[英]How to filter the ManyToMany of a queryset in django
我有兩個模型,問題和他們的答案,我想獲取所有問題以及對它們的單一答案,即,該問題的投票者人數最多的答案。 我如何在查詢集中獲取這個結果(我將對結果進行分頁,以便使用查詢集可以簡化這個過程)
class Question(models.Model):
question = models.CharField(max_length = 128)
asker = models.ForeignKey(CustomUser, on_delete = models.CASCADE, related_name="asked_questions")
requested = models.ManyToManyField(CustomUser, related_name="answer_requests")
followers = models.ManyToManyField(CustomUser, related_name="followed_questions")
topics = models.ManyToManyField(Topic, related_name="questions")
url = models.CharField(max_length = 150)
created_at = models.DateTimeField(auto_now_add = True, blank = True)
def __str__(self):
return self.question
class Answer(models.Model):
answer = models.TextField()
author = models.ForeignKey(CustomUser, on_delete = models.CASCADE, related_name="written_answers")
question = models.ForeignKey(Question, on_delete = models.CASCADE, related_name="answers")
upvoters = models.ManyToManyField(CustomUser, related_name="upvoted_answers")
created_at = models.DateTimeField(auto_now_add = True, blank = True)
from django.db.models import Count, Subquery, OuterRef
answer_subquery = Answer.objects.filter(question=OuterRef('pk')).annotate(upvotes=Count('upvoters')).order_by('-upvotes')
questions = Question.objects.annotate(answer=Subquery(answer_subquery.values('answer')[:1]))
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