content_type表將app名稱與其中的表的關係進行儲存

models.py

class Test1(models.Model):
    name = models.CharField(max_length=100)
    #反向查詢
    price = GenericRelation('Test3')

class Test2(models.Model):
    name = models.CharField(max_length=100)
    price = GenericRelation('Test3')

class Test3(models.Model):
    price = models.CharField(max_length=100)
    contex_type = models.ForeignKey(ContentType,on_delete=models.CASCADE)
    obj_id = models.IntegerField()
    #幫助contentType操作
    contex_tobj = GenericForeignKey('contex_type','obj_id')

views.py

obj = Test1.objects.get(id=1)
Test3.objects.create(price=10,contex_tobj=obj)