from django.db import models

from django.contrib.contenttypes.models import ContentType

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

class Course(models.Model):

    title = models.CharField(max_length=32)

    # 不会在数据库中生成字段，只用于数据库操作

    # policy = GenericRelation('PricePolicy',object_id_field='object_id',content_type_field='contentType')

class DegreeCourse(models.Model):

    title = models.CharField(max_length=32)

class PricePolicy(models.Model):

    # 跟ContentType表做外键关联

    contentType = models.ForeignKey(to=ContentType)

    # 正数

    object_id = models.PositiveIntegerField()

    # 引入一个字段，不会在数据库中创建，只用来做数据库操作

    # content_obj = GenericForeignKey('contentType', 'object_id')

    period = models.CharField(max_length=32)

    price = models.FloatField()

from app01 import models

def test(request):

    import json

    # 方式一插入价格规则

    # ret=models.ContentType.objects.filter(model='course').first()

    # course=models.Course.objects.filter(pk=1).first()

    # print(ret.id)

    # models.PricePolicy.objects.create(period='30',price=100,object_id=course.id,contentType_id=ret.id)

    # 方式二插入价格规则

    # course=models.Course.objects.filter(pk=1).first()

    # # content_obj=course  会自动的把课程id放到object_id上，并且去ContentType表中查询课程表的id，放到contentType上

    # models.PricePolicy.objects.create(period='60',price=800,content_obj=course)

    # 增加学位课，价格规则

    # degreecourse = models.DegreeCourse.objects.filter(pk=1).first()

    # models.PricePolicy.objects.create(period='60', price=800, content_obj=degreecourse)

    # 查询所有价格策略，并且显示对应的课程名称

    # ret=models.PricePolicy.objects.all()

    # for i in ret:

    #     print(i.price)

    #     print(i.period)

    #     # content_obj 就是代指关联的课程，或者学位课程的那个对象

    #     print(type(i.content_obj))

    #     print(i.content_obj.title)

    # 通过课程id，获取课程信息和价格策略

    course=models.Course.objects.filter(pk=1).first()

    print(course.policy.all())