public function acProblem()
{
$cid = '16';
$posts = Post::find()->where(['category_id' => $cid])->limit(10)->orderBy('id desc')->all();
return $this->view('problem', ['posts' => $posts]);
}
/**
* @return \yii\db\ActiveQuery
*/
public function getPost()
{
return $this->hasMany(Post::className(), ['category_id' => 'id']);
}