9. Providing a user interface for configuration entities

9.1. Add a list of event types

• Add a src/Controller/EventTypeListBuilder.php file with the following:

  <?php
  
  namespace Drupal\event\Controller;
  
  use Drupal\Core\Entity\EntityInterface;
  use Drupal\Core\Entity\EntityListBuilder;
  
  class EventTypeListBuilder extends EntityListBuilder {
  
    public function buildHeader() {
      $header = [];
      $header['label'] = $this->t('Label');
      return $header + parent::buildHeader();
    }
  
    public function buildRow(EntityInterface $entity) {
      $row = [];
      $row['label'] = $entity->label();
      return $row + parent::buildRow($entity);
    }
  
  }

• Add the following use statements to src/Entity/EventType.php:

  use Drupal\entity\EntityAccessControlHandler;
  use Drupal\event\Controller\EventTypeListBuilder;
  use Drupal\entity\Menu\EntityCollectionLocalActionProvider;
  use Drupal\entity\EntityPermissionProvider;
  use Drupal\entity\Routing\DefaultHtmlRouteProvider;

• Add the following to the attributes in src/Entity/EventType.php:

  handlers: [
    'access' => EntityAccessControlHandler::class,
    'list_builder' => EventTypeListBuilder::class,
    'local_action_provider' => [
      'collection' => EntityCollectionLocalActionProvider::class,
    ],
    'permission_provider' => EntityPermissionProvider::class,
    'route_provider' => [
      'default' => DefaultHtmlRouteProvider::class,
    ],
  ],
  links: [
    'collection' => '/admin/structure/event-types',
  ],
  admin_permission: 'administer event type',

• Add the following to event.links.menu.yml:

  entity.event_type.collection:
    title: 'Event types'
    route_name: entity.event_type.collection
    parent: system.admin_structure

• Rebuild caches

  Run drush cache:rebuild

• Verify that there is a Event types menu link in the toolbar menu

• Visit /admin/structure/event-types

  Note that a listing of event types is shown.

9.2. Add forms for event types

In contrast to content entities, configuration entities do not have the ability to use widgets for their forms, so we need to provide the respective form elements ourselves.

• Add a src/Form/EventTypeForm.php file with the following:

  <?php
  
  namespace Drupal\event\Form;
  
  use Drupal\Core\Entity\EntityForm;
  use Drupal\Core\Entity\EntityTypeInterface;
  use Drupal\Core\Form\FormStateInterface;
  
  class EventTypeForm extends EntityForm {
  
    public function form(array $form, FormStateInterface $form_state) {
      $form = parent::form($form, $form_state);
  
      $event_type = $this->getEntity();
  
      $form['label'] = [
        '#type' => 'textfield',
        '#title' => $this->t('Label'),
        '#default_value' => $event_type->label(),
        '#required' => TRUE,
      ];
  
      $form['id'] = [
        '#type' => 'machine_name',
        '#title' => $this->t('ID'),
        '#maxlength' => EntityTypeInterface::BUNDLE_MAX_LENGTH,
        '#default_value' => $event_type->id(),
        '#machine_name' => [
          'exists' => [$event_type->getEntityType()->getClass(), 'load'],
        ],
        '#disabled' => !$event_type->isNew(),
      ];
  
      return $form;
    }
  
    public function save(array $form, FormStateInterface $form_state) {
      parent::save($form, $form_state);
  
      $entity = $this->getEntity();
      $entity_type = $entity->getEntityType();
  
      $arguments = [
        '@entity_type' => $entity_type->getSingularLabel(),
        '%entity' => $entity->label(),
        'link' => $entity->toLink($this->t('Edit'), 'edit-form')->toString(),
      ];
  
      $this->logger($entity->getEntityTypeId())->notice('The @entity_type %entity has been saved.', $arguments);
      $this->messenger()->addMessage($this->t('The @entity_type %entity has been saved.', $arguments));
  
      $form_state->setRedirectUrl($entity->toUrl('collection'));
    }
  
  }

• Add the following use statements to src/Entity/EventType.php:

  use Drupal\event\Form\EventTypeForm;
  use Drupal\Core\Entity\EntityDeleteForm;

• Add the following to the handlers section of the attributes in src/Entity/EventType.php:

  'form' => [
      'add' => EventTypeForm::class,
      'edit' => EventTypeForm::class,
      'delete' => EntityDeleteForm::class,
  ]

• Add the following to the links section of the attributes in src/Entity/EventType.php:

  'add-form' => '/admin/structure/event-types/add',
  'edit-form' => '/admin/structure/event-types/manage/{event_type}',
  'delete-form' => '/admin/structure/event-types/manage/{event_type}/delete',

• Add the following to event.links.task.yml:

  entity.event_type.edit_form:
    title: 'Edit'
    route_name: entity.event_type.edit_form
    base_route: entity.event_type.edit_form
  entity.event_type.delete_form:
    title: 'Delete'
    route_name: entity.event_type.delete_form
    base_route: entity.event_type.edit_form

• Rebuild caches

  Run drush cache:rebuild

• Verify that a local action appears to add an event type

• Add an event type.

• Edit an event type.

• Verify that Edit and Delete local tasks are shown.

• Delete an event type.