Issue #2935738 by samuel.mortenson, Wim Leers, Berdir: Entity reference field subclasses (such as file and image fields) lose the non-default properties upon denormalization, in both hal_json and json

core/modules/hal/src/Normalizer/EntityReferenceItemNormalizer.php

@@ -149,7 +149,7 @@ class EntityReferenceItemNormalizer extends FieldItemNormalizer implements UuidR
     $target_type = $field_definition->getSetting('target_type');
     $id = $this->entityResolver->resolve($this, $data, $target_type);
     if (isset($id)) {
-      return ['target_id' => $id];
+      return ['target_id' => $id] + array_intersect_key($data, $field_item->getProperties());
     }
     return NULL;
   }

core/modules/rest/tests/src/Functional/FileUploadResourceTestBase.php

@@ -199,10 +199,6 @@ abstract class FileUploadResourceTestBase extends ResourceTestBase {
     $response = $this->request('POST', $entity_test_post_url, $request_options);
     $this->assertResourceResponse(201, FALSE, $response);
     $this->assertTrue($this->fileStorage->loadUnchanged(1)->isPermanent());
-    // @todo Remove this early return in https://www.drupal.org/project/drupal/issues/2935738.
-    if (static::$format === 'hal_json') {
-      return;
-    }
     $this->assertSame([
       [
         'target_id' => '1',

core/modules/serialization/src/Normalizer/EntityReferenceFieldItemNormalizer.php

@@ -78,7 +78,7 @@ class EntityReferenceFieldItemNormalizer extends FieldItemNormalizer {
         throw new UnexpectedValueException(sprintf('The field "%s" property "target_type" must be set to "%s" or omitted.', $field_item->getFieldDefinition()->getName(), $target_type));
       }
       if ($entity = $this->entityRepository->loadEntityByUuid($target_type, $data['target_uuid'])) {
-        return ['target_id' => $entity->id()];
+        return ['target_id' => $entity->id()] + array_intersect_key($data, $field_item->getProperties());
       }
       else {
         // Unable to load entity by uuid.

core/modules/serialization/tests/src/Unit/Normalizer/EntityReferenceFieldItemNormalizerTest.php

@@ -4,12 +4,14 @@ namespace Drupal\Tests\serialization\Unit\Normalizer;
 
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Field\FieldDefinitionInterface;
+use Drupal\Core\TypedData\Type\IntegerInterface;
 use Drupal\Core\TypedData\TypedDataInterface;
 use Drupal\Core\Entity\EntityRepositoryInterface;
 use Drupal\Core\Entity\FieldableEntityInterface;
 use Drupal\Core\Field\FieldItemInterface;
 use Drupal\Core\Field\FieldItemListInterface;
 use Drupal\Core\Field\Plugin\Field\FieldType\EntityReferenceItem;
+use Drupal\locale\StringInterface;
 use Drupal\serialization\Normalizer\EntityReferenceFieldItemNormalizer;
 use Drupal\Tests\UnitTestCase;
 use Prophecy\Argument;
@@ -237,6 +239,9 @@ class EntityReferenceFieldItemNormalizerTest extends UnitTestCase {
       ->willReturn($entity)
       ->shouldBeCalled();
 
+    $this->fieldItem->getProperties()->willReturn([
+      'target_id' => $this->prophesize(IntegerInterface::class),
+    ]);
     $this->fieldItem->setValue(['target_id' => 'test'])->shouldBeCalled();
 
     $this->assertDenormalize($data);
@@ -260,6 +265,9 @@ class EntityReferenceFieldItemNormalizerTest extends UnitTestCase {
       ->willReturn($entity)
       ->shouldBeCalled();
 
+    $this->fieldItem->getProperties()->willReturn([
+      'target_id' => $this->prophesize(IntegerInterface::class),
+    ]);
     $this->fieldItem->setValue(['target_id' => 'test'])->shouldBeCalled();
 
     $this->assertDenormalize($data);
@@ -361,4 +369,36 @@ class EntityReferenceFieldItemNormalizerTest extends UnitTestCase {
     $this->assertSame($context['target_instance'], $denormalized);
   }
 
+  /**
+   * @covers ::constructValue
+   */
+  public function testConstructValueProperties() {
+    $data = [
+      'target_id' => 'test',
+      'target_type' => 'test_type',
+      'target_uuid' => '080e3add-f9d5-41ac-9821-eea55b7b42fb',
+      'extra_property' => 'extra_value',
+    ];
+
+    $entity = $this->prophesize(FieldableEntityInterface::class);
+    $entity->id()
+      ->willReturn('test')
+      ->shouldBeCalled();
+    $this->entityRepository
+      ->loadEntityByUuid($data['target_type'], $data['target_uuid'])
+      ->willReturn($entity)
+      ->shouldBeCalled();
+
+    $this->fieldItem->getProperties()->willReturn([
+      'target_id' => $this->prophesize(IntegerInterface::class),
+      'extra_property' => $this->prophesize(StringInterface::class),
+    ]);
+    $this->fieldItem->setValue([
+      'target_id' => 'test',
+      'extra_property' => 'extra_value',
+    ])->shouldBeCalled();
+
+    $this->assertDenormalize($data);
+  }
+
 }