是否有任何函数可以从 django 的反馈模型中计算特定的选择字段？

Question

        class Feedback(models.Model):
        customer_name = models.CharField(max_length=120)
        email = models.EmailField()
        Place = models.CharField(max_length=120)
        Area_Type = models.ForeignKey(Product, on_delete=models.CASCADE)
        Electricity = models.CharField(max_length=3, choices=[('1','Excellent'),('2','Good'),('3','Bad')])
        Water_Supply = models.CharField(max_length=3, choices=[('1', 'Excellent'), ('2', 'Good'), ('3', 'Bad')])
        details = models.TextField()
        Satisfactory_locality = models.BooleanField()
        date = models.DateField(auto_now_add=True)

1. I have created the above model in Django.
2. From this I want to count number of feedback choices that are Excellent for Electricity field.
3. Please also tell about how to view this count.
4. Do ask if any more information required.
5. It is showing unresolved attribute when Feedback.objects is used as shown below

class ClubChartView(TemplateView):
  template_name = 'clubs/chart.html'
  def get_context_data(self, **kwargs):
      context = super().get_context_data()
      context["qs"] = Feedback.objects.all()
      return context

Answer 1

In django models you can add a property method to a model in which you can reference from anywhere. You can do this by putting the @property decorator and then a function.

class Feedback(models.Model):
    customer_name = models.CharField(max_length=120)
    email = models.EmailField()
    Place = models.CharField(max_length=120)
    Area_Type = models.ForeignKey(Product, on_delete=models.CASCADE)
    Electricity = models.CharField(max_length=3, choices=[('1','Excellent'),('2','Good'),('3','Bad')])
    Water_Supply = models.CharField(max_length=3, choices=[('1', 'Excellent'), ('2', 'Good'), ('3', 'Bad')])
    details = models.TextField()
    Satisfactory_locality = models.BooleanField()
    date = models.DateField(auto_now_add=True)

    @property
    def get_feedback_count(self):
        return Feedback.objects.all().filter(Electricity='1').count()

To pass it to the view you can add it to the context in the views.py as count = Feedback.get_feedback_count()

There is a way to get it from the template using with but i forgot right now.

Answer 2

this question already answered here

examples:

>>> Model.objects.count()
42
>>> Model.related_set.count()
102
>>> Model.related_set.filter(blah=42).count()
3