Knowing when cache expires or DurationField is done

[Yoo]

1. Using celery to make a replacement cache when that specific expires, but not sure how to do it.

2. Along the same lines, I need to also know when a DurationField is at "zero." Not sure how a DurationField works though. Again, need celery to be able to execute something when a specific record has its attribute hit the "zero" on its "timer."

If there are other ways, lemme know!

Thanks!

[Yoo]

Just to clarify the first point: celery is "updating" the cache with new info once the cache expires; hence the need for the cache to expire. I thought about using a DB table, but also thought about how wasteful it would be to keep a DurationField (which I still don't know how to use) to log when celery should execute a task.