webform_isElementVisibleThroughParent.partial.php

  /**
   * Determine if an element is visible by checking visiblity of parents.
   *
   * A helper around 
   * \Drupal::service('webform_submission.conditions_validator')->isElementVisible
   * @param  Array  $element
   *   Webform element.
   * @param  \Drupal\Core\Form\FormStateInterface $form_state 
   *   Form state object.
   * @param  Array $complete_form
   *   Form array.
   * @return boolean
   *   True if all parent elements and the element itself if visible,
   *   else FALSE.
   */
  public static function isElementVisibleThroughParent($element, FormStateInterface $form_state, &$complete_form) {
    // Build webform submission and get conditions validator service.
    $form_object = $form_state->getFormObject();
    $webform_submission = $form_object->buildEntity($complete_form, $form_state);
    $conditions_validator = \Drupal::service('webform_submission.conditions_validator');
    
    // Loop through each of parents elements to work out visibility.
    $parents = $element['#webform_parents'];
    $parent_container = $complete_form['elements'];
    foreach ($parents as $parent) {
      $parent_container = $parent_container[$parent];
      $is_visible = $conditions_validator->isElementVisible($parent_container, $webform_submission);
      // Return FALSE as soon as an invisible element is found.
      // The element itself will be invisible if its parent is.
      if (!$is_visible) {
        return FALSE;
      }
    }
    
    // If all parents are visible, then return visibility of the element itself.
    return $conditions_validator->isElementVisible($element, $webform_submission);
  }

  /**
   * {@inheritdoc}
   */
  public static function validateWebformComposite(&$element, FormStateInterface $form_state, &$complete_form) {
    // IMPORTANT: Must get values from the $form_states since sub-elements
    // may call $form_state->setValueForElement() via their validation hook.
    // @see \Drupal\webform\Element\WebformEmailConfirm::validateWebformEmailConfirm
    // @see \Drupal\webform\Element\WebformOtherBase::validateWebformOther
    $value = NestedArray::getValue($form_state->getValues(), $element['#parents']);
    $element_key = end($element['#parents']);

    // If the element or any of its parent containers are hidden by conditions,
    // Bypass validation and clear any required element errors generated
    // for this element.
    if (!self::isElementVisibleThroughParent($element, $form_state, $complete_form)) {
      $form_errors = $form_state->getErrors();
      $form_state->clearErrors();
      foreach($form_errors as $error_key => $error_value) {
        if (strpos($error_key, $element_key . ']') !== 0) {
          $form_state->setErrorByName($error_key, $error_value);
        }
      }
      return;
    }
}