Yii 将对象转化成数组

将从数据库查找的对象，转换成数组，并且以设定属性键名称，用到ArrayHelper::toArray 
$posts = Post::find()->limit(10)->all();
    $data = ArrayHelper::toArray($posts, [
        'app\models\Post' => [
            'id',
            'title',
            // the key name in array result => property name
            'createTime' => 'created_at',
            // the key name in array result => anonymous function
            'length' => function ($post) {
                return strlen($post->content);
            },
        ],
    ]);