drupal 8条件字段

我想在drupal 8中将省和城市字段添加到用户实体.通过更改省份,应更新城市列表.在drupal 7中我用条件字段模块完成了这个,但是这个模块还没有为drupal 8做好准备.在drupal 8中这样做的正确方法是什么？我应该添加字段,然后将jquery添加到我的注册模板中,或者是否有更好的标准方法来执行此操作.谢谢.

使用一点(PHP)代码,可以使用Drupal的状态处理来明确说明哪些字段应该显示或隐藏给定哪些条件.

例如,当在类别字段中选择设计(术语ID 4)等时,这将显示设计类型,设计位置和设计规程字段:

/**
 * Implements hook_form_alter().
 *
 * On Work node add and edit, set only selected category's associated
 * vocabularies as visible.
 */
function mass_form_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_state, $form_id) {
  if ($form_id != 'node_work_form' && $form_id != 'node_work_edit_form') {
    return;
  }
  if (isset($form['field_category'])) {
    $states_when_category_is_design = array(
      'visible' => array(
        ':input[name="field_category"]' => array('value' => '4'),
      ),
    );

    $states_when_category_is_advocacy = array(
      'visible' => array(
        ':input[name="field_category"]' => array('value' => '19'),
      ),
    );

    $states_when_category_is_research = array(
      'visible' => array(
        ':input[name="field_category"]' => array('value' => '25'),
      ),
    );

    if (isset($form['field_design_type'])) {
      $form['field_design_type']['#states'] = $states_when_category_is_design;
    }

    if (isset($form['field_design_location'])) {
      $form['field_design_location']['#states'] = $states_when_category_is_design;
    };

    if (isset($form['field_design_discipline'])) {
      $form['field_design_discipline']['#states'] = $states_when_category_is_design;
    };

    if (isset($form['field_advocacy_type'])) {
      $form['field_advocacy_type']['#states'] = $states_when_category_is_advocacy;
    };

    if (isset($form['field_research_type'])) {
      $form['field_research_type']['#states'] = $states_when_category_is_research;
    };
  }
}

(这个代码是从Mauricio Dinarte,也就是我的同事和Agaric的同事兼所有者dinarcon无耻地偷走的.)