How to get the most liked users in django rest-api

So I have a social media app, where users can like the posts of other users. Now I want to fetch the top 20 users who have received the most number of likes. I am pretty much confused how to query my Likes Model

My LIKES MODEL

class PostLike(models.Model):
    user_who_liked = models.ForeignKey(User, on_delete=models.CASCADE)
    post_liked = models.ForeignKey(Post, on_delete=models.CASCADE)
    liked_on = models.DateTimeField(default=timezone.now)

SIMPLIFIED POST MODEL

class Post(models.Model):
    id = models.AutoField(primary_key=True)
    user = models.ForeignKey(User, on_delete=models.CASCADE)
    caption = models.TextField()
    date = models.DateTimeField(default=timezone.now)
    likes = models.ManyToManyField(
        User, blank=True, through=PostLike)
    image = models.TextField()

    class Meta:
        ordering = ['-id']

SIMPLIFIED USER MODEL

class User(AbstractBaseUser, PermissionsMixin):
    email = models.EmailField(unique=True)
    user_name = models.CharField(max_length=100, unique=True)
    date = models.DateTimeField(default=timezone.now)
    profile_picture = models.TextField(
        default="https://www.kindpng.com/picc/m/24-248253_user-profile-default-image-png-clipart-png-download.png")
    bio = models.CharField(max_length=200, default="")
    objects = CustomManger()

    def __str__(self):
        return self.user_name

** My View **

@api_view(["GET"])
@permission_classes([IsAuthenticated])
def leaderboard(request):
    # I dont know how to query the PostLike model now to get the most liked users
    pass

Answer

First I changed the user attribute in your Post model, I added related_name because otherwise the related names were clashing. This is the definition I used, otherwise your models are unchanged.

user = models.ForeignKey(User, on_delete=models.CASCADE, related_name='author')

I.e. the posts by a user are accessible on User via the author attribute.

The following query gives you the top 20 users by number of likes they received:

User.objects.annotate(num_likes=Count('author__likes')).order_by('-num_likes')[:20]

Explanation:

• Query User model and
• annotate each user by doing a count:
  • author leads to the posts by the user
  • likes follows to PostLike and counts all likes which are associated with a post by the user
• then order by number of likes descending,
• and limit the number of retrieved objects to 20.