I'm new to Django but I'm making a game where one of the elements is that players vote for each other.
Here are the models I've set up (relevant fields only)
#models.py
class Game(models.Model):
gamecode = ShortUUIDField(length=4, max_length=4, unique=True)
phasenumber = models.IntegerField(default=1)
isActive = models.BooleanField(default=True)
class Player(models.Model):
game = models.ForeignKey(Game, on_delete=models.CASCADE)
user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
isPlaying = models.BooleanField(default=True)
class PlayerVote(models.Model):
byplayer = models.ForeignKey(Player, on_delete=models.CASCADE)
forplayer = models.ForeignKey(Player, on_delete=models.CASCADE, related_name="voteforplayer")
gamephasenumber = models.IntegerField()
timestamp = models.DateTimeField(auto_now_add=True)
When a user joins a game, they get an entry in the "Player" model and when they cast a vote for another player, an entry is added to the "PlayerVote" model showing which player voted (byplayer) and who they voted for (forplayer).
What I'd like to do is create a QuerySet which contains each player and how many votes they got.
I have tried using annotate which seems to be able to give me a count of the number of votes, but it defaults to joining on the byplayer field, so I end up with the number of votes each player cast, rather than the number of votes each player received.
In SQL I would just do a join on Player.pk = PlayerVote.forplayer.pk, is it possible to do something similar in Django?
Alternatively, I could create an extra model that summarises the votes each player has received and increases by 1 for every vote cast but this seems unnecessary
You can .annotate(…) [Django-doc] with:
from django.db.models import Count
Player.objects.annotate(score=Count('voteforplayer'))The Player objects that arise from this QuerySet will have an extra attribute .score that contains the number of PlayerVotes but with the forplayer_id instead.