CODEWITHSUNDEEP
djangotransactionssignalscommit
Grégoire Cachet
Grégoire Cachet

Reputation: 2607

run code after transaction commit in Django

Is there any way to run some code after transaction commit in Django?

I need to send some messages to a rabbitmq server for offline processing, but the message gets to the consumer before the Django transaction is commited.

My message is sent in the post_save signal of the model. What I'm looking for is a similar mechanism, using signals or something else, that would execute code after the commit (and do nothing if the transaction fails).

I haven't found any generic way of doing it in Django. Do you have any ideas?

Upvotes: 28

Views: 20283

Answers (5)

Carl Meyer
Carl Meyer

Reputation: 126721

django-transaction-hooks solves this problem for Django < 1.9, and the functionality is built into Django 1.9+:

from django.db import transaction

def do_something():
    pass  # send a mail, invalidate a cache, fire off a Celery task, etc.

transaction.on_commit(do_something)

Upvotes: 25

Igor Kramaric
Igor Kramaric

Reputation: 173

Hope this may help someone using Django 1.9 or later. Since 1.9 on_commit is available.

So basically you would be doing it like this:

from django.db import transaction

transaction.on_commit(
    lambda: send_msg_to_rabbitmqp(param1, param2, ...)
)

If you wish to keep post_save, you can still use on_commit:

@receiver(pre_save, sender=MyModel)
def my_handler(sender, instance, created, **kwargs):
    transaction.on_commit(
        lambda: send_msg_to_rabbitmqp(instance.id)
    )

Upvotes: 15

bradley.ayers
bradley.ayers

Reputation: 38392

Have a look at django-celery-transactions for a solution to this.

I've recently finished splitting-out and refactoring the underlying signals code code into a stand-alone app django-db-signals.

Upvotes: 1

Gr&#233;goire Cachet
Gr&#233;goire Cachet

Reputation: 2607

I have implemented transaction signals (post_commit and post_rollback) by monkey patching django: http://gist.github.com/247844

Upvotes: 5

Daniel Roseman
Daniel Roseman

Reputation: 600051

One possibility would be to subclass the transaction middleware so that it sends a custom signal on commit. Your code could listen for that signal, rather than post_save.

Upvotes: 1

Related Questions