Laravel排序最后的记录

问题描述

我正在建立一个论坛.

在主页上，我想显示每个论坛的最新回复.

In the main page, I want to show the last reply for each forum.

层次结构是这样的:

论坛

hasMany('App \ Topic')

hasMany('App\Topic')

hasManyThrough('App \ Topic'，'App \ Repley')

hasManyThrough('App\Topic', 'App\Repley')

主题

belongsTo('App \ Forum')

belongsTo('App\Forum')

hasMany('App \ Reply')

hasMany('App\Reply')

回复

belongsTo('App \ Topic')

belongsTo('App\Topic')

我这样做了:

 $forum->replies()->orderBy('created_at', 'desc')->first()

它奏效了.但我想按主题和答复进行排序.如果我在最后一个回复之后发布新主题，我希望该内容作为最后一个回复.

And it worked. But I want to sort by topics and replies.If I post new topic after the last reply, I want that show as the last reply.

更新:我做到了，它奏效了.但是还有其他方法吗?

Update:I did this, and it work. But is there any other way?

public function last() {
    $topic = $this->topics->sortByDesc('created_at')->first();
    $post = $this->replies->sortByDesc('created_at')->first();

    return ($topic->created_at > $post->created_at) ? $topic : $post;
}

推荐答案

我建议的一种解决方案是让答复的 touch 主题. https://laravel.com/docs/5.3/eloquent-relationships#touching-parent-timestamps

One solution I would suggest is to have the replied touch the topics.https://laravel.com/docs/5.3/eloquent-relationships#touching-parent-timestamps

通过这种方式，您始终可以按主题的 updated_at 进行排序，因为无论何时创建/编辑回复，都会同时更新主题.

This way you can always order by the Topic's updated_at because whenever a reply is created/edited it will update the Topic as well.

要实现此目的，您只需添加:

To achieve this you would just need to add:

protected $touches = ['topic'];

以上假设假设答复模型中主题关系的方法名称为 topic().

The above is assuming that the method name for the topics relationship in the replies model is topic().

希望这会有所帮助！

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