Laravel 5.3 withCount()嵌套关系

Question

模型结构如下

教程 - >(hasMany)章节 - >(hasMany)视频

如何使用laravel 5.3的withCount()方法从Tutorial Model加载视频数量(video_count)

我试过了:

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

编辑

这有效,任何更好的解决方案？

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

Answer 1

您只能withCount()对模型的已定义关系执行操作.

然而,一种关系可以hasManyThrough实现你所追求的目标.

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

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

然后你可以这样做:

withCount()

文档:

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