如何使用Django Rest框架反序列化嵌套对象 [英] How to deserialize nested objects with Django Rest Framework

问题描述

说我有这样的Django模型：

  class Book（models.Model）：
 title = models .CharField（max_length = 150）
 author = models.CharField（max_length = 150）
 
 class Chapter（models.Model）：
 book = models.ForeignKey（Book，related_name ='chapters'）
 title = models.CharField（max_length = 150）
 page_num = models.IntegerField（）
  

和Django Rest框架类：

  class ChapterSerializer（serializers.ModelSerializer）：
 class Meta：
 model = Chapter 
 fields =（'id'，'title'，'page_num'）
 
 class BookSerializer（serializers.ModelSerializer）：
 chapters = ChapterSerializer（many = True）
 
 class Meta：
 model = Book 
 fields =（'id'，'title'，'author' ）
 
 def create（validated_data）：
 chapters = validated_data.pop（'chapters'）
 book = Book（** valida ted_data）
 book.save（）
 serializer = ChapterSerializer（data = chapters，many = True）
如果serializer.is_valid（raise_exception = True）：
 chapters = serializer.save （）
 
 class BookCreate（generics.CreateAPIView）：
 serializer = BookSerializer（data = request.data）
如果serializer.is_valid（raise_exception = True）：
 serializer.save（）
＃做一些其他的东西
  

：

  {
标题：测试书，
作者：测试作者，
章：[
 {标题：测试第1章，page_num：1}，
 {标题：测试第2章，page_num：5} 
] 
} 
  

我收到一个例外，因为章有一个书与它相关联。如果我将 book 添加为 ChapterSerializer 的字段之一，则JSON将无法验证，因为 BookSerializer 在 BookCreate 中将不会验证，因为它将期望这些章节的书籍ID，但该书尚未创建。如何解决这种情况？

有没有办法让 BookSerializer 验证自己的字段，而不是验证其章节？

解决方案

您可以在<$ c上传递其他参数 $ C> .save 。所以我想你只需要将新创建的书实例传递给 serializer ，例如

  def create（validated_data）：
 chapters = validated_data.pop（'chapters'）
 book = Book（** validated_data）
 book.save（）
 serializer = ChapterSerializer（data = chapters，many = True）
如果serializer.is_valid（raise_exception = True）：
 chapters = serializer.save（book = book）
  

Say I have Django models like this:

class Book(models.Model):
  title = models.CharField(max_length=150)
  author = models.CharField(max_length=150) 

class Chapter(models.Model):
  book = models.ForeignKey(Book, related_name='chapters')
  title = models.CharField(max_length=150)
  page_num = models.IntegerField()

and Django Rest Framework classes like this:

class ChapterSerializer(serializers.ModelSerializer):
  class Meta:
    model = Chapter
    fields = ('id', 'title', 'page_num')

class BookSerializer(serializers.ModelSerializer):
  chapters = ChapterSerializer(many=True)

  class Meta:
    model = Book
    fields = ('id', 'title', 'author', 'chapters')

  def create(validated_data):
    chapters = validated_data.pop('chapters')
    book = Book(**validated_data)
    book.save()
    serializer = ChapterSerializer(data=chapters, many=True)
    if serializer.is_valid(raise_exception=True):
        chapters = serializer.save()

class BookCreate(generics.CreateAPIView):
  serializer = BookSerializer(data=request.data)
  if serializer.is_valid(raise_exception=True):
    serializer.save()
  # Do some other stuff

and I POST some JSON like this:

{
  title: "Test book",
  author: "Test author",
  chapters: [
    {title: "Test chapter 1", page_num: 1},
    {title: "Test chapter 2", page_num: 5}
  ]
}

I get an exception because chapter doesn't have a book associated with it. If I add book as one of the fields of ChapterSerializer, then the JSON will fail to validate because the BookSerializer in BookCreate won't validate because it will expect a book id for the chapters, but the book hasn't been created yet. How do I resolve this situation?

Is there a way to have the BookSerializer to validate its own fields and not to validate its chapter's?

解决方案

You can pass additional arguments on .save. So I think you just need to pass the newly created book instance to the serializer, e.g.

def create(validated_data):
    chapters = validated_data.pop('chapters')
    book = Book(**validated_data)
    book.save()
    serializer = ChapterSerializer(data=chapters, many=True)
    if serializer.is_valid(raise_exception=True):
        chapters = serializer.save(book=book)

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