instance-based events

[fcurella]

It would be useful if subscribers could receive events only related to a specific instance.

Scenario:

A web application lets users create their own AddressBook. Each AddressBook have many Contacts:

class AddressBook(models.Model):
    user = models.ForeignKey('auth.User')

@webhook_model(
    on_create=ModelEvent('contact.created'),
)
class Contact(models.Model):
    name = models.CharField(max_length=255)
    address_book = models.ForeignKey(AddressBook, related_name='contacts')

There doesn't seem to be a way for a subscriber to receive contact.created events only for Contacts of a specific AddressBook.

[fcurella]

just found about sender_field. Closing.

[ask]

Yeah, the sender_field should work here when you are mapping to a user, possible that it even works for objects that are not users also.

In my first webhook library written a long time ago, the subscribers could match arbitrary fields on the model: https://github.com/ask/durian
This makes for some pretty expensive queries, but maybe it could be extended in Thorn also.

Maybe the event name could have formats so that (if AddressBook here had a name, and a user can have multiple address books (Work, Friends):

@webhook_model(
    on_create=ModelEvent('contact.created.{.address_book.name}'),
    sender_field="address_book.user",
)

Then you could subscribe to contact.created.*, contact.created.Friends, etc.

[fcurella]

@ask, I've wrote an initial implementation for instance-based event name formatting in #8