Issue #3145076 by johnwebdev, alexpott, Sam152: [backport] MapItem base fields...

      // A dedicated table only contain rows for actual field values, and no

      // rows for entities where the field is empty. Thus, we can safely

      // enforce 'not null' on the columns for the field's required properties.

      // Fields can have dynamic properties, so we need to make sure that the

      // property is statically defined.

      if (isset($properties[$column_name])) {

        $data_schema['fields'][$real_name]['not null'] = $properties[$column_name]->isRequired();

      }

    }

    // Add indexes.

    foreach ($schema['indexes'] as $index_name => $columns) {

<?php

namespace Drupal\KernelTests\Core\Field;

use Drupal\Core\Field\BaseFieldDefinition;

use Drupal\entity_test_update\Entity\EntityTestUpdate;

use Drupal\KernelTests\Core\Entity\EntityKernelTestBase;

/**

 * Tests map base fields.

 *

 * @group Field

 */

class MapBaseFieldTest extends EntityKernelTestBase {

  /**

   * The entity definition update manager.

   *

   * @var \Drupal\Core\Entity\EntityDefinitionUpdateManagerInterface

   */

  protected $entityDefinitionUpdateManager;

  /**

   * {@inheritdoc}

   */

  public static $modules = ['entity_test_update'];

  /**

   * {@inheritdoc}

   */

  protected function setUp(): void {

    parent::setUp();

    $this->entityDefinitionUpdateManager = $this->container->get('entity.definition_update_manager');

    // Install every entity type's schema that wasn't installed in the parent

    // method.

    foreach (array_diff_key($this->entityTypeManager->getDefinitions(), array_flip(['user', 'entity_test'])) as $entity_type_id => $entity_type) {

      $this->installEntitySchema($entity_type_id);

    }

  }

  /**

   * Tests uninstalling map item base field.

   */

  public function testUninstallMapItemBaseField() {

    $definitions['data_map'] = BaseFieldDefinition::create('map')

      ->setLabel(t('Data'))

      ->setRequired(TRUE);

    $this->state->set('entity_test_update.additional_base_field_definitions', $definitions);

    $this->entityDefinitionUpdateManager->installFieldStorageDefinition('data_map', 'entity_test_update', 'entity_test', $definitions['data_map']);

    $entity = EntityTestUpdate::create([

      'data_map' => [

        'key' => 'value',

      ],

    ]);

    $entity->save();

    $this->entityDefinitionUpdateManager->uninstallFieldStorageDefinition($definitions['data_map']);

  }

}