在Django中注释多对多关系

问题描述

我有两个模型User和VideoData。这两个模型包含每个用户的详细信息以及该用户观看的视频。我使用了多对多关系。现在，我想按用户数量过滤观看次数最多的10个视频。

I have two models User and VideoData. These two models contain the details of each user and watched videos by that user. I used many-to-many relation. Now I want to filter top 10 videos watch by number of users.

class User(models.Model):
    user_id = models.CharField(max_length=40,unique=True)
    user_name = models.CharField(max_length=40)
    user_email = models.EmailField()
    user_city = models.CharField(max_length=40)
    videos_watched = models.ManyToManyField('VideoData', through='WatchedVideo')
    class Meta:
        ordering = ['user_id']
        verbose_name = 'User MetaData'
        verbose_name_plural = 'Users MetaData'
    def __unicode__(self):
        return self.user_id

class VideoData(models.Model):
    video_id = models.CharField(max_length=40,unique=True)
    video_name = models.CharField(max_length=40)
    class Meta:
        verbose_name = 'User_Video MetaData'
        verbose_name_plural = 'Users_Video MetaData'
    def __unicode__(self):
        return self.video_name

class WatchedVideo(models.Model):
    user = models.ForeignKey(User, to_field = 'user_id')
    videoData = models.ForeignKey(VideoData, to_field = 'video_id')
    time  = models.PositiveIntegerField(null = True)

我如何注释前10个视频以及观看这些视频的用户数量？

How can i annotate for top 10 videos and number of users watched those videos??

推荐答案

使用Django ORM中的Count函数：

Use Count function from django ORM:

    VideoData.objects.annotate(
        watches_count=models.Count('user_set')
    ).order_by('-watches_count')[:10]

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