Django query using filters

Question

I have 3 models in django:

class Movie(models.Model):
    mid = models.IntegerField(primary_key = True)
    name = models.CharField(max_length = 100)

class User(models.Model):
    username = models.CharField(max_length=128, null=True)
    uid = models.CharField(max_length=100)
    movie = models.ManyToManyField(Movie, through = "Vote")

class Vote(models.Model):
    movie = models.ForeignKey(Movie)
    user = models.ForeignKey(User)
    rating = models.IntegerField()

here rating = 0/1, 0 means dislike, 1 means like i want to make some queries using filters:

find out all movies that a current user likes. For that i use this following 2 queries, but none of them work. In both cases it gives erroneous results

ans = Movie.objects.filter(vote__user = self).filter(vote__rating = 1)

ans = Movie.objects.filter(user__uid = self.uid).filter(vote__rating = 1)
I have a list of users in an array ids. I want to find out how many users from this list like a particular movie? i tried this, but this is also incorrect:

ret = User.objects.filter(uid__in = ids).filter(vote__movie = mov).filter(vote__rating = 1)

can somebody please help me with these 2 queries?

In #1, what is self? Can you show the whole method? What objects do you get when you do this? — Lou Franco
– Lou Franco, Commented May 8, 2011 at 23:49

dting · Accepted Answer · 2011-05-09 01:42:55Z

I'd also suggest letting django assign the model's id's but if you are using a legacy database or for some other reason need to assign the id's you can query like so:

# uid is some uid
user = User.objects.get(uid=uid)
likes = Movie.objects.filter(vote__user=user, vote__rating=1)

or

likes = Movie.objects.filter(vote__user__uid=some_uid, vote__rating=1)

count of people in the list of users who like a specific movie:

>>> uids = ['1','2','3']
>>> # if mov is a Movie instance
>>> votes = Vote.objects.filter(user__uid__in=uids, movie=mov, rating=1)
>>> print votes.query
SELECT "so1_vote"."id", "so1_vote"."movie_id", "so1_vote"."user_id", "so1_vote"."rating" FROM "so1_vote" INNER JOIN "so1_user" ON ("so1_vote"."user_id" = "so1_user"."id") WHERE ("so1_user"."uid" IN (1, 2, 3) AND "so1_vote"."movie_id" = 1  AND "so1_vote"."rating" = 1 )
>>> # if mov is a mid for a movie
>>> # get movie instance by using Movie.objects.get(mid=mov)
>>> # or query:
>>> # votes = Vote.objects.filter(user__uid__in=uids, movie__mid=mov, rating=1)
>>> likes_count = votes.count()
>>> print likes_count
0

combined:

likes_count = Votes.objects.filter(user__uid__in=uids, movie=mov, rating=1).count()

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