and adds attributes such as classes or * an HTML ID. * * Usage example: * @code * $form['needs_accommodation'] = array( * '#type' => 'checkbox', * '#title' => $this->t('Need Special Accommodations?'), * ); * * $form['accommodation'] = array( * '#type' => 'container', * '#attributes' => array( * 'class' => 'accommodation', * ), * '#states' => array( * 'invisible' => array( * 'input[name="needs_accommodation"]' => array('checked' => FALSE), * ), * ), * ); * * $form['accommodation']['diet'] = array( * '#type' => 'textfield', * '#title' => $this->t('Dietary Restrictions'), * ); * @endcode * * @RenderElement("container") */ class Container extends RenderElement { /** * {@inheritdoc} */ public function getInfo() { $class = get_class($this); return [ '#process' => [ [$class, 'processGroup'], [$class, 'processContainer'], ], '#pre_render' => [ [$class, 'preRenderGroup'], ], '#theme_wrappers' => ['container'], ]; } /** * Processes a container element. * * @param array $element * An associative array containing the properties and children of the * container. * @param \Drupal\Core\Form\FormStateInterface $form_state * The current state of the form. * @param array $complete_form * The complete form structure. * * @return array * The processed element. */ public static function processContainer(&$element, FormStateInterface $form_state, &$complete_form) { // Generate the ID of the element if it's not explicitly given. if (!isset($element['#id'])) { $element['#id'] = HtmlUtility::getUniqueId(implode('-', $element['#parents']) . '-wrapper'); } return $element; } }