热门标签问题

<div class="panel-body">

            <?php foreach($hotTags as $hotTag):?>

              <div class="badge badge-tag-cloud">

                <?php if($hotTag->tag_id != $tagId):?>

                  <a href="<?=url('topic/tag');?>?tag=<?=$hotTag->tag_id;?>"><?=$hotTag->tag->name;?></a> (<?=$hotTag->topicNum;?>)

                <?php else:?>

                  <span><?=$hotTag->tag->name;?></span> (<?=$hotTag->topicNum;?>)

                <?php endif;?>

              </div>

            <?php endforeach;?>

          </div>

v这是视图的代码，视频讲解这块，hottag访问tag属性不存在，所以在topictag模型里创建 tag()方法 ，但是创建了还是不行 ，

  public function index(){

    $getData = input('get.');

    $page = isset($getData['page']) ? $getData['page'] : 1;

    $field = isset($getData['field']) ? $getData['field'] : '';

    $order = isset($getData['order']) ? $getData['order'] : '';

    $sortInfo = ['field' => $field, 'order' => $order];

    $pageInfo = TopicModel::getPageInfo($page, config('limitNum'));

    $cacheName = 'index'.$page.$field.$order;

    if (cache($cacheName)) {

      $topics = cache($cacheName);

    } else {

      $topics = TopicModel::getTopics($pageInfo['page'], config('limitNum'), $sortInfo);

      cache($cacheName, $topics, 20);

    }

    $this->assign([

      'topics' => $topics,

      'user' => session('user'),

      'page' => $pageInfo['page'],

      'pageNum' => $pageInfo['pageNum'],

      'showPages' => $pageInfo['showPages'],

      'hotTags' => TopicTagModel::getHotTags(config('hotTagNum')),

    ]);

    echo $this->fetch('index');

  }

这是控制器里代码

  public function tag() {

    return $this->belongsTo('Tag', 'tag_id');

  }

模型 tag方法代码