Signals

Signals let you react to model lifecycle events without coupling code to the model itself.

Built-in Signals

Signal	When	Kwargs
pre_save	Before INSERT/UPDATE	sender, instance, created
post_save	After INSERT/UPDATE	sender, instance, created
pre_delete	Before DELETE	sender, instance
post_delete	After DELETE	sender, instance
pre_update	Before bulk .update()	sender, queryset, fields
post_update	After bulk .update()	sender, queryset, updated_count, fields
pre_bulk_delete	Before bulk .delete()	sender, queryset
post_bulk_delete	After bulk .delete()	sender, queryset, deleted_count

Connecting via Decorator

from ryx import receiver, post_save, post_delete

@receiver(post_save, sender=Post)
async def on_post_saved(sender, instance, created, **kwargs):
    if created:
        await send_notification(f"New post: {instance.title}")
    else:
        await invalidate_cache(f"post:{instance.pk}")

@receiver(post_delete, sender=Post)
async def on_post_deleted(sender, instance, **kwargs):
    await cleanup_files(instance.pk)

Connecting via Method

async def log_change(sender, instance, **kwargs):
    await audit_log.log(f"{sender.__name__} #{instance.pk} changed")

post_save.connect(log_change, sender=Post, weak=False)

tip

Use weak=False for long-lived receivers. Weak references are garbage-collected if nothing else holds a reference.

Disconnecting

post_save.disconnect(on_post_saved, sender=Post)

Custom Signals

from ryx import Signal

post_published = Signal("post_published")

@receiver(post_published, sender=Post)
async def notify_subscribers(sender, instance, **kwargs):
    subscribers = await get_subscribers(instance.author_id)
    for sub in subscribers:
        await send_email(sub.email, f"New post: {instance.title}")

# Fire the signal
await post_published.send(sender=Post, instance=post)

Concurrent Execution

Signal handlers run concurrently via asyncio.gather. If one handler raises, others still execute.

Next Steps

→ Hooks — Per-instance lifecycle methods