TimestampItem.php

<?php

namespace Drupal\Core\Field\Plugin\Field\FieldType;

use Drupal\Core\Field\FieldDefinitionInterface;
use Drupal\Core\Field\FieldItemBase;
use Drupal\Core\Field\FieldStorageDefinitionInterface;
use Drupal\Core\TypedData\DataDefinition;

/**
 * Defines the 'timestamp' entity field type.
 *
 * @FieldType(
 *   id = "timestamp",
 *   label = @Translation("Timestamp"),
 *   description = {
 *     @Translation("Ideal for using date and time calculations or comparisons"),
 *     @Translation("Date and time stored in the form of seconds since January 1, 1970 (UTC)"),
 *     @Translation("Compact and efficient for storage, sorting and calculations"),
 *   },
 *   category = "date_time",
 *   default_widget = "datetime_timestamp",
 *   default_formatter = "timestamp",
 *   constraints = {
 *     "ComplexData" = {
 *       "value" = {
 *         "Range" = {
 *           "min" = "-2147483648",
 *           "max" = "2147483648",
 *         }
 *       }
 *     }
 *   }
 * )
 */
class TimestampItem extends FieldItemBase {

  /**
   * {@inheritdoc}
   */
  public static function propertyDefinitions(FieldStorageDefinitionInterface $field_definition) {
    $properties['value'] = DataDefinition::create('timestamp')
      ->setLabel(t('Timestamp value'))
      ->setRequired(TRUE);
    return $properties;
  }

  /**
   * {@inheritdoc}
   */
  public static function schema(FieldStorageDefinitionInterface $field_definition) {
    return [
      'columns' => [
        'value' => [
          'type' => 'int',
        ],
      ],
    ];
  }

  /**
   * {@inheritdoc}
   */
  public static function generateSampleValue(FieldDefinitionInterface $field_definition) {

    // Pick a random timestamp in the past year.
    $timestamp = \Drupal::time()
      ->getRequestTime() - mt_rand(0, 86400 * 365);
    $values['value'] = $timestamp;
    return $values;
  }

}