Issue #3439465 by mglaman, amangrover90, e0ipso, bbrala: List field enhancer...

Issue #3439465 by mglaman, amangrover90, e0ipso, bbrala: List field enhancer for displaying key and value

src/Plugin/jsonapi/FieldEnhancer/ListFieldEnhancer.php

+<?php
+
+namespace Drupal\jsonapi_extras\Plugin\jsonapi\FieldEnhancer;
+
+use Drupal\jsonapi_extras\Plugin\ResourceFieldEnhancerBase;
+use Drupal\options\Plugin\Field\FieldType\ListItemBase;
+use Shaper\Util\Context;
+
+/**
+ * Perform additional manipulations to list fields.
+ *
+ * @ResourceFieldEnhancer(
+ *   id = "list",
+ *   label = @Translation("List Field"),
+ *   description = @Translation("Formats a list field based on labels and values.")
+ * )
+ */
+class ListFieldEnhancer extends ResourceFieldEnhancerBase {
+
+  /**
+   * {@inheritDoc}
+   */
+  protected function doTransform($data, Context $context) {
+    return is_array($data) ? array_column($data, 'value') : $data;
+  }
+
+  /**
+   * {@inheritDoc}
+   */
+  protected function doUndoTransform($data, Context $context) {
+    $field_context = $context->offsetGet('field_item_object');
+    assert($field_context instanceof ListItemBase);
+    $options = $field_context->getPossibleOptions();
+    $reformat = static function ($input) use ($options) {
+      return [
+        'value' => $input,
+        'label' => $options[(string) $input] ?? '',
+      ];
+    };
+    return is_array($data) ? array_map($reformat, $data) : $reformat($data);
+  }
+
+  /**
+   * {@inheritDoc}
+   */
+  public function getOutputJsonSchema(): array {
+    return [
+      'type' => 'array',
+      'items' => [
+        'type' => 'object',
+        'properties' => [
+          'value' => [
+            'anyOf' => [
+              ['type' => 'string'],
+              ['type' => 'number'],
+              ['type' => 'null'],
+            ],
+          ],
+          'label' => [
+            'anOf' => [
+              ['type' => 'string'],
+              ['type' => 'null'],
+            ],
+          ],
+        ],
+      ],
+    ];
+  }
+
+}

tests/src/Kernel/Plugin/jsonapi/FieldEnhancer/ListFieldEnhancerTest.php

+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\jsonapi_extras\Kernel\Plugin\jsonapi\FieldEnhancer;
+
+use Drupal\jsonapi_extras\Plugin\jsonapi\FieldEnhancer\ListFieldEnhancer;
+use Drupal\KernelTests\KernelTestBase;
+use Drupal\options\Plugin\Field\FieldType\ListIntegerItem;
+use Shaper\Util\Context;
+
+/**
+ * Tests ListFieldEnhancer.
+ *
+ * @group jsonapi_extras
+ */
+final class ListFieldEnhancerTest extends KernelTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = [
+    'file',
+    'jsonapi_extras',
+    'jsonapi',
+    'serialization',
+    'system',
+    'user',
+    'options',
+  ];
+
+  /**
+   * Tests JSON schema output.
+   */
+  public function testGetOutputJsonSchema(): void {
+    self::assertEquals([
+      'type' => 'array',
+      'items' => [
+        'type' => 'object',
+        'properties' => [
+          'value' => [
+            'anyOf' => [
+              ['type' => 'string'],
+              ['type' => 'number'],
+              ['type' => 'null'],
+            ],
+          ],
+          'label' => [
+            'anOf' => [
+              ['type' => 'string'],
+              ['type' => 'null'],
+            ],
+          ],
+        ],
+      ],
+    ], $this->getInstance()->getOutputJsonSchema());
+  }
+
+  /**
+   * Tests transform.
+   */
+  public function testTransform(): void {
+    $output = $this->getInstance()->transform([['value' => 1]]);
+    self::assertEquals([1], $output);
+    $output = $this->getInstance()->transform('foo');
+    self::assertEquals('foo', $output);
+  }
+
+  /**
+   * Tests undo transform.
+   */
+  public function testUndoTransform(): void {
+    $field_item = $this->createMock(ListIntegerItem::class);
+    $field_item->expects($this->once())
+      ->method('getPossibleOptions')
+      ->willReturn([1 => 'One', 2 => 'Two', 3 => 'Three']);
+    $context = new Context();
+    $context['field_item_object'] = $field_item;
+    $output = $this->getInstance()->undoTransform([3, 1, 2], $context);
+    self::assertEquals(
+      [
+        ['value' => 3, 'label' => 'Three'],
+        ['value' => 1, 'label' => 'One'],
+        ['value' => 2, 'label' => 'Two'],
+      ],
+      $output
+    );
+  }
+
+  /**
+   * Gets a plugin instance for testing.
+   *
+   * @return \Drupal\jsonapi_extras\Plugin\jsonapi\FieldEnhancer\ListFieldEnhancer
+   *   The plugin instance.
+   */
+  private function getInstance(): ListFieldEnhancer {
+    return $this->container->get('plugin.manager.resource_field_enhancer')->createInstance('list');
+  }
+
+}