DateTimeTimeAgoFormatter.php

<?php

namespace Drupal\datetime\Plugin\Field\FieldFormatter;

use Drupal\Core\Datetime\DrupalDateTime;
use Drupal\Core\Field\FieldItemListInterface;
use Drupal\Core\Field\Plugin\Field\FieldFormatter\TimestampAgoFormatter;

/**
 * Plugin implementation of the 'Time ago' formatter for 'datetime' fields.
 *
 * @FieldFormatter(
 *   id = "datetime_time_ago",
 *   label = @Translation("Time ago"),
 *   field_types = {
 *     "datetime"
 *   }
 * )
 */
class DateTimeTimeAgoFormatter extends TimestampAgoFormatter {
    
    /**
     * {@inheritdoc}
     */
    public function viewElements(FieldItemListInterface $items, $langcode) {
        $elements = [];
        foreach ($items as $delta => $item) {
            $date = $item->date;
            $output = [];
            if (!empty($item->date)) {
                $output = $this->formatDate($date);
            }
            $elements[$delta] = $output;
        }
        return $elements;
    }
    
    /**
     * Formats a date/time as a time interval.
     *
     * @param \Drupal\Core\Datetime\DrupalDateTime|object $date
     *   A date/time object.
     *
     * @return array
     *   The formatted date/time string using the past or future format setting.
     */
    protected function formatDate(DrupalDateTime $date) {
        return parent::formatTimestamp($date->getTimestamp());
    }

}