Django 如何从 ManyToManyField 序列化并列出所有

Question

我正在使用 Django 1.9.1 开发移动应用程序后端我实现了关注者模型，现在我想列出用户的所有关注者，但我目前坚持这样做。我也使用 Django Rest 框架。

这是我的 UserProfile 模型

class UserProfile(models.Model):
    # Linking UserProfile to User model.
    user = models.OneToOneField(User)
    city = models.CharField(null=True, max_length=30, blank=True)
    gender = models.CharField(null=True, max_length=10, blank=True) # m for male, f for female
    # TODO: Fix the picture later.
    #  picture = models.ImageField(upload_to='profile_images', blank=True)
    age = models.IntegerField(null=True, blank=True)
    caption = models.CharField(null=True, max_length=40, blank=True)
    following_count = models.IntegerField(default=0)
    follower_count = models.IntegerField(default=0)
    post_count = models.IntegerField(default=0)
    like_count = models.IntegerField(default=0)
    date = models.DateTimeField(default=datetime.now(), blank=True)
    is_protected = models.BooleanField(default=False)
    is_facebook_created_user = models.BooleanField(default=False)
    facebook_id = models.CharField(default='', blank=True, max_length=350)
    picture_url = models.URLField(blank=True, max_length=100, null=True)
    followings = models.ManyToManyField('self', related_name='following', symmetrical=False)
    followers = models.ManyToManyField('self', related_name='follower', symmetrical=False)
    blocking = models.ManyToManyField('self', related_name='block', symmetrical=False)
    blocked_by = models.ManyToManyField('self', related_name='blocked', symmetrical=False)

    def block_user(self,username):
            other = UserProfile.objects.get(user__username=username)
            if not self.is_blocking(username):
                self.blocking.add(other)
                other.blocked_by.add(self)
                return True
            else:
                return False

    def unblock_user(self, username):
            other = UserProfile.objects.get(user__username=username)
            if self.is_blocking(username):
                self.blocking.remove(other)
                other.blocked_by.remove(self)
                return True
            else:
                return False

    def follow_user(self, username):
            other = UserProfile.objects.get(user__username=username)
            if not self.is_following(username):
                self.followings.add(other)
                self.following_count = self.followings.all().count()
                self.save()
                other.followers.add(self)
                other.follower_count = other.followers.all().count()
                other.save()
                return True
            else:
                return False

    def unfollow_user(self, username):
            other = UserProfile.objects.get(user__username=username)
            if self.is_following(username):
                self.followings.remove(other)
                self.following_count = self.followings.all().count()
                self.save()
                other.followers.remove(self)
                other.follower_count = other.followers.all().count()
                other.save()
                return True
            else:
                return False

    def is_blocking(self,username):
        return self.blockings.all().filter(user__username=username).exists()

    def is_blocked_by(self,username):
        return self.blocked_by.all().filter(user__username=username).exists()

    def is_following(self, username):  #returns Bool
        return self.followings.all().filter(user__username=username).exists()

    def is_followed_by(self, username):  #returns Bool
        return self.followers.all().filter(user__username=username).exists()

    def __unicode__(self):
        return self.user.username

    def get_token(self):
        try:
            token = Token.objects.get(user_id=self.user_id)
        except:
            token = 'error'
        return token
    def get_username(self):
        return self.user.username

如您所见，我使用 ManyToManyField 作为关注者。现在我想列出一个用户的关注者，但我不想只列出他们的所有信息，因为这是不必要的。我只想列出他们的用户名，因为不需要完整的信息，这只是一种浪费。

这是我的粉丝视图。

@api_view(['GET'])
def get_followers(request):
    username = request.query_params.get('username', None)
    if username is not None:
        if        UserProfile.objects.all().filter(user__username=username).exists():
            wanted = UserProfile.objects.get(user__username=username)
            followers = wanted.followers.all()
            serializer = FollowerSerializer(followers)
            return JsonResponse(serializer.data)
        else:
            return JsonResponse({"result": "user_does_not_exist"})
    else:
        #TODO: return current user's followers
        return JsonResponse({"result": "provide_username"})

我还为用户的关注者添加了一个序列化程序。

class FollowerSerializer(serializers.ModelSerializer):
    class Meta:
        model = UserProfile
        field = ('followers',)

问题是，它只列出了所有用户信息，没有提供用户名，但它只列出了他们的 ID，我无能为力。

我忘了说我确实考虑过使用 ListAPIView，但我无法通过它获取用户名参数。如果有办法获取参数，我也可以使用 ListAPIView 来获取关注者。

如何解决这个问题并只列出他们的用户名？任何帮助将不胜感激。

Answer 1

我在此 link 中使用了嵌套关系。 Django Rest Framework Nested Relationships

只为用户的用户名添加了一个新的序列化器，并更改了另一个序列化器。

# serializes only usernames of users
class EachUserSerializer(serializers.ModelSerializer):
    username = serializers.CharField(source='user.username')

    class Meta:
        model = UserProfile
        fields = ('username',)

class FollowerSerializer(serializers.ModelSerializer):
    followers = EachUserSerializer(many=True, read_only= True)
    followings = EachUserSerializer(many=True,read_only=True)

    class Meta:
        model = UserProfile
        fields = ('followers','followings')

输出正是我想要的：

{
  "followers": [],
  "followings": [
    {
      "username": "sneijder"
    },
    {
      "username": "drogba"
    }
  ]
}

谢谢你的帮助:)

Answer 2

我想你需要的是嵌套序列化器：

class FollowerSerializer(serializers.ModelSerializer):
    username = serializers.CharField(source='user__username')

    class Meta:
        model = UserProfile
        fields = ('username', )


class FollowerSerializer(serializers.ModelSerializer):
    followers = FollowerSerializer(many=True, read_only=True)

    class Meta:
        model = UserProfile
        fields = ('followers', )

Django 如何从 ManyToManyField 序列化并列出所有

Django How to Serialize from ManyToManyField and List All

python

django

serialization

many-to-many

django-rest-framework