Working with Django's post_save() signal

问题:

I have two tables:

class Advertisement(models.Model):     created_at = models.DateTimeField(auto_now_add=True)     author_email = models.EmailField()  class Verification(models.Model):     advertisement = models.ForeignKeyField(Advertisement)     key = models.CharField(max_length=32) 

And I need to auto populate Verification table after adding new advertisement.

def gen_key(sender, instance, created, **kwargs):     if created:         from hashlib import md5         vkey = md5("%s%s" % (instance.author_email, instance.created_at))         ver = Verification(advertisement=instance)         ver.key = vkey         ver.save()  post_save.connect(gen_key, sender=Advertisement) 

Of course it doesn't work. Django 1.2 Q: How should I do it?

---

Ok, halfly solved.
The problem is that post_save() for parent model doesn't calling for childs models.
So you can solve it by providing child class directly.

class Advertisement(models.Model):     created_at = models.DateTimeField(auto_now_add=True)     author_email = models.EmailField()  class Sale(Advertisement):     rooms = models.IntegerField(max_length=1)     subway = models.ForeignKey(Subway)  class Verification(models.Model):     advertisement = models.ForeignKeyField(Advertisement)     key = models.CharField(max_length=32)  def gen_key(sender, instance, created, **kwargs):     code goes here post_save.connect(gen_key, sender=Sale, dispatch_uid="my_unique_identifier") 

So next question is "How can I use parent class for post_save()?"

回答1:

instead of connecting to a specific sender, just connect to post_save in general and check the class of the saved instance in your handler eg

def gen_key(sender, **kwargs):     if issubclass(sender, Advertisement):         code goes here post_save.connect(gen_key, dispatch_uid="my_unique_identifier") 

文章来源: Working with Django's post_save() signal