metatag-8.x-1.x-dev/src/Plugin/Field/FieldType/ComputedMetatagsFieldItem.php

<?php

namespace Drupal\metatag\Plugin\Field\FieldType;

use Drupal\Core\Field\Attribute\FieldType;
use Drupal\Core\Field\FieldItemBase;
use Drupal\Core\Field\FieldStorageDefinitionInterface;
use Drupal\Core\StringTranslation\TranslatableMarkup;
use Drupal\Core\TypedData\DataDefinition;
use Drupal\Core\TypedData\MapDataDefinition;

/**
 * Plugin implementation of the 'metatag_computed' field type.
 */
#[FieldType(
  id: "metatag_computed",
  label: new TranslatableMarkup("Meta tags (computed)"),
  description: new TranslatableMarkup("Computed meta tags"),
  no_ui: TRUE,
  list_class: "\Drupal\metatag\Plugin\Field\MetatagEntityFieldItemList"
)]
class ComputedMetatagsFieldItem extends FieldItemBase {

  /**
   * {@inheritdoc}
   */
  public static function schema(FieldStorageDefinitionInterface $field_definition) {
    return [];
  }

  /**
   * {@inheritdoc}
   */
  public static function propertyDefinitions(FieldStorageDefinitionInterface $field_definition) {
    $properties['tag'] = DataDefinition::create('string')
      ->setLabel(t('Tag'))
      ->setRequired(TRUE);
    $properties['attributes'] = MapDataDefinition::create()
      ->setLabel(t('Name'))
      ->setRequired(TRUE);
    return $properties;
  }

  /**
   * {@inheritdoc}
   */
  public function isEmpty() {
    $value = $this->get('attributes')->getValue();
    return $value === NULL || $value === [];
  }

}