cloud-8.x-2.0-beta1/modules/cloud_service_providers/k8s/src/Plugin/Field/FieldFormatter/KeyValueFormatter.php

<?php

namespace Drupal\k8s\Plugin\Field\FieldFormatter;

use Drupal\Core\Field\FieldItemListInterface;
use Drupal\Core\Field\FormatterBase;

/**
 * Plugin implementation of the 'key_value_formatter' formatter.
 *
 * @FieldFormatter(
 *   id = "key_value_formatter",
 *   label = @Translation("Key value formatter"),
 *   field_types = {
 *     "key_value"
 *   }
 * )
 */
class KeyValueFormatter extends FormatterBase {

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

    foreach ($items as $item) {
      /* @var \Drupal\k8s\Plugin\Field\FieldType\KeyValue $item */
      if (!$item->isEmpty()) {
        $rows[] = [
          $item->item_key,
          $item->item_value,
        ];
      }
    }

    if (count($rows)) {
      $elements[0] = [
        '#theme' => 'table',
        '#header' => [
          $this->t('Key'),
          $this->t('Value'),
        ],
        '#rows' => $rows,
      ];
    }

    return $elements;
  }

}