1 class TestView(APIView):
 2     def get(self, request):
 3         # 找到表id以及表对象
 4         # content_type_obj = ContentType.objects.filter(app_label="Demo", model="food").first()
 5         # print(type(content_type_obj))
 6         # model_class = content_type_obj.model_class()
 7         # print(model_class)
 8         # print(content_type_obj.id)
 9         # 给酱香饼创建优惠券
10         # food_obj = Food.objects.filter(id=1).first()
11         # Coupon.objects.create(title="酱香饼买一送王鸥", content_object=food_obj)
12         # 给黑美人加优惠券
13         # fruit_obj = Fruit.objects.get(id=2)
14         # Coupon.objects.create(title="黑美人2折", content_type_id=9, object_id=2)
15         # Coupon.objects.create(title='鸡蛋饼买一送er',content_type_id=8,object_id=2)
16         # 查询优惠券绑定对象
17         # coupon_obj = Coupon.objects.filter(id=8).first()
18         # print(coupon_obj.content_object.name)
19         # 查某个对象的优惠券
20         food_obj = Food.objects.filter(id=1).first()
21         print(food_obj.coupons.all())
22         
23         # food_obj = Fruit.objects.filter(id=2).first()
24         coupon_obj = food_obj.coupons.all()
25         for coupon in coupon_obj:
26             print(coupon.title)
27         return HttpResponse("ok")

from django.db import models
from django.contrib.contenttypes.models import ContentType
from django.contrib.contenttypes.fields import GenericForeignKey, GenericRelation


# Create your models here.


class Food(models.Model):
    """
    id    name
    1     酱香饼
    2     鸡蛋饼
    3     水煎包
    """
    name = models.CharField(max_length=32)
    # 不生成字段只用于反向查询
    coupons = GenericRelation(to="Coupon")


class Fruit(models.Model):
    """
    id    name
    1     红心蜜柚
    2     黑美人西瓜
    """
    name = models.CharField(max_length=32)
    coupons = GenericRelation(to="Coupon")


class Coupon(models.Model):
    """
    id    title           food_id   fruit_id  ..........
    1     酱香饼买一送一     1        null
    2     黑美人西瓜2折      null     2

    id    title            table_id   object_id
    1     酱香饼买一送一      1            1
    2     黑美人西瓜2折       2           2

    """
    title = models.CharField(max_length=32)
    # 第一版设计
    # food = models.ForeignKey(to="Food")
    # fruit = models.ForeignKey(to="Fruit")
    # 第二版设计
    # table = models.ForeignKey(to="MyTables")
    # object_id = models.IntegerField()
    # 第三版 用django自带的ContentType表
    content_type = models.ForeignKey(to=ContentType)
    object_id = models.IntegerField()
    # 不会生成字段 只用于关联到对象的
    content_object = GenericForeignKey("content_type", "object_id")

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