Django-RESTful Api 之序列化

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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

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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

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    # -*- 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

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    python manage.py shell

  • 增加学生

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    >>> 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

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    >>> 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

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    >>>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

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    >>> 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

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    >>> 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

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    >>> 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

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