python - django View - 获取 ManyToMany 字段的值

Question

我有一个投票应用程序，其投票模型中有一个 ManytoMany 字段。

我想检索 View 中的 choice(ManyToMany) 字段的值。

models.py

class Poll(models.Model):
    question = models.CharField(max_length=250)
    pub_date = models.DateTimeField()
    end_date = models.DateTimeField(blank=True, null=True)
    choice= models.ManyToManyField(Choice)

def __unicode__(self):
  return smart_unicode(self.question)

class Choice(models.Model):
    name = models.CharField(max_length=50)
    photo = models.ImageField(upload_to="img")
    rating = models.CharField(max_length=10)

def __unicode__(self):
  return smart_unicode(self.name)

views.py每次民意调查中有 2 个选择，我想将每个选择分配给 2 个单独的变量，但不知道如何操作。

def polling(request)
    try:
        choices = Poll.objects.all()
        choice_1 = **assign 1st ManyToMany Field value** 
        choice_2 = **assign 2nd ManyToMany Field value** 

Answer 1

我想是这样的

def polling(request):
    for poll in Poll.objects.all():
        choice_1 = poll.choice.all()[0]
        choice_2 = poll.choice.all()[1]

或

def polling(request):
    for poll in Poll.objects.all():
        for choice in poll.choice.all():
            # Do something with choice

注意:如果每个 poll 对象总是有 2 个选择，您不妨使用外键来代替

class Poll(models.Model):
    question = models.CharField(max_length=250)
    pub_date = models.DateTimeField()
    end_date = models.DateTimeField(blank=True, null=True)
    choice_one = models.ForeignField(Choice)
    choice_two = models.ForeignField(Choice)

这样，就不需要第三个表来跟踪选择和民意调查之间的关系，从而提高效率。

最后，您应该看一下 django 文档，它很好地解释了所有这些:https://docs.djangoproject.com/en/1.7/topics/db/examples/many_to_many/