laravel-admin select框默认选中的方法

protected function form()
{
  return Admin::form(Member::class, function (Form $form) {

    // $form- display('id', 'ID');
    $form- text('mac', '终端mac');
    $form- text('phone', '手机号');
    $form- text('password', '密码');
    //判断是不是edit
    $id = Request::route('member');
    $place_id ='';
    $rule_id = '';
    if ($id)
    {
      $model = $form- model()- find($id);
      $place_id = $model- place_id;
      $rule_id = $model- rule_id;
    }
    $form- select('place_id','所属场所')- options("/api/getPlace/$place_id");
    $form- select('rule_id', '规则')- options("/api/getRule/$rule_id");
  });
}

//api的实现
public function getPlace(Request $request)
{
  $name = $request- get('p');
  $id = $request- id;
  $where = [];
  if ($name)
  {
    $where = ['name','like',"%$name%"];
  }
  $places = Place::where($where)- get();
  $result = [];
  foreach ($places as $key= $value)
  {
    $result[$key]['id'] = $value- Id;
    $result[$key]['text'] = $value- name;
    if ($value- Id == $id)
    {
      $result[$key]['selected'] = true;
    }
  }
    if (!$id)
    {
      array_unshift($result,['id'= ' ','text'= '请选择场所','selected'= true]);
    }else{
      array_unshift($result,['id'= ' ','text'= '请选择场所']);
    }
  return response()- json($result);
}