Django中的content_type表

models.py

from django.db import models
from django.contrib.contenttypes.models import ContentType
# Django已处理好的方法，帮忙做链表添加，查询
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"""
    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, '7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 django.contrib.contenttypes.models import ContentType
from app01 import models

# Create your views here.


def test(request):
    # 1.自己写入数据
    # models.PricePolicy.objects.create(
    #     valid_period=7,
    #     price=8.8,
    #     content_type=ContentType.objects.get(model="course"),
    #     object_id=1
    # )
    # 2.在models中添加GenericForeignKey方法，改变不大
    # models.PricePolicy.objects.create(
    #     valid_period=14,
    #     price=9.9,
    #     content_object=models.Course.objects.get(id=1)
    # )
    # 3.有GenericForeignKey方法，查询快捷
    # price = models.PricePolicy.objects.get(id=1)
    # print(price.content_object.name)
    # 4.GenericRelation方法帮助快捷跨表查询
    obj = models.Course.objects.get(id=1)
    for item in obj.policy_list.all():
        print(item.id, item.valid_period, item.price)
    return HttpResponse("ok")