

@@ -373,13 +373,16 @@ class DefaultSelection extends SelectionPluginBase implements ContainerFactoryPl
    */
   public function createNewEntity($entity_type_id, $bundle, $label, $uid) {
     $entity_type = $this->entityTypeManager->getDefinition($entity_type_id);
-    $bundle_key = $entity_type->getKey('bundle');
-    $label_key = $entity_type->getKey('label');
 
-    $entity = $this->entityTypeManager->getStorage($entity_type_id)->create([
-      $bundle_key => $bundle,
-      $label_key => $label,
-    ]);
+    $values = [
+      $entity_type->getKey('label') => $label,
+    ];
+
+    if ($bundle_key = $entity_type->getKey('bundle')) {
+      $values[$bundle_key] = $bundle;
+    }
+
+    $entity = $this->entityTypeManager->getStorage($entity_type_id)->create($values);
 
     if ($entity instanceof EntityOwnerInterface) {
       $entity->setOwnerId($uid);

core/lib/Drupal/Core/Field/Plugin/Field/FieldWidget/EntityReferenceAutocompleteWidget.php

@@ -117,7 +117,7 @@ class EntityReferenceAutocompleteWidget extends WidgetBase {
       '#placeholder' => $this->getSetting('placeholder'),
     ];
 
-    if ($this->getSelectionHandlerSetting('auto_create') && ($bundle = $this->getAutocreateBundle())) {
+    if ($bundle = $this->getAutocreateBundle()) {
       $element['#autocreate'] = [
         'bundle' => $bundle,
         'uid' => ($entity instanceof EntityOwnerInterface) ? $entity->getOwnerId() : \Drupal::currentUser()->id(),
@@ -154,16 +154,23 @@ class EntityReferenceAutocompleteWidget extends WidgetBase {
    * Returns the name of the bundle which will be used for autocreated entities.
    *
    * @return string
-   *   The bundle name.
+   *   The bundle name. If autocreate is not active, NULL will be returned.
    */
   protected function getAutocreateBundle() {
     $bundle = NULL;
-    if ($this->getSelectionHandlerSetting('auto_create') && $target_bundles = $this->getSelectionHandlerSetting('target_bundles')) {
+    if ($this->getSelectionHandlerSetting('auto_create')) {
+      $target_bundles = $this->getSelectionHandlerSetting('target_bundles');
+      // If there's no target bundle at all, use the target_type. It's the
+      // default for bundleless entity types.
+      if (empty($target_bundles)) {
+        $bundle = $this->getFieldSetting('target_type');
+      }
       // If there's only one target bundle, use it.
-      if (count($target_bundles) == 1) {
+      elseif (count($target_bundles) == 1) {
         $bundle = reset($target_bundles);
       }
-      // Otherwise use the target bundle stored in selection handler settings.
+      // If there's more than one target bundle, use the autocreate bundle
+      // stored in selection handler settings.
       elseif (!$bundle = $this->getSelectionHandlerSetting('auto_create_bundle')) {
         // If no bundle has been set as auto create target means that there is
         // an inconsistency in entity reference field settings.

core/modules/field/tests/src/Functional/EntityReference/EntityReferenceAutoCreateTest.php

@@ -19,7 +19,7 @@ class EntityReferenceAutoCreateTest extends BrowserTestBase {
 
   use EntityReferenceTestTrait;
 
-  protected static $modules = ['node', 'taxonomy'];
+  protected static $modules = ['node', 'taxonomy', 'entity_test'];
 
   /**
    * {@inheritdoc}
@@ -237,4 +237,51 @@ class EntityReferenceAutoCreateTest extends BrowserTestBase {
     // $this->assertErrorLogged($error_message);
   }
 
+  /**
+   * Tests autocreation for an entity that has no bundles.
+   */
+  public function testNoBundles() {
+    $account = $this->drupalCreateUser([
+      'access content',
+      "create $this->referencingType content",
+      'administer entity_test content',
+    ]);
+    $this->drupalLogin($account);
+
+    $field_name = mb_strtolower($this->randomMachineName());
+    $handler_settings = [
+      'auto_create' => TRUE,
+    ];
+    $this->createEntityReferenceField('node', $this->referencingType, $field_name, $this->randomString(), 'entity_test_no_bundle_with_label', 'default', $handler_settings);
+    \Drupal::service('entity_display.repository')
+      ->getFormDisplay('node', $this->referencingType)
+      ->setComponent($field_name, ['type' => 'entity_reference_autocomplete'])
+      ->save();
+
+    $node_title = $this->randomMachineName();
+    $name = $this->randomMachineName();
+    $edit = [
+      $field_name . '[0][target_id]' => $name,
+      'title[0][value]' => $node_title,
+    ];
+
+    $this->drupalPostForm('node/add/' . $this->referencingType, $edit, 'Save');
+
+    // Assert referenced entity was created.
+    $result = \Drupal::entityQuery('entity_test_no_bundle_with_label')
+      ->condition('name', $name)
+      ->execute();
+    $this->assertNotEmpty($result, 'Referenced entity was created.');
+    $referenced_id = key($result);
+
+    // Assert the referenced entity is associated with referencing node.
+    $result = \Drupal::entityQuery('node')
+      ->condition('type', $this->referencingType)
+      ->execute();
+    $this->assertCount(1, $result);
+    $referencing_nid = key($result);
+    $referencing_node = Node::load($referencing_nid);
+    $this->assertEqual($referenced_id, $referencing_node->$field_name->target_id, 'Newly created node is referenced from the referencing entity.');
+  }
+
 }

core/modules/system/tests/modules/entity_test/src/Entity/EntityTestNoBundleWithLabel.php

@@ -0,0 +1,28 @@
+<?php
+
+namespace Drupal\entity_test\Entity;
+
+/**
+ * Test entity class with no bundle but with label.
+ *
+ * @ContentEntityType(
+ *   id = "entity_test_no_bundle_with_label",
+ *   label = @Translation("Entity Test without bundle but with label"),
+ *   base_table = "entity_test_no_bundle_with_label",
+ *   handlers = {
+ *     "views_data" = "Drupal\views\EntityViewsData"
+ *   },
+ *   entity_keys = {
+ *     "id" = "id",
+ *     "label" = "name",
+ *     "revision" = "revision_id",
+ *   },
+ *   admin_permission = "administer entity_test content",
+ *   links = {
+ *     "add-form" = "/entity_test_no_bundle_with_label/add",
+ *   },
+ * )
+ */
+class EntityTestNoBundleWithLabel extends EntityTest {
+
+}