本文中讨论的好友列表模型设计如下：

user_id = models.ForeignKey(ChatUserInfo, to_field="chat_id", on_delete=models.DO_NOTHING, db_index=True,     help_text="聊天用户id")
friend_id = models.ForeignKey(ChatUserInfo, to_field="chat_id", related_name="friend", on_delete=models.DO_NOTHING, db_index=True, help_text="聊天用户id")
user_group = models.ForeignKey(ChatGroupType, to_field="flag", on_delete=models.CASCADE, help_text="好友分组")
friend_group = models.ForeignKey(ChatGroupType, to_field="flag", related_name="friend_group", on_delete=models.CASCADE, help_text="好友分组")
user_label = models.CharField(max_length=64，help_text="备注信息")
friend_label = models.CharField(max_length=64，help_text="备注信息")
create_time = models.DateTimeField("添加好友时间", auto_now_add=True)
update_time = models.DateTimeField("更新分组时间", auto_now=True)
resource = models.ForeignKey(ChatFriendResource, to_field="origin", on_delete=models.DO_NOTHING, help_text="好友来源")

即A和B互为好友，在数据库中只会保存一条记录，这样节省磁盘空间。

对于这样的模型，当前端需要展示当前用户的好友列表时，序列化方式如下：

views.py:
def get(self, request, *args, **kwargs):
    """
    聊天-好友列表
    :param request:
    :param args:
    :param kwargs:
    :return:
    """
    try:
        chat_id = request.query_params.get("chat_id", "")
        # chat_id = request.user.user.chat_id  # 添加用户认证后再使用request.user
        chat_user = models.ChatUserInfo.objects.get(chat_id=int(chat_id))
    except ValueError:
        return Response(dict(msg="请输入用户id"), status=status.HTTP_400_BAD_REQUEST)
    except models.ChatUserInfo.DoesNotExist:
        return Response(dict(msg="用户不存在"), status=status.HTTP_400_BAD_REQUEST)

    # 好友列表
    user_friends = models.ChatFriendList.objects.filter(Q(user_id=chat_id) | Q(friend_id=chat_id))
    ser = serializer.FriendSerializer(instance=user_friends, many=True, context={"chat_user": chat_user})

    friends = []
    for data in ser.data:
        friend_dict = OrderedDict()
        if data["user_id"] == int(chat_id):
            friend_dict["friend_id"] = data["friend_id"]
            friend_dict["friend_avatar"] = data["friend_avatar"]
        if data["friend_id"] == int(chat_id):
            friend_dict["friend_id"] = data["user_id"]
            friend_dict["friend_avatar"] = data["user_avatar"]
        friend_dict["friend_name"] = data["friend_name"]
        friend_dict["friend_area"] = data["friend_area"]
        friend_dict["friend_status"] = data["friend_status"]
        friend_dict["friend_label"] = data["friend_label"]
        friend_dict["friend_resource"] = data["friend_resource"]
        friends.append(friend_dict)
    logger.debug("data:%s", ser.data)
    return Response(dict(msg="OK", data=friends), status=status.HTTP_200_OK)

serializer.py:
class FriendSerializer(serializers.Serializer):
    """
    序列化-好友列表-好友信息  ChatFriendList
    """
    # 用户id
    # friend_id = serializers.SerializerMethodField(method_name="get_id")
    user_id = serializers.IntegerField(source="user.chat_id")
    friend_id = serializers.IntegerField(source="friend.chat_id")
    # 用户昵称
    friend_name = serializers.SerializerMethodField(method_name="get_name")
    # 用户头像
    # friend_avatar = serializers.SerializerMethodField(method_name="get_avatar")
    user_avatar = serializers.ImageField(source="user.user.avatar")
    friend_avatar = serializers.ImageField(source="friend.user.avatar")
    # 用户地区
    friend_area = serializers.SerializerMethodField(method_name="get_area")
    # 用户状态
    friend_status = serializers.SerializerMethodField(method_name="get_status")
    # 用户备注
    friend_label = serializers.SerializerMethodField(method_name="get_label")
    # 用户来源
    friend_resource = serializers.CharField(source="resource")

    def get_id(self, obj):
        """
        获取好友id
        :param obj:
        :return:
        """
        if obj.user.chat_id == self.context['chat_user'].chat_id:
            # user_id是当前用户
            return obj.friend.chat_id
        return obj.user.chat_id

    def get_name(self, obj):
        """
        获取好友昵称
        :param obj:
        :return:
        """
        if obj.user.chat_id == self.context['chat_user'].chat_id:
            # user_id是当前用户
            return obj.friend.user.nickname
        return obj.user.user.nickname

    def get_avatar(self, obj):
        """
        获取好友头像
        :param obj:
        :return:
        """
        if obj.user.chat_id == self.context['chat_user'].chat_id:
            # user_id是当前用户
            return obj.friend.user.avatar
        return obj.user.user.avatar

    def get_area(self, obj):
        """
        获取好友地区
        :param obj:
        :return:
        """
        if obj.user.chat_id == self.context['chat_user'].chat_id:
            # user_id是当前用户
            return obj.friend.area
        return obj.user.area

    def get_status(self, obj):
        """
        获取好友状态
        :param obj:
        :return:
        """
        if obj.user.chat_id == self.context['chat_user'].chat_id:
            # user_id是当前用户
            return obj.friend.status
        return obj.user.status

    def get_label(self, obj):
        """
        获取好友备注
        :param obj:
        :return:
        """
        if obj.user.chat_id == self.context['chat_user'].chat_id:
            # user_id是当前用户
            return obj.friend_label
        return obj.user_label

    def create(self, validated_data):
        pass

    def update(self, instance, validated_data):
        pass

上面的序列化主要使用了serializers.ImageField 和 serializers.SerializerMethodField，如有错误之处，欢迎交流指正！