EntityTestComputedField.php

<?php

namespace Drupal\entity_test\Entity;

use Drupal\Core\Entity\EntityTypeInterface;
use Drupal\Core\Field\BaseFieldDefinition;
use Drupal\entity_test\Plugin\Field\ComputedReferenceTestFieldItemList;
use Drupal\entity_test\Plugin\Field\ComputedTestFieldItemList;

/**
 * An entity used for testing computed field values.
 *
 * @ContentEntityType(
 *   id = "entity_test_computed_field",
 *   label = @Translation("Entity Test computed field"),
 *   base_table = "entity_test_computed_field",
 *   handlers = {
 *     "views_data" = "Drupal\entity_test\EntityTestViewsData"
 *   },
 *   entity_keys = {
 *     "id" = "id",
 *     "label" = "name",
 *   },
 *   admin_permission = "administer entity_test content",
 *   links = {
 *     "add-form" = "/entity_test_computed_field/add",
 *   },
 * )
 */
class EntityTestComputedField extends EntityTest {
    
    /**
     * {@inheritdoc}
     */
    public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
        $fields = parent::baseFieldDefinitions($entity_type);
        $fields['computed_string_field'] = BaseFieldDefinition::create('string')->setLabel('Computed Field Test')
            ->setComputed(TRUE)
            ->setClass(ComputedTestFieldItemList::class);
        $fields['computed_reference_field'] = BaseFieldDefinition::create('entity_reference')->setLabel('Computed Reference Field Test')
            ->setComputed(TRUE)
            ->setSetting('target_type', 'entity_test')
            ->setClass(ComputedReferenceTestFieldItemList::class);
        return $fields;
    }

}