Laravel 5.3 withCount（）嵌套关系

问题描述

模型结构如下

教程 - >（hasMany）章 - >（hasMany）视频

Tutorial -> (hasMany) Chapters -> (hasMany) videos

如何使用laravel 5.3的withCount（）方法来加载教程模型中的视频数量（video_count）

How can we load number of videos (video_count) from Tutorial Model with laravel 5.3's withCount() method

我尝试过：

Tutorial::withCount('chapters')
->withCount('chapters.videos') // this gives error: Call to undefined method Illuminate\Database\Query\Builder::chapters.videos()
->all();

修改

这个工作，任何更好的解决方案？

This works, Any Better solution?

Tutorial::withCount('chapters')
->with(['chapters' => function($query){
    $query->withCount('videos');
}])
->all();

推荐答案

你只能做一个 withCount（）在模型的定义关系上。

You can only do a withCount() on a defined relation of the model.

然而，关系可以是 hasManyThrough 这将实现你以后的任务。

However, a relationship can be hasManyThrough which would achieve what you are after.

class Tutorial extends Model
{
    function chapters()
    {
        return $this->hasMany('App\Chapter');
    }

    function videos()
    {
        return $this->hasManyThrough('App\Video', 'App\Chapter');
    }
}

然后你可以做：

教程:: withCount（['章节'，'视频']）

文件：

• https://laravel.com/docs/5.3/eloquent-relationships#has-many-through

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