drf 需求案例1

案例：

实现过程：

　　1. 创建一个项目：　　

django-adim  startproject dfr3

　　2.  创建 一个app    homwork  

python manage.py startapp homework

　　3. settings.py    

必须注册 rest_framework 

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'rest_framework',
    'homework',
]

连接数据库：

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'book',
        'HOST':'127.0.0.1',
        'PORT':3306,
        'USER':'root',
        'PASSWORD':'123'
    }
}

主应用  _init_.py 文件下：

import pymysql

pymysql.install_as_MySQLdb()

serilazers.py 文件中

from rest_framework import serializers

from homework.models import Province


class ProvinceModelSerilazers(serializers.ModelSerializer):

    class Meta:
        model = Province
        fields ='__all__'

# 序列化器 2 只显示 id 和name 字段
class Province2ModelSerilazers(serializers.ModelSerializer):

    class Meta:
        model = Province
        fields =['id','name']

views.py

from rest_framework.decorators import action
from rest_framework.response import Response
from rest_framework.viewsets import ModelViewSet,ReadOnlyModelViewSet

from .serilazers import ProvinceModelSerilazers,Province2ModelSerilazers
from .models import Province

class ProvinceModelViewSet(ModelViewSet):

    queryset = Province.objects.all()
    serializer_class = ProvinceModelSerilazers

    @action(methods=['get',],detail=False)
    def get_gdp_top3(self,request):
        '''查gdp前3的省份'''
        # datas= Province.objects.all().order_by('-gdp')[:3]
        # serializer = ProvinceModelSerilazers(instance=datas,many=True)
        datas =self.get_queryset().order_by('-gdp')[:3]
        serializer = self.get_serializer(instance=datas,many=True)
        return Response(serializer.data)

class ProvinceReadOnlyModelViewSet(ReadOnlyModelViewSet):

    queryset = Province.objects.all()
    # serializer_class = ProvinceModelSerilazers

    def get_serializer_class(self):

        if self.action=='list':

            return Province2ModelSerilazers # 当获取所有页只返回两个字段
        else:
            return ProvinceModelSerilazers # 当获取详情页是返回所有字段

路由

1. homework 视图中 urls.py 路由

from django.urls import path,re_path

from rest_framework.routers import DefaultRouter
from homework import views
urlpatterns=[]


router = DefaultRouter()
router.register('province',views.ProvinceModelViewSet)
router.register('prov',views.ProvinceReadOnlyModelViewSet)


urlpatterns += router.urls

2、总路由

from django.contrib import admin
from django.urls import path,include

urlpatterns = [
    path('admin/', admin.site.urls),
    path('hw/', include('homework.urls')),
]