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Python 如何使用Django检索模型字段的值分布?_Python_Django_Django Queryset - Fatal编程技术网

Python 如何使用Django检索模型字段的值分布?

Python 如何使用Django检索模型字段的值分布?,python,django,django-queryset,Python,Django,Django Queryset,我有一个这样的模型: class Question(models.Model): #something class Answer(models.Model): question = models.ForeignKey(Question) points_achieved = models.PositiveSmallIntegerField() 现在我想查询得到的分数分布情况:对于每个问题,我想知道有多少人得了0分,1分,等等。 在python中,我将按如下方式执行此操作

我有一个这样的模型:

class Question(models.Model):
  #something

class Answer(models.Model):
  question = models.ForeignKey(Question)      
  points_achieved = models.PositiveSmallIntegerField()
现在我想查询得到的分数分布情况:对于每个问题,我想知道有多少人得了0分,1分,等等。 在python中,我将按如下方式执行此操作:

dists = []
  for q in Question.objects.all():
    dist = defaultdict(int)
    for answer in q.answer_set.all():
      dist[answer.points_achieved]+=1
    dists.append(dist)
如何使用Django的查询方法实现同样的功能?

试试这个

from django.db.models import Count
Answer.objects.all().values('question', 'points_achieved').annotate(total=Count('points_achieved')).order_by('total')

来源:

经过一些疯狂的猜测和下面的教程,我终于想出了这个解决方案:

Answer.objects.values('question','points_achieved')
  .annotate(Count('points_achieved'))
谢谢,刚刚找到了(几乎)相同的解决方案:-)