Django Model how to order by vote time?

Question

So I have three models, User, Post, and UserVote:

User is default django.contrib.auth user

Post definition:

class Post(models.Model):
    num_likes = models.IntegerField(default=0)
    num_dislikes = models.IntegerField(default=0)
 
    # when deleting users, we should simply set user.is_active to False,
    # that way this doesn't break
    user = models.ForeignKey(User, on_delete=models.CASCADE)

    text = models.CharField(max_length=200, default="")

UserVote:

class Action(models.TextChoices):
    UP = 'u'
    DOWN = 'd'

class UserVotes(models.Model):
    voter = models.ForeignKey(User, on_delete=models.CASCADE)
    item = models.ForeignKey(Post, on_delete=models.CASCADE)
    type = models.CharField(max_length=2, choices=Action.choices, default=Action.UP)
    time = models.DateTimeField('time voted on', default=timezone.now)

    class Meta:
        unique_together = ('voter', 'item')

On a user's profile page, I want to return the posts a user upvoted in descending order of when their vote was cast. I'm kind of lost here. I can return the posts a user voted on that aren't theirs as such:

def get_users_liked_posts(user_id):
    Post.objects.filter(uservotes__voter__id=user_id, uservotes__type=Action.UP).exclude(user_id=user_id)

But I'm not sure what to pass to order_by ? It would be something like -uservotes__time but how would I specify that I want to order by a particular user_ids uservotes? I could also retrieve all the uservotes corresponding to a user and order those, but then how would I turn all those into Posts?

EDIT: So after some digging, I found the select_related function: https://www.kite.com/python/docs/django.db.models.QuerySet.select_related

which allows me to do this:

def get_users_liked_posts(user_id):
    # note: position of select_related in query is irrelevant
    upvotes = UserVotes.objects.filter(voter_id=user_id, type=Action.UP).exclude(item__user_id=user_id).order_by('-time').select_related('item')
    return [upvote.item for upvote in upvotes]

It is performant, but I feel like there should be a built in way to do what I'm trying to? I

EDIT2: I'm so dumb, I forgot that I can just .order_by(-time) since I already have the filter in place, whoops

Answer 1

The time when the vote was created is the best attribute to use to order your votes. Use the ordering right in your model definition as such:

class Meta:
    unique_together = ('voter', 'item')
    ordering = ['-time']