Issue #2767125 by hchonov, amateescu: EntityFormDisplay::validateFormValues sets form state errors by empty name string instead using the provided form element

core/lib/Drupal/Core/Entity/Entity/EntityFormDisplay.php

@@ -236,7 +236,7 @@ class EntityFormDisplay extends EntityDisplayBase implements EntityFormDisplayIn
     // Flag entity level violations.
     foreach ($violations->getEntityViolations() as $violation) {
       /** @var \Symfony\Component\Validator\ConstraintViolationInterface $violation */
-      $form_state->setErrorByName('', $violation->getMessage());
+      $form_state->setError($form, $violation->getMessage());
     }
 
     $this->flagWidgetsErrorsFromViolations($violations, $form, $form_state);

core/modules/field/src/Tests/NestedFormTest.php

@@ -165,4 +165,30 @@ class NestedFormTest extends FieldTestBase {
     $this->assertFieldValues($entity_2, 'field_unlimited', array(13, 14, 15));
   }
 
+  /**
+   * Tests entity level validation within subforms.
+   */
+  public function testNestedEntityFormEntityLevelValidation() {
+    // Create two entities.
+    $storage = $this->container->get('entity_type.manager')
+      ->getStorage('entity_test_constraints');
+
+    $entity_1 = $storage->create();
+    $entity_1->save();
+
+    $entity_2 = $storage->create();
+    $entity_2->save();
+
+    // Display the 'combined form'.
+    $this->drupalGet("test-entity-constraints/nested/{$entity_1->id()}/{$entity_2->id()}");
+    $this->assertFieldByName('entity_2[changed]', 0, 'Entity 2: changed value appears correctly in the form.');
+
+    // Submit the form and check that the entities are updated accordingly.
+    $edit = ['entity_2[changed]' => REQUEST_TIME - 86400];
+    $this->drupalPostForm(NULL, $edit, t('Save'));
+
+    $elements = $this->cssSelect('.entity-2.error');
+    $this->assertEqual(1, count($elements), 'The whole nested entity form has been correctly flagged with an error class.');
+  }
+
 }

core/modules/field/tests/modules/field_test/field_test.routing.yml

@@ -11,3 +11,17 @@ field_test.entity_nested_form:
         type: 'entity:entity_test'
   requirements:
     _permission: 'administer entity_test content'
+
+field_test.entity_constraints_nested_form:
+  path: '/test-entity-constraints/nested/{entity_1}/{entity_2}'
+  defaults:
+    _title: 'Nested entity form'
+    _form: '\Drupal\field_test\Form\NestedEntityTestForm'
+  options:
+    parameters:
+      entity_1:
+        type: 'entity:entity_test_constraints'
+      entity_2:
+        type: 'entity:entity_test_constraints'
+  requirements:
+    _permission: 'administer entity_test content'

core/modules/field/tests/modules/field_test/src/Form/NestedEntityTestForm.php

@@ -2,6 +2,7 @@
 
 namespace Drupal\field_test\Form;
 
+use Drupal\Core\Entity\EntityChangedInterface;
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Form\FormBase;
 use Drupal\Core\Form\FormStateInterface;
@@ -33,16 +34,26 @@ class NestedEntityTestForm extends FormBase {
     $form_state->set('entity_2', $entity_2);
     $form_display_2 = EntityFormDisplay::collectRenderDisplay($entity_2, 'default');
     $form_state->set('form_display_2', $form_display_2);
-    $form['entity_2'] = array(
+    $form['entity_2'] = [
       '#type' => 'details',
       '#title' => t('Second entity'),
       '#tree' => TRUE,
-      '#parents' => array('entity_2'),
+      '#parents' => ['entity_2'],
       '#weight' => 50,
-    );
+      '#attributes' => ['class' => ['entity-2']]
+    ];
 
     $form_display_2->buildForm($entity_2, $form['entity_2'], $form_state);
 
+    if ($entity_2 instanceof EntityChangedInterface) {
+      // Changed must be sent to the client, for later overwrite error checking.
+      // @see Drupal\field\Tests\NestedFormTest::testNestedEntityFormEntityLevelValidation()
+      $form['entity_2']['changed'] = [
+        '#type' => 'hidden',
+        '#default_value' => $entity_1->getChangedTime(),
+      ];
+    }
+
     $form['save'] = array(
       '#type' => 'submit',
       '#value' => t('Save'),
@@ -65,7 +76,16 @@ class NestedEntityTestForm extends FormBase {
     $entity_2 = $form_state->get('entity_2');
     /** @var \Drupal\Core\Entity\Display\EntityFormDisplayInterface $form_display_2 */
     $form_display_2 = $form_state->get('form_display_2');
-    $form_display_2->extractFormValues($entity_2, $form['entity_2'], $form_state);
+    $extracted = $form_display_2->extractFormValues($entity_2, $form['entity_2'], $form_state);
+    // Extract the values of fields that are not rendered through widgets, by
+    // simply copying from top-level form values. This leaves the fields that
+    // are not being edited within this form untouched.
+    // @see Drupal\field\Tests\NestedFormTest::testNestedEntityFormEntityLevelValidation()
+    foreach ($form_state->getValues()['entity_2'] as $name => $values) {
+      if ($entity_2->hasField($name) && !isset($extracted[$name])) {
+        $entity_2->set($name, $values);
+      }
+    }
     $form_display_2->validateFormValues($entity_2, $form['entity_2'], $form_state);
   }