什么是content type：django内置的一个组件，这个组件帮忙做连表的操作。（混搭连表）
适用场景：适用于一张表与多张表同时做关联的时候。直接导入就可以使用了。
关联数据库说有的表；让我们可以快速插入数据，并且用反向查找能快速查找到数据。
models.py文件建立表
from django.db import models
# Create your models here.
from django.contrib.contenttypes.fields import GenericForeignKey,GenericRelation
from django.contrib.contenttypes.models import ContentType
class Course(models.Model):
'''
普通课程
'''
title=models.CharField(max_length=32)
# 仅用于反向查找
price_policy_list=GenericRelation('PricePolicy')
class DegreeCourse(models.Model):
'''
学位课程
'''
title=models.CharField(max_length=32)
# 仅用于反向查找
price_policy_list=GenericRelation('PricePolicy')
class PricePolicy(models.Model):
'''
价钱策略
'''
price = models.IntegerField()
period = models.IntegerField()
content_type=models.ForeignKey(ContentType,verbose_name='关联的表名称')
object_id=models.IntegerField(verbose_name='关联的表中的数据行的ID')
content_object=GenericForeignKey('content_type','object_id')
# 1. 为学位课“Python全栈”添加一个价格策略：一个月 9.9
"""
obj = DegreeCourse.objects.filter(title='Python全栈').first()
# obj.id
cobj = ContentType.objects.filter(model='course').first()
# cobj.id
PricePolicy.objects.create(price='9.9',period='30',content_type_id=cobj.id,object_id=obj.id)
"""views.py文件，进行数据插入和查看
from django.shortcuts import render,HttpResponse
# Create your views here.
from app01 import models
def test(request):
# 1 为学位课python添加一个价格策略：一个月9.9
# obj1=models.DegreeCourse.objects.filter(title='python').first()
# models.PricePolicy.objects.create(price=9.9,period=30,content_object=obj1)
#
# obj1 = models.DegreeCourse.objects.filter(title='python').first()
# models.PricePolicy.objects.create(price=19.9, period=60, content_object=obj2)
#
# obj1 = models.DegreeCourse.objects.filter(title='python').first()
# models.PricePolicy.objects.create(price=29.9, period=90, content_object=obj3)
# # 2 为学位课rest framework添加一个价格策略：一个月9.9
# obj1=models.Course.objects.filter(title='rest framework').first()
# models.PricePolicy.objects.create(price=9.9,period=30,content_object=obj1)
#
# obj2 = models.Course.objects.filter(title='rest framework').first()
# models.PricePolicy.objects.create(price=19.9, period=60, content_object=obj2)
#
# obj3 = models.Course.objects.filter(title='rest framework').first()
# models.PricePolicy.objects.create(price=29.9, period=90, content_object=obj3)
# 3 根据课程的ID获取课程，并获取该课程的所有价格策略
course=models.Course.objects.filter(id=1).first()
price_policys=course.price_policy_list.all()
print(price_policys)
return HttpResponse('ok')
