drf序列化与反序列化作业1

1、新建一个django项目，定义一个Car类，有name字符串属性，color整型选择属性(0:银色，1:黑色，2:红色，3:灰色)，price全精度小数类型，image图片文件类型，brand字符串类型

2、基于ModelSerializer类，完成Car资源的单查，群查，单增接口
	序列化：显示车名，车的颜色，车的价格，车的海报，车的品牌
	反序列化：必须提供车名，车的价格，车的品牌(车的匹配需要二次确认re_brand)，车的颜色默认为银色(可以提供)，车的海报不需要提供(默认为空)

代码

#urls

from django.conf.urls import url,include
from django.contrib import admin
from django.conf import settings
from django.views.static import serve


urlpatterns = [
    url(r'^admin/', admin.site.urls),
    url(r'^api/',include('api.urls')),
    url(r'^media/(?P<path>.*)',serve,{'document_root':settings.MEDIA_ROOT})
]

#view
from django.shortcuts import render

# Create your views here.
from rest_framework.views import APIView
from rest_framework.response import Response
from . import models,serializers

class CarAPIView(APIView):
    def get(self,request,*args,**kwargs):
        pk = kwargs.get('pk')
        if pk:
            car_obj = models.Car.objects.filter(pk=pk).first()
            if not car_obj:
                return Response({
                    'status':1,
                    'msg':'pk error'
                })
            car_ser = serializers.CarModelSerializer(car_obj)
            return Response({
                'status':0,
                'msg':'ok',
                'results':car_ser.data
            })

        car_query = models.Car.objects.all()
        car_ser = serializers.CarModelSerializer(car_query,many=True)
        return Response({
            'status':0,
            'msg':'ok',
            'results':car_ser.data
        })

    def post(self,request,*args,**kwargs):
        car_ser = serializers.CarModelSerializer(data=request.data)

        #校验不通过会自动抛出异常，代码不会继续往下执行
        car_ser.is_valid(raise_exception=True)
        car_obj = car_ser.save()
        return Response({
            'status':0,
            'msg':'ok',
            'results':serializers.CarModelSerializer(car_obj).data
        })

#model
from django.db import models

# Create your models here.

class Car(models.Model):
    COLOR_CHOICES = [(0,'银色'),(1,'黑色'),(2,'红色'),(3,'灰色')]
    name = models.CharField(max_length=64)
    colors = models.IntegerField(choices=COLOR_CHOICES,default=0)
    price = models.DecimalField(max_digits=10,decimal_places=2)
    brand = models.CharField(max_length=64)
    image = models.ImageField(upload_to='img',default='img/default.png')

    @property
    def car_color(self):
        return self.get_colors_display()

#serializers
from rest_framework import serializers
from . import models

class CarModelSerializer(serializers.ModelSerializer):
    re_brand = serializers.CharField(write_only=True)
    class Meta:
        model = models.Car
        #指向序列化反序列化的models类
        fields = ['name','price','color','car_color','image','brand','re_brand']
        extra_kwargs = {
            'image':{
                'read_only':True
            },
            'color':{
                'write_only':True
            }
        }

        def validate(self,attrs):
            brand = attrs.get('brand')
            re_brand = attrs.pop('re_brand')
            if brand != re_brand:
                raise serializers.ValidationError({'re_brand':'品牌输入不正确'})
            return attrs