EntityReferenceTestHooks.php

<?php

declare (strict_types=1);
namespace Drupal\entity_reference_test\Hook;

use Drupal\Core\Field\BaseFieldDefinition;
use Drupal\Core\Entity\EntityTypeInterface;
use Drupal\Core\Hook\Attribute\Hook;
use Drupal\Core\StringTranslation\StringTranslationTrait;

/**
 * Hook implementations for entity_reference_test.
 */
class EntityReferenceTestHooks {
  use StringTranslationTrait;
  
  /**
   * Implements hook_entity_base_field_info().
   */
  public function entityBaseFieldInfo(EntityTypeInterface $entity_type) : array {
    $fields = [];
    if ($entity_type->id() === 'entity_test') {
      $fields['user_role'] = BaseFieldDefinition::create('entity_reference')->setLabel($this->t('User role'))
        ->setDescription($this->t('The role of the associated user.'))
        ->setSetting('target_type', 'user_role')
        ->setSetting('handler', 'default');
    }
    return $fields;
  }
  
  /**
   * Implements hook_entity_base_field_info_alter().
   */
  public function entityBaseFieldInfoAlter(&$fields, EntityTypeInterface $entity_type) : void {
    if ($entity_type->id() === 'entity_test') {
      // Allow user_id field to use configurable widget.
      $fields['user_id']->setSetting('handler', 'default')
        ->setDisplayOptions('form', [
        'type' => 'entity_reference_autocomplete',
        'weight' => 0,
      ])
        ->setDisplayConfigurable('form', TRUE);
    }
  }

}