如何在DJANGO REST中保存外键值？

from django.db import models

class Author(models.Model):
    name = models.CharField(max_length=100)

class Book(models.Model):
    title = models.CharField(max_length=100)
    author = models.ForeignKey(Author, on_delete=models.CASCADE)

from rest_framework import serializers
from .models import Author, Book

class AuthorSerializer(serializers.ModelSerializer):
    class Meta:
        model = Author
        fields = ['id', 'name']

class BookSerializer(serializers.ModelSerializer):
    author = AuthorSerializer()

    class Meta:
        model = Book
        fields = ['id', 'title', 'author']

    def create(self, validated_data):
        author_data = validated_data.pop('author')
        author, created = Author.objects.get_or_create(**author_data)
        book = Book.objects.create(author=author, **validated_data)
        return book

    def update(self, instance, validated_data):
        author_data = validated_data.pop('author')
        author, created = Author.objects.get_or_create(**author_data)
        instance.author = author
        instance.title = validated_data.get('title', instance.title)
        instance.save()
        return instance

from rest_framework import viewsets
from .models import Book
from .serializers import BookSerializer

class BookViewSet(viewsets.ModelViewSet):
    queryset = Book.objects.all()
    serializer_class = BookSerializer

from django.urls import path, include
from rest_framework.routers import DefaultRouter
from .views import BookViewSet

router = DefaultRouter()
router.register(r'books', BookViewSet)

urlpatterns = [
    path('', include(router.urls)),
]

author, created = Author.objects.get_or_create(name='Author Name')

class BookSerializer(serializers.ModelSerializer):
    author = AuthorSerializer()

    class Meta:
        model = Book
        fields = ['id', 'title', 'author']