Django Rest框架我不能使用具有外键的序列化程序保存模型

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

class AuthorSerializer(serializers.ModelSerializer):
    class Meta:
        model = Author
        fields = '__all__'

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

    class Meta:
        model = Book
        fields = '__all__'

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

from rest_framework.decorators import api_view
from rest_framework.response import Response

@api_view(['POST'])
def create_book(request):
    serializer = BookSerializer(data=request.data)
    if serializer.is_valid():
        serializer.save()
        return Response(serializer.data, status=201)
    return Response(serializer.errors, status=400)