SingleDateTimeTimestampWidget.php in Single DateTimePicker 8        
                          
                  
                        
  
  
  
  
  
File
  src/Plugin/Field/FieldWidget/SingleDateTimeTimestampWidget.php
  
    View source  
  <?php
namespace Drupal\single_datetime\Plugin\Field\FieldWidget;
use Drupal\Core\Datetime\DrupalDateTime;
use Drupal\Core\Field\FieldItemListInterface;
use Drupal\Core\Form\FormStateInterface;
use Drupal\datetime\Plugin\Field\FieldType\DateTimeItem;
class SingleDateTimeTimestampWidget extends SingleDateTimeBase {
  
  public function formElement(FieldItemListInterface $items, $delta, array $element, array &$form, FormStateInterface $form_state) {
    $element = parent::formElement($items, $delta, $element, $form, $form_state);
    $date_type = DateTimeItem::DATETIME_TYPE_DATETIME;
    
    $element['value'] = [
      '#title' => $element['#title'],
      '#type' => 'single_date_time',
      '#date_timezone' => date_default_timezone_get(),
      '#default_value' => NULL,
      '#date_type' => $date_type,
      '#required' => $element['#required'],
      '#description' => $element['#description'],
    ];
    
    $format = $this
      ->getSetting('hour_format') === '12h' ? 'Y-m-d h:i:s A' : 'Y-m-d H:i:s';
    
    $element['value'] = array_merge($element['value'], $this
      ->getCommonElementSettings());
    if ($items[$delta]->value) {
      $timestamp = $items[$delta]->value;
      
      $date = DrupalDateTime::createFromTimestamp($timestamp);
      $element['value']['#default_value'] = $date
        ->format($format);
    }
    return $element;
  }
  
  public function massageFormValues(array $values, array $form, FormStateInterface $form_state) {
    foreach ($values as &$item) {
      if (empty($item['value'])) {
        $item['value'] = NULL;
        continue;
      }
      
      if (isset($item['value']) && $item['value'] instanceof DrupalDateTime) {
        $date = $item['value'];
      }
      elseif (isset($item['value']['object']) && $item['value']['object'] instanceof DrupalDateTime) {
        $date = $item['value']['object'];
      }
      elseif (isset($item['value']) && is_string($item['value'])) {
        $date = new DrupalDateTime($item['value']);
      }
      else {
        $date = new DrupalDateTime();
      }
      $item['value'] = $date
        ->getTimestamp();
    }
    return $values;
  }
}