django：根据对象数计算百分比 [英] django: calculate percentage based on object count

问题描述

我有以下模型：

class Question(models.Model):
    question = models.CharField(max_length=100)

class Option(models.Model):
    question = models.ForeignKey(Question)
    value = models.CharField(max_length=200)

class Answer(models.Model):
    option = models.ForeignKey(Option)

每个问题具有用户定义的选项。例如：问题-最好的水果是什么？选项-苹果，橙，葡萄。现在其他用户可以答案问题，其回答仅限于选项。

Each Question has Options defined by the User. For Example: Question - What is the best fruit? Options - Apple, Orange, Grapes. Now other user's can Answer the question with their responses restricted to Options.

我有以下视图：

def detail(request, question_id):
    q = Question.objects.select_related().get(id=question_id)
    a = Answer.objects.filter(option__question=question_id)
    o = Option.objects.filter(question=question_id).annotate(num_votes=Count('answer'))
    return render(request, 'test.html', {
        'q':q, 
        'a':a,
        'o':o,
    })

对于o中的每个选项，我都会收到一个答案计数。例如：

For each option in o, I am receiving an answer count. For example:

问题-最好的水果是什么？

选项-葡萄，橙，苹果

答案-葡萄：5票，橙色5票，苹果10票。

Question - What is the best fruit?
Option - Grape, Orange, Apple
Answer - Grape: 5votes, Orange 5votes, Apple 10vote.

从该问题的总票数中计算每个选项的投票百分比的最佳方法是什么？

What is the best way to calculate the vote percentage for each option out of the total number of votes for that question?

换句话说，我想要这样的东西：

In other words, I want something like this:

答案-葡萄：5票25％票，橙色5票25％票，苹果10票50％票。

Answer - Grape: 5votes 25%votes, Orange 5votes 25%votes, Apple 10vote 50%votes.

test.html

test.html

{% for opt in o %}
     <tr>
         <td>{{ opt }}</td>
     <td>{{ opt.num_votes }}</td>
     <td>PERCENT GOES hERE</td>
</tr>
 {% endfor %}

 <div>
     {% for key, value in perc_dict.items %}
         {{ value|floatformat:"0" }}%
     {% endfor %}
 </div>

推荐答案

尝试一下

total_count = Answer.objects.filter(option__question=question_id).count()
perc_dict = { }
for o in q.option_set.all():
    cnt = Answer.objects.filter(option=o).count()
    perc = cnt * 100 / total_count
    perc_dict.update( {o.value: perc} )

#after this the perc_dict will have percentages for all options that you can pass to template.

---

更新：向queryset添加属性并不容易，而且用键作为变量引用模板中的字典也是不可能的。

---

Update: Adding attribute to queryset is not easy and referring dicts in templates with key as variable is not possible too.

所以解决方案是在 Option 模型中添加方法/属性，以获取

So the solution would be add method/property in Option model to get percentage as

class Option(models.Model):
    question = models.ForeignKey(Question)
    value = models.CharField(max_length=200)
    def get_percentage(self):
        total_count = Answer.objects.filter(option__question=self.question).count()
        cnt = Answer.objects.filter(option=self).count()
        perc = cnt * 100 / total_count
        return perc

然后，在模板中，您可以使用所有这种方法来获取百分比，如下所示：

Then in template you can all this method to get percentage as

{% for opt in o %}
     <tr>
         <td>{{ opt }}</td>
     <td>{{ opt.num_votes }}</td>
     <td>{{ opt.get_percentage }}</td>
</tr>
 {% endfor %}

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