问 Laravel 5.8 -如何排序(orderBy)多个关系

<?php
//sort method:
public function mostPopular()
        $serials = Serial::with(['series.episodes.video' => function ($query) {
            $query->withCount(['videoViews' => function($query) {
            }])->orderBy('video_views_count', 'desc');
        }])->get();
        return $serials;
//Serial model:
public function series()
   return $this->hasMany(Series::class);
//Series model:
public function episodes()
   return $this->hasMany(Episode::class);
public function serial()
   return $this->belongsTo(Serial::class);
//Episode model:
public function video()
   return $this->hasOne(Video::class);
public function series()
   return $this->belongsTo(Series::class);
//Video model:
public function videoViews()
   return $this->hasMany(VideoView::class);
public function episode()