django中的ContentType使用

#比如有专题课，学位课，等其他课程，都有价格，怎么把价格都弄在一张表上

models.py

from django.db import models
from django.contrib.contenttypes.models import ContentType

from django.contrib.contenttypes.fields import GenericForeignKey, GenericRelation


class DegreeCourse(models.Model):
    """学位课程"""
    name = models.CharField(max_length=128, unique=True)
    course_img = models.CharField(max_length=255, verbose_name="缩略图")
    brief = models.TextField(verbose_name="学位课程简介", )


class Course(models.Model):
    """专题课程"""
    name = models.CharField(max_length=128, unique=True)
    course_img = models.CharField(max_length=255)

    #***** 不会在数据库生成列，只用于帮助你进行查询
    policy_list = GenericRelation("PricePolicy")


class PricePolicy(models.Model):
    """价格与有课程效期表"""
    #*****这两个字段名不能变
    content_type = models.ForeignKey(ContentType)  # 关联course or degree_course
    object_id = models.PositiveIntegerField()

    #*****不会在数据库生成列，只用于帮助你进行添加和查询
    content_object = GenericForeignKey('content_type', 'object_id')


    valid_period_choices = (
        (1, '1天'),
        (3, '3天'),
        (7, '1周'), (14, '2周'),
        (30, '1个月'),
        (60, '2个月'),
        (90, '3个月'),
        (180, '6个月'), (210, '12个月'),
        (540, '18个月'), (720, '24个月'),
    )
    valid_period = models.SmallIntegerField(choices=valid_period_choices)
    price = models.FloatField()

views.py

from django.shortcuts import render,HttpResponse
from app01 import models
from django.contrib.contenttypes.models import ContentType

#比如有专题课，学位课，等其他课程，都有价格策略，怎么把价格都弄在一张表上
#在价格策略表添加
#这两个字段名不能变
    #content_type = models.ForeignKey(ContentType)  # 关联ContentType表中的course 或者 degree_course或者其他
    #object_id = models.PositiveIntegerField()

    #不会在数据库生成列，只用于帮助你进行添加和查询
    #content_object = GenericForeignKey('content_type', 'object_id')

def test(request):
    # 1.在价格策略表中添加一条数据，不加content_object = GenericForeignKey('content_type', 'object_id')
    # models.PricePolicy.objects.create(
    #     valid_period=7,
    #     price=6.6,
    #     content_type=ContentType.objects.get(model='course'),
    #     object_id=1
    # )
    #2.加content_object = GenericForeignKey('content_type', 'object_id')后
     # GenericForeignKey这个字段会帮我们自动添加
    # models.PricePolicy.objects.create(
    #     valid_period=14,
    #     price=9.9,
    #     content_object=models.Course.objects.get(id=1)
    # )

    # 2. 根据某个价格策略对象，找到他对应的表和数据，如：管理课程名称
    # price = models.PricePolicy.objects.get(id=2)
    # print(price.content_object.name) # 自动帮你找到

    # 3.找到某个课程关联的所有价格策略 用GenericRelation
    # obj = models.Course.objects.get(id=1)
    # for item in obj.policy_list.all():
    #     print(item.id,item.valid_period,item.price)
    #
    return HttpResponse('...')

urls.py

from django.conf.urls import url
from django.contrib import admin
from app01 import views

urlpatterns = [
    url(r'^admin/', admin.site.urls),
    url(r'^test/', views.test),
]