在Django中,当孩子保存在外键关系中时,如何通知父母？

我有以下两种型号:

class Activity(models.Model):
    name = models.CharField(max_length=50, help_text='Some help.')
    entity = models.ForeignKey(CancellationEntity)
    ...


class Cancellation(models.Model):
    activity = models.ForeignKey(Activity)
    date = models.DateField(default=datetime.now().date())
    description = models.CharField(max_length=250)
    ...

我希望活动模型在保存与插入或更新相关的取消时都要注意.

最好的方法是什么？

您想要了解的是Django的信号(也请查看此页面),特别是模型信号 - 更具体地说,是post_save信号.信号是Django的插件/钩子系统版本.每次保存模型时都会发送post_save信号,无论是更新还是创建(并且它会让您知道它是否已创建).这是您在活动取消时使用信号获取通知的方式

from django.db.models.signals import post_save

class Activity(models.Model):
    name = models.CharField(max_length=50, help_text='Some help.')
    entity = models.ForeignKey(CancellationEntity)

    @classmethod
    def cancellation_occurred (sender, instance, created, raw):
        # grab the current instance of Activity
        self = instance.activity_set.all()[0]
        # do something
    ...


class Cancellation(models.Model):
    activity = models.ForeignKey(Activity)
    date = models.DateField(default=datetime.now().date())
    description = models.CharField(max_length=250)
    ...

post_save.connect(Activity.cancellation_occurred, sender=Cancellation)