问题描述
|
我正在编写类似于Stackoverflow的webapp。我如何查询问题并用分数来注释每个问题,分数就是它拥有多少赞成票减去其拥有多少赞成票。
class Question(models.Model):
pass
class Answer(models.Model):
pass
Vote_CHOICES = (
(\'U\',\'Up\'),(\'D\',\'Down\'),)
class Vote(models.Model):
user = models.ForeignKey(User)
answer = models.ForeignKey(Answer)
type = models.CharField(max_length=1,choices=Vote_CHOICES,db_index=True)
class Meta:
unique_together = ((\"user\",\"answer\"),)
解决方法
VOTE_CHOICES = (
(1,\'Up\'),(-1,\'Down\'),)
将使它变得更加容易:
# q - your question
Vote.objects.filter(answer__question=q).aggregate(Sum(\'type\'))
# all questions annotated
Vote.objects.values(\'answer__question_id\').annotate(score=Sum(\'type\')).order_by()
,尽管DrTyrsa的回答是100%正确的。如果确实需要VOTE_CHOICES为\'U \'和\'D \',则可以在下面使用。
votes = Vote.objects.filter(answer__question=q)
rank = votes.filter(type=\'U\').count() - votes.filter(type=\'D\').count()