DRF之序列化

• 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": ", ]>"
      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": ", ]>"
  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)