+1 for deprecation as well.
`days_ago()` was removed from example DAGs and other documentation since it
was mainly being used for dynamic `start_date` values which is not a best
practice in DAG authoring. Seemed to create more confusion and odd behavior
than value.
On Tue, Dec 28, 2021 at 7:00 PM Jarek Potiuk <ja...@potiuk.com> wrote:
> I'd be for deprecating it. It's too easy to use with too much too
> loose and too little value. I see no real "business" value in it.
>
> On Tue, Dec 28, 2021 at 5:27 PM Daniel Standish
> <daniel.stand...@astronomer.io.invalid> wrote:
> >
> > Yeah that's correct. Sorry, I should have used `pendulum.today`. But
> yeah also equivalent to `pendulum.today('UTC').add(days=-N)` (while
> `days_ago` uses timedelta it's the same when there's no DST is involved)
> >
> >
> > On Tue, Dec 28, 2021, 1:59 AM Ash Berlin-Taylor <a...@apache.org> wrote:
> >>
> >> days_ago is not just the same as utcnow minus N days, it is always
> "truncated" to the start of the day, so it's closer to
> "utcnow().replace(hour=0, minute=0, second=0) - timedelta(n)”
> >>
> >>
> >> On 28 December 2021 00:08:53 GMT, Daniel Standish
> <daniel.stand...@astronomer.io.INVALID> wrote:
> >>>
> >>> I recall some time ago we removed `days_ago` from all example dags.
> Not sure why we didn't also deprecate it.
> >>>
> >>> For reference, `days_ago(N)` returns utcnow minus N days.
> >>>
> >>> There's a PR to make it return a value in the default timezone, so
> that when you use it in an expression for dag `start_date`, the dag will be
> in the default timezone.
> >>>
> >>> I don't want to get into the merits of that here. But even assuming
> that this would be desirable, there's still some ambiguity we'd have to
> resolve. Namely, should we return `now minus N 24-hour periods` (as `now -
> timedelta(N)` would do) or should we return now minus N days (as
> pendulum.now().add(days=-N) would do)? Because of DST the two different
> approaches result in values that differ by 1 hour.
> >>>
> >>> What I do want to explore here is whether folks think we can / should
> just deprecate the function entirely. Personally this would be my
> preference. Using `days_ago(5)` is not much more convenient than
> `dttm.add(days=-N)`. And the latter has the benefit that it is
> unambiguous, doesn't make assumptions, and doesn't get in the way between
> user and library.
> >>>
> >>> So my proposal would be, don't change the behavior of `days_ago` and
> deprecate it with removal targeted in 3.0.
> >>>
>
