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);
}