django-celery-beat does not support nowfun in schedules

[celery]

django-celery-beat does not support nowfun in schedules

[mapleflow]

in django-celery-beat/model.py, it does not support nowfun, i think you can extend CrontabSchedule to solve your problem.

[nl3v]

Yes, I'm exploring options for extending it. Could pickle the lambda expression and store the string in CrontabSchedule, but that's pretty ugly... not sure how else to do it while making it compatible with already-existing schedules containing a nowfun, though.

Edit: One potential option would be to add a timezone field to CrontabSchedule. Then modify the schedule() method to create a nowfun that just uses datetime.now(timezone). This does not make the from_schedule() method start working correctly, however.

[Jorl17]

Hi.

Is there any predicted support for this feature? It is quite valuable to set events that are timezone aware.

Thanks

[thedrow]

I believe b6c0581 fixes this issue and it is available in 1.1.0.
Please let me know if I'm wrong and I'll reopen this issue.

[Jorl17]

We still get
TypeError: can't pickle function objects when trying to use
"schedule": crontab(hour=14, minute=38, nowfun=zonenowfun)

with zonenowfun = lambda: datetime.datetime.now(one_zone)

and 1.1.0

Any clues as to what is the problem?

[thedrow]

You cann't pickle lambdas. Use a normal function.

[Jorl17]

A normal function, in this particular context, has the same issue because it is being created within a for loop which iterates over different timezones (we create a different task for each timezone).

My main gripe with this issue is that this code was working with djcelery and it is pretty much taken from several online tutorials using celery and djcelery. When I upgraded a relatively legacy project to new celery versions (which have deprecated djcelery), this completely broke down, and there seems to be no way to do the same thing. The Celery documentation also does not state anything regarding limitations with nowfun.

Is there no planned fix for this? In my project we have worked around the issue, but it might hit other people. As an example, this thread often comes up in search results for celery and timezones.

[tartieret]

Hello,

As I needed this, I implemented a fork that allows to define CRON tasks in different timezones, by adding a timezone field to CrontabSchedule and subclassing celery.schedules.crontab. Let me know what you think !

See #99