I've been trying to add stamps to a complex task canvas, but I've found that they don't get stored in the results table with result_extended enabled. I've attempted to trace why this isn't working and it seems that django-celery-results just doesn't retrieve stamp data.

In celery.backends.base.Base, there is a _get_result_meta() method, which builds extended metadata if extended results are enabled. Among other things on L494 this retrieves stamps and assigns them to the meta object.

In django-celery-results, collecting extended result data is instead performed in the django_celery_results.backends.database.DatabaseBackend by the _get_extended_properties() method, which doesn't do anything to stamps. The _get_meta_from_request() method retrieves metadata from the request, but there's nothing to actually put stamps into the metadata.

I've been able to fix this in my project by subclassing DatabaseBackend and overriding _get_meta_from_request():

from celery.backends.base import get_current_task
from django_celery_results.backends.database import DatabaseBackend as _DatabaseBackend

class DatabaseBackend(_DatabaseBackend):
    def _get_meta_from_request(self, request=None):
        meta = super()._get_meta_from_request(request)
        request = request or getattr(get_current_task(), "request", None)

        if getattr(request, 'stamps', None):
            meta["stamped_headers"] = request.stamped_headers
            meta.update(request.stamps)

        return meta

It seems the cache backend does support stamps as it doesn't override the _store_result() method of BaseKeyValueAttributeStore