ContentType

　　一般我們有多張表同時外來鍵關聯同一張表的時候，可以考慮使用ContentType

models.py

 1 from django.db import models
 2 from django.contrib.contenttypes.models import ContentType # django自己生成的表，裡面儲存著每一個app和它下面的表關係
 3 from django.contrib.contenttypes.fields import GenericForeignKey, GenericRelation
 4 
 5 
 6 class
 
 PythonBasic(models.Model):
 7     course_name = models.CharField(max_length=32)
 8     coupons = GenericRelation(to='Coupon') ##相當於foreignkey
 9 
10 
11 class Oop(models.Model):
12     course_name = models.CharField(max_length=32)
13     coupons = GenericRelation(to='Coupon') ##相當於foreignkey
14 
15 
16
 
 class Coupon(models.Model):
17     coupon_name = models.CharField(max_length=32)
18     content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE) ##
19     object_id = models.PositiveIntegerField() ##
20 
21     content_object = GenericForeignKey("content_type", "object_id") ## 在表中不會真的生成這個欄位，但是對應關係是靠它實現的

views.py

 1 class ContentTypeView(View):
 2 
 3     def get(self, request):
 4         # 獲取表名
 5         # pb = ContentType.objects.filter(app_label='app01', model='pythonbasic').first()
 6         # print(pb.model_class()) # <class 'app01.models.PythonBasic'>
 7         # print(pb.model_class().objects.all()) # <QuerySet [<PythonBasic: PythonBasic object (1)>, <PythonBasic: PythonBasic object (2)>, <PythonBasic: PythonBasic object (3)>]>
 8 
 9         # obj = PythonBasic.objects.get(id=3)
10         obj = Oop.objects.get(id=2)
11         # Coupon.objects.create(coupon_name="Python基礎通關", content_object=obj)
12         print(obj.coupons.all())
13 
14         return HttpResponse('ok')