如何让Django信号调用模型方法？

Question

也许现在已经很晚了,但我无法弄清楚为什么这不起作用.当我有一个post_save信号调用泛型函数时,它可以工作,但是当我有一个post_save信号从模型中调用一个方法时,没有任何反应.这是有效的代码:

class Revision(models.Model):
    # Model junk...

def send_email(sender, instance, created, **kwargs):
    if created:
        print "DO STUFF"

signals.post_save.connect(send_email, sender=Revision)

但这不起作用:

class Revision(models.Model):
    # Model junk...

    def send_email(sender, instance, created, **kwargs):
        if created:
            print "DO STUFF"

signals.post_save.connect(Revision.send_email, sender=Revision)

那里有一个善良的灵魂会阻止我把头砸到墙上吗？谢谢.

Answer 1

在我看来,第二个问题是你使用的是无界方法send_mail.如果你真的想send_mail在课堂上打电话,也许@classmethod或者@staticmethod会帮助你:

class Revision(models.Model):
    # Model junk...

    @classmethod
    def send_email(cls, sender, instance, created, **kwargs):
        if created:
            print "DO STUFF"

signals.post_save.connect(Revision.send_email, sender=Revision)

要么

class Revision(models.Model):
    # Model junk...

    @staticmethod
    def send_email(sender, instance, created, **kwargs):
        if created:
            print "DO STUFF"

signals.post_save.connect(Revision.send_email, sender=Revision)

或者,不使用这些装饰器,您可以传递有界实例方法:

class Revision(models.Model):
# Model junk...

    def send_email(self, sender, instance, created, **kwargs):
        if created:
            print "DO STUFF"

signals.post_save.connect(Revision().send_email, sender=Revision)

参考文献:

1. 从Django 源代码:

   def connect(self, receiver, sender=None, weak=True, dispatch_uid=None):
       """
       Connect receiver to sender for signal.
   
       Arguments:
   
           receiver
               A function or an instance method which is to receive signals.
               Receivers must be hashable objects.
   
               If weak is True, then receiver must be weak-referencable (more
               precisely saferef.safeRef() must be able to create a reference
               to the receiver).
   
               Receivers must be able to accept keyword arguments.
   
               If receivers have a dispatch_uid attribute, the receiver will
               not be added if another receiver already exists with that
               dispatch_uid.
   

2. @classmethod和之间的区别@staticmethod:@staticmethod和@classmethod在Python中有什么区别？