#24485: Support for annotate(end=F('start') + F('duration'),
output_field=DateTimeField)
-------------------------------------+-------------------------------------
Reporter: yoyoma | Owner: nobody
Type: New feature | Status: new
Component: Database layer | Version: master
(models, ORM) |
Severity: Normal | Resolution:
Keywords: durationfield, | Triage Stage:
aggregation, annotation | Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Comment (by jarshwah):
What would you expect the SQL output of SUM(date_field) to be? Most
databases (all?) do not allow Sum(date). The argument to Sum has to be
numeric or convertable to numeric. Sum(interval) works for some backends.
What I suspect you really want though is this:
{{{
Ticket.objects.annotate(
expires_at=(F('active_at') + F('duration'),
output_field=models.DateTimeField())
)
}}}
Note that I've removed the Sum. We're now just adding two fields. I'm not
100% sure that this is supported on all backends, but if it's not it
should be. Also note that I've wrapped both F() expressions in brackets so
that I can apply the output_field to the combination of both. Can you give
that a go and report back please?
--
Ticket URL: <https://code.djangoproject.com/ticket/24485#comment:2>
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