starry_rating-1.0.x-dev/src/Plugin/Field/FieldFormatter/StarRatingFormatter.php

<?php

namespace Drupal\starry_rating\Plugin\Field\FieldFormatter;

use Drupal\Core\Field\Attribute\FieldFormatter;
use Drupal\Core\Field\FormatterBase;
use Drupal\Core\Field\FieldItemListInterface;
use Drupal\Core\StringTranslation\TranslatableMarkup;

/**
 * Formatter to show star rating widget.
 */
#[FieldFormatter(
  id: 'starry_rating_rating_formatter',
  label: new TranslatableMarkup('Star rating formatter'),
  field_types: ['starry_rating'],
)]
class StarRatingFormatter extends FormatterBase {

  /**
   * {@inheritdoc}
   */
  public function viewElements(FieldItemListInterface $items, $langcode) {
    $elements = [];

    foreach ($items as $delta => $item) {
      $value = $item->value ?? 0;
      $elements[$delta] = [
        '#markup' => '<div class="star-rating" data-read-only="true" data-stars="' . $value . '"></div>',
        '#attached' => ['library' => ['starry_rating/star_rating']],
      ];
    }

    return $elements;
  }

}