mooc在线教育网开发流程总结（六）其他核心功能

1、泛型外键

通过content_type,object_id,GenericForeignKey三个字段定义任意外键，ContentType是Django里面自带的所有模型的元表（关键字是app_label和model），

from django.contrib.contenttypes.models import ContentType
from django.contrib.contenttypes.fields import GenericForeignKey
from django.db.models import signals
class UserAction(models.Model):content_type = models.ForeignKey(ContentType)object_id = models.PositiveIntegerField(verbose_name="标识")action = GenericForeignKey('content_type', 'object_id')add_time = models.DateTimeField(auto_now_add=True, verbose_name='添加时间',null=True)def __str__(self):return self.user.username+":"+self.action.namedef save(sender, instance, signal, *args, **kwargs):action = UserAction(action=instance)action.save()signals.post_save.connect(save, sender=UserProfile)