Django-RESTful Api之序列化

前后端分离

• 前台和后台的开发分离开发，就需要借助API。API就是开发人员提供的编程接口以供他人调用

安装

pip install djangorestframework

构建开发环境

什么是序列化？

• 把模型对象转换为JSON格式然后响应出去，这样便于客户端调用时解析

创建序列化类

• 在应用目录下创建名为serializers.py文件

  # -*- coding:utf-8 -*-
  from rest_framework import serializers
  from myApp.models import Student
  
  
  # 只能序列化Student模型对象
  class StudentSerializer(serializers.ModelSerializer):
      class Meta:
          model = Student
          fields = ("id", "name", "sex", "age", "content", "grade")

使用序列化类

• 进入shell模式

  python manage.py shell

• 增加学生

  >>> from myApp.models import Student, Grade
  >>> grade = Grade.objects.get(pk=1)
  >>> stu = Student.create("liudehua",True,50,"liudehua shuai",grade)
  >>> stu.save()

• 引入序列化类，创建序列化对象查看可序列化的字段

  >>> from myApp.serializers import StudentSerializer
  >>> serializer = StudentSerializer()
  >>> print(serializer)

• 依据学生创建序列化对象，再对对象进行序列化操作

  >>>serializer = StudentSerializer(stu)
  >>> print(serializer.data)
  {'id': 1, 'name': 'liudehua', 'sex': True, 'age': 50, 'contend': 'liudehua shuai', 'grade': 1}
  >>> print(type(serializer.data))
  <class 'rest_framework.utils.serializer_helpers.ReturnDict'>

• 将数据渲染成json格式

  >>> from rest_framework.renderers import  JSONRenderer
  >>> content = JSONRenderer().render(serializer.data)
  >>> print(content)
  b'{"id":1,"name":"liudehua","sex":true,"age":50,"contend":"liudehua shuai","grade":1}'

• 反序列化

  >>> from rest_framework.renderers import  JSONRenderer
  >>> content = JSONRenderer().render(serializer.data)
  >>> print(content)
  b'{"id":1,"name":"liudehua","sex":true,"age":50,"contend":"liudehua shuai","grade":1}'
  >>> from rest_framework.parsers import JSONParser
  >>> from django.utils.six import BytesIO
  >>> stream = BytesIO(content)
  >>> print(stream)
  <_io.BytesIO object at 0x00000181C2588728>
  >>> stu2=JSONParser().parse(stream)
  >>> print(stu2)
  {'id': 1, 'name': 'liudehua', 'sex': True, 'age': 50, 'contend': 'liudehua shuai', 'grade': 1}

  当客户需要修改、增加、删除数据时，就要把过程反过来，就叫做反序列化。

• 检测数据并保存

  >>> stu2.save()
  Traceback (most recent call last):
    File "<console>", line 1, in <module>
  AttributeError: 'dict' object has no attribute 'save'
  >>> serializer = StudentSerializer(data=stu2)
  >>> print(serializer.is_valid())
  True
  >>> print(serializer.validated_data)
  OrderedDict([('name', 'liudehua'), ('sex', True), ('age', 50), ('contend', 'liudehua shuai'), ('grade', <Grade: python01>)])
  >>> serializer.save()
  <Student: liudehua>

视图实现使用序列化

url(r'^students/$', views.studentsList),
url(r'^students/(?P<pk>\d+)', views.studentDetail),

from django.shortcuts import render
from django.http import HttpResponse, JsonResponse
from myApp.models import Student, Grade
from myApp.serializers import StudentSerializer
from rest_framework.parsers import JSONParser
from rest_framework.renderers import JSONRenderer
from django.utils.six import BytesIO


# Create your views here.
def studentsList(request):
    if request.method == "GET":
        stus = Student.objects.all()
        serializer = StudentSerializer(stus, many=True)
        return JsonResponse(serializer.data, safe=False)
    elif request.method == "POST":
        content = JSONRenderer().render(request.POST)
        stream = BytesIO(content)
        data = JSONParser().parse(stream)
        serializer = StudentSerializer(data=data)
        if serializer.is_valid():
            serializer.save()
            return JsonResponse(serializer.data, status=201)
        return JsonResponse(serializer.errors, status=400)


def studentDetail(request, pk):
    try:
        stu = Student.objects.get(pk=pk)
    except Student.DoesNotExist as e:
        return HttpResponse(status=404)
    if request.method == "GET":
        serializer = StudentSerializer(stu)
        return JsonResponse(serializer.data)
    elif request.method == "PUT":
        content = JSONRenderer().render(request.POST)
        stream = BytesIO(content)
        data = JSONParser().parse(stream)
        serializer = StudentSerializer(stu, data=data)
        if serializer.is_valid():
            serializer.save()
            return JsonResponse(serializer.data, status=201)
        return JsonResponse(serializer.errors, status=400)
    elif request.method == "DELETE":
        stu.delete()
        return HttpResponse(status=204)