上面为模型部分

<div class="row">
    <div class="col-sm-12 col-md-6">   <?php if($prev){ ?>   <a href="<?= Yii::$app->urlManager->createUrl(['sites/view','id'=>$prev->id]); ?>">上一篇： <?= $prev->sitename; ?> </a>
    <?php }else{ echo "暂无";} ?>
    </div>
    <div class="col-sm-12 col-md-6">
        <?php  // var_dump($next);?>
        <?php if($next){ ?>  <a href="<?= Yii::$app->urlManager->createUrl(['sites/view','id'=>$next->id]); ?>"> 下一篇：<?=  $next->sitename; ?>  </a>
        <?php }else{ echo "暂无";} ?>
    </div>
</div>

视图部分

public function actionView($id)
{
    $model=$this->findModel($id);
    $prev = $model->getPrev();
    $next = $model->getNext();
    return $this->render('view', [
        'model' => $this->findModel($id),
        'prev' => $prev,
        'next' => $next,
    ]);
}

控制器部分

亲，您一个java的项目，拿到yii社区来推广，有点惆怅吧

[root@localhost moblog]# composer update
Loading composer repositories with package information
Updating dependencies (including require-dev)
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - The requested package npm-asset/bootstrap-markdown could not be found in any version, there may be a typo in the package name.
  Problem 2
    - The requested package npm-asset/markdown could not be found in any version, there may be a typo in the package name.
  Problem 3
    - yiisoft/yii2 2.0.7 requires bower-asset/jquery 2.2.*@stable | 2.1.*@stable | 1.11.*@stable -> no matching package found.
    - yiisoft/yii2 2.0.6 requires bower-asset/jquery 2.1.*@stable | 1.11.*@stable -> no matching package found.
    - yiisoft/yii2 2.0.5 requires bower-asset/jquery 2.1.*@stable | 1.11.*@stable -> no matching package found.
    - yiisoft/yii2 2.0.4 requires bower-asset/jquery 2.1.*@stable | 1.11.*@stable -> no matching package found.
    - yiisoft/yii2 2.0.3 requires bower-asset/jquery 2.1.*@stable | 1.11.*@stable -> no matching package found.
    - yiisoft/yii2 2.0.2 requires bower-asset/jquery 2.1.*@stable | 1.11.*@stable -> no matching package found.
    - yiisoft/yii2 2.0.1 requires bower-asset/jquery 2.1.*@stable | 1.11.*@stable -> no matching package found.
    - yiisoft/yii2 2.0.0 requires bower-asset/jquery 2.1.*@stable | 1.11.*@stable -> no matching package found.
    - Installation request for yiisoft/yii2 * -> satisfiable by yiisoft/yii2[2.0.0, 2.0.1, 2.0.2, 2.0.3, 2.0.4, 2.0.5, 2.0.6, 2.0.7].

Potential causes:
 - A typo in the package name
 - The package is not available in a stable-enough version according to your minimum-stability setting
   see <https://getcomposer.org/doc/04-schema.md#minimum-stability> for more details.

Read <https://getcomposer.org/doc/articles/troubleshooting.md> for further common problems.

这个包是不是该更新了还是我的环境有问题啊

大赞；最近刚好在看这块东西