django - 通过过滤对象列表获取对象列表

Question

我正在创建一个用户活动流。

活动模型：

class Activity(models.Model):
    actor = models.ForeignKey(User)
    action = models.CharField(max_length=100)
    content_type = models.ForeignKey(ContentType)
    object_id = models.PositiveIntegerField()
    content_object = generic.GenericForeignKey('content_type', 'object_id')
    pub_date = models.DateTimeField(auto_now_add=True, auto_now=False)

关系模型：

class Person(models.Model):
    user = models.OneToOneField(User)
    relationships = models.ManyToManyField('self', through='Relationship', 
                                           symmetrical=False, 
                                           related_name='related_to')
RELATIONSHIP_FOLLOWING = 1
RELATIONSHIP_BLOCKED = 2
RELATIONSHIP_STATUSES = (
    (RELATIONSHIP_FOLLOWING, 'Following'),
    (RELATIONSHIP_BLOCKED, 'Blocked'),
)

class Relationship(models.Model):
    from_person = models.ForeignKey(Person, related_name='from_people')
    to_person = models.ForeignKey(Person, related_name='to_people')
    status = models.IntegerField(choices=RELATIONSHIP_STATUSES)  

def get_relationships(self, status):
    return self.relationships.filter(
        to_people__status=status, 
        to_people__from_person=self)

def get_following(self):
    return self.get_relationships(RELATIONSHIP_FOLLOWING)

在视图中：

def home(request):
    if request.user.is_authenticated():
        user = request.user
        userP = Person.objects.get_or_create(user=user)
        userP = userP[0]
        following = userP.get_following()
        activities = Activity.objects.filter(actor__in=following)
        if request.POST:
            form = StatusForm(request.POST, request.FILES)
            if form.is_valid():
                if form.cleaned_data:
                    status = form.save(commit=False)
                    status.user = user
                    status.save()
                    return HttpResponseRedirect('/')

场景

• 用户正在关注用户 2 和用户 3
• user2 正在关注 user 和 user3
• user3 正在关注 user 和 user2

因为我使用actor=user 而不是actor=userP（这是user.person 类型的对象）过滤活动。我如何从get_following() 方法列表中获取user object 列表，而不是user.person object。

但是，我可以像这样循环遍历每个 following：

    following = userP.get_following()
    users = []
    for u in following:
        users.append(u.user)
    users.append(user)
    activities = Activity.objects.filter(actor__in=users)

但我希望有另一种更好的方法来做到这一点？

请指导我。您的帮助将不胜感激。谢谢。

Answer 1

使用查询集的values_list() 方法：

activities = Activity.objects.filter(actor__in=
                                     following.values_list('user', flat=True))

如果您想将另一个用户添加到演员列表，那么您必须将 valies_list 从查询集转换为常规 python 列表：

actors = list(following.values_list('user', flat=True)) + [user.id]
activities = Activity.objects.filter(actor__in=actors)