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")

来源：https://stackoverflow.com/questions/5472818/working-with-djangos-post-save-signal

标签

python

django-signals