一、restframework 序列化组件之 serializers

from rest_framework import serializers
from rest_framework.response import Response
from rest_framework.views import APIView

from app01.models import Book


class BookSerializer(serializers.Serializer): # 【自定义一个序列化类】
    title = serializers.CharField(max_length=32) # 【写哪些字段就序列化哪些】
    price = serializers.DecimalField(max_digits=5, decimal_places=2)
    publish = serializers.CharField(max_length=32)  # 一本书对应一个出版社
    publish_email = serializers.CharField(max_length=32, source='publish.email')  # 一本书对应一个出版社
    publish_city = serializers.CharField(max_length=32, source='publish.city')  # 一本书对应一个出版社

    # authors = serializers.CharField(max_length=32)
    # authors = serializers.CharField(max_length=32,source='authors.all')
    # "authors": "<QuerySet [<Author: 张三>, <Author: 王五>]>"
    authors = serializers.SerializerMethodField()

    def get_authors(self, obj):
        ret = []  # 这个数据类型可根据前端需求自己构建
        for i in obj.authors.all():
            ret.append(i.name)
        return ret


class BookView(APIView):

    def get(self, request):
        book_list = Book.objects.all()
        bs = BookSerializer(book_list, many=True) # 【序列化接口】
        print(bs.data)  # 【有序字典】
        return Response(bs.data)

    def post(self,request): #  请求来了必须先校验有效性，才能存入数据库
        bs =BookSerializer(data=request.data)
        print(request.data)  # 【字典】
        print(bs.is_valid())  # 不符合规范就是False
        if bs.is_valid():  # 【校验】
            Book.objects.create(**request.data) # 【存库】
            return Response(bs.data)  # 【返回结果】
        else:
            return Response(bs.errors) # 【返回错误信息】

这样写非常多,每一个字段都得自己写，所以就引出了ModelSerializer，【见 三】

• 运用 source='*'
• serializermethodfield
• read_only和write_only

二、序列化过程（GET请求）

bs = BookSerializer(book_list,many = True)
bs.data
temp = []
for obj in book_list:
    temp.append({
        'title':obj.title,
        'price':obj.price,
        'publish':obj.publish 【此时，取出来的是个对象，显示的是此对象中__str__方法的返回值】
                                所以，设置外键关联的字段也能序列化出来。
      })
1，另外：加上source，就会找source里面的。可用到外键的关联字段里，点出来一个对象之后再找出对象的属性。
      publish = serializers.CharField(max_length=32,source='publish.email')
2，所以：外键的关联对象的任何字段都可以取出。
      publish_email = serializers.CharField(max_length=32,source='publish.email')
      publish_city = serializers.CharField(max_length=32,source='publish.city')
3，多对多字段这样写会形成这样的数据类型：
      authors = serializers.CharField(max_length=32,source='authors.all')
      "authors": "<QuerySet [<Author: 张三>, <Author: 王五>]>"
4，所以：多对多字段可以这样写：
      authors = serializers,SerializerMethodField()
      def get_authors(self,obj):
          ret = []
          for i in obj.authors.all()
              ret.append(i.name)
          return ret
5，序列化时，看见是SerializerMethodField类，就会执行自定义的get_字段名的方法。即可解决多对多的显示问题
      if 字段SerializerMethodField：
       "authors":get_authors(obj)

三、ModelSerializer 的（get查看）和（post添加）

from rest_framework import serializers
from rest_framework.response import Response
from rest_framework.views import APIView

from app01.models import Book


class BookSerializer(serializers.ModelSerializer):
    publish_name = serializers.CharField(max_length=32, source="publish.name", read_only=True)
    publish_city = serializers.CharField(max_length=32, source='publish.city',read_only=True)
    publish_pk=serializers.CharField(max_length=32,source="publish.pk",read_only=True)

    author_list = serializers.SerializerMethodField(read_only=True)  # 【规定只读】
    def get_author_list(self, obj):
        ret = []  # 这个数据类型可根据前端需求自己构建
        for i in obj.authors.all():
            ret.append({'name':i.name,'pk':i.pk})
        return ret

    publish_info = serializers.SerializerMethodField(read_only=True)
    def get_publish_info(self, obj):
        return {"name": obj.publish.name, "publish_pk": obj.publish.pk,"publish_city":obj.publish.city}

    class Meta:
        model = Book
        # fields = ['title','price']
        fields = '__all__'
        extra_kwargs = {"publish": {"write_only": True}, "authors": {"write_only": True}}#【规定只写】


class BookView(APIView):
    def get(self, request):
        book_list = Book.objects.all()
        bs = BookSerializer(book_list, many=True)
        return Response(bs.data)

    def post(self, request):
        bs = BookSerializer(data=request.data, many=False)
        if bs.is_valid():
            bs.save()  # 【create操作,用ModelSerializer就可直接save】
            return Response(bs.data)
        else:
            return Response(bs.errors)