在Django rest框架中，如何在follower和following系统中获取用户名和id？

# models.py
from django.db import models
from django.contrib.auth.models import User

class Follower(models.Model):
    user = models.ForeignKey(User, on_delete=models.CASCADE, related_name='followers')

class Following(models.Model):
    user = models.ForeignKey(User, on_delete=models.CASCADE, related_name='following')

# serializers.py
from rest_framework import serializers
from django.contrib.auth.models import User

class UserSerializer(serializers.ModelSerializer):
    class Meta:
        model = User
        fields = ['id', 'username']

class FollowerSerializer(serializers.ModelSerializer):
    user = UserSerializer()

    class Meta:
        model = Follower
        fields = ['user']

class FollowingSerializer(serializers.ModelSerializer):
    user = UserSerializer()

    class Meta:
        model = Following
        fields = ['user']

# views.py
from rest_framework.views import APIView
from rest_framework.response import Response
from .serializers import FollowerSerializer, FollowingSerializer

class FollowerView(APIView):
    def get(self, request):
        followers = Follower.objects.all()
        serializer = FollowerSerializer(followers, many=True)
        return Response(serializer.data)

class FollowingView(APIView):
    def get(self, request):
        followings = Following.objects.all()
        serializer = FollowingSerializer(followings, many=True)
        return Response(serializer.data)

# urls.py
from django.urls import path
from .views import FollowerView, FollowingView

urlpatterns = [
    path('followers/', FollowerView.as_view(), name='followers'),
    path('followings/', FollowingView.as_view(), name='followings'),
]