FormTestGroupDetailsForm.php in Drupal 9        
                          
                  
                        
  
  
  
  
File
  core/modules/system/tests/modules/form_test/src/Form/FormTestGroupDetailsForm.php
  
    View source  
  <?php
namespace Drupal\form_test\Form;
use Drupal\Core\Form\FormBase;
use Drupal\Core\Form\FormStateInterface;
class FormTestGroupDetailsForm extends FormBase {
  
  public function getFormId() {
    return 'form_test_group_details';
  }
  
  public function buildForm(array $form, FormStateInterface $form_state, $required = FALSE) {
    $form['details'] = [
      '#type' => 'details',
      '#title' => 'Root element',
      '#open' => TRUE,
      '#required' => !empty($required),
    ];
    $form['meta'] = [
      '#type' => 'details',
      '#title' => 'Group element',
      '#open' => TRUE,
      '#group' => 'details',
    ];
    $form['meta']['element'] = [
      '#type' => 'textfield',
      '#title' => 'Nest in details element',
    ];
    $form['summary_attributes'] = [
      '#type' => 'details',
      '#title' => 'Details element with summary attributes',
      '#summary_attributes' => [
        'data-summary-attribute' => 'test',
      ],
    ];
    return $form;
  }
  
  public function submitForm(array &$form, FormStateInterface $form_state) {
  }
}