mysql - 我如何计算 django 中这些条目的平均分数？

Question

所以我有这个模型:

class scoreShow(models.Model):
    dancer = models.ForeignKey(dancer)
    s1 = models.IntegerField(max_length = 2)
    s2 = models.IntegerField(max_length = 2)
    s3 = models.IntegerField(max_length = 2)
    s4 = models.IntegerField(max_length = 2)
    s5 = models.IntegerField(max_length = 2)
    s6 = models.IntegerField(max_length = 2)
    s7 = models.IntegerField(max_length = 2)
    counter = models.IntegerField(max_length = 2)
    stotal = models.IntegerField(max_length = 3)
    field_1 = models.IntegerField(max_length = 20, null=True, blank=True)
    field_2 = models.CharField(max_length = 20, null=True, blank=True)

    def __unicode__(self):
        return str(self.dancer) 

从这个 View 表单中获取的信息:

def scores(request):
     perf = dancer.objects.filter(perform=True)

     if request.method =='POST':
        intpk = request.POST.get("form")
        whendone = request.POST.get("done")

        contestant =dancer.objects.get(pk=intpk)

        showcase = inlineformset_factory(dancer, scoreShow, extra = 1)
        form = showcase(instance=None)

        if whendone == "save":

            form = showcase(request.POST, request.FILES, instance=contestant)
            if form.is_valid():
                form.save()

     return render_to_response("scores.html",locals(), context_instance = RequestContext(request))

它接受大约 13 个人的 1 到 10 的数值。我需要计算 13 个人得分的平均值。2 个平均值:

1. 前 7 个类别的平均值。 s1 的平均值，s2 的平均值 &

2. 将所有 S 加在一起的平均值，即 s1 总数 + s2 总数的平均值...除以条目总数。

如果可能的话，我还想避免让任何人两次提交乐谱。谁能帮我解决这个问题？

Answer 1

1. 您可以使用 Aggregation feature通过调用:

   from django.db.models import Avg
   qs = ScoreShow.objects.all()
   return qs.aggregate(Avg('s1'), Avg('s2'), Avg('s3'), Avg('s4'), Avg('s5'), Avg('s6'),Avg('s7'))
   

   或更短一点:

   qs = ScoreShow.objects.all()
   return qs.aggregate(*[Avg('s%d' % i) for i in range(1, 8)])
   

2. 要一起计算所有分数的平均值，您需要将聚合与 annotate 结合使用:

   from django.db.models import Avg, Sum
   fields = ['s%d' % i for i in range(1,8)]
   qs = ScoreShow.objects.annotate(sAll=Sum('id', field='+'.join(fields))).all()
   return qs.aggregate(Avg('sAll'))
   

3. 为确保没有人提交两个分数，将 unique=True 添加到 dancer 外键:

   class ScoreShow(models.Model):
       dancer = models.ForeignKey(dancer, unique=True)