Django on_save callback

utils.py

import logging

from django.db import models, transaction
from django.db.models.signals import post_save

logger = logging.getLogger(__name__)

def on_save(obj: models.Model, callback):
    """
    Attaches a one-off callback that's triggered after a Django model instance is
    saved.
    """

    dispatch_uid = f"model_on_save_{id(callback)}"

    def receiver(sender, instance, using, **kwargs):
        if instance == obj:
            try:
                # Disconnect early so that any saves inside the callback don't
                # trigger a nasty loop
                post_save.disconnect(
                    receiver, sender=type(obj), dispatch_uid=dispatch_uid
                )
                transaction.on_commit(callback, using=using)
            except Exception:
                logger.exception("on_save callback failed for %s", str(instance))

    post_save.connect(
        receiver,
        sender=type(obj),
        weak=False,
        dispatch_uid=dispatch_uid,
    )