#32269: parse_duration() ISO string sign is ignored when the timedelta only has
days
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Reporter: wanaryytel | Owner: nobody
Type: Bug | Status: new
Component: Utilities | Version: 3.1
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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I'm pretty sure that this is a bug even though I'm not an expert on the
ISO 8601 standard. The sign of a timedelta string will be ignored by
`django.utils.dateparse.parse_duration` if the input string only contains
days. Compare the following (notice the minus signs):
{{{
In [4]: timedelta(days=-1)
Out[4]: datetime.timedelta(days=-1)
In [5]: td = timedelta(days=-1)
In [6]: duration_iso_string(td)
Out[6]: '-P1DT00H00M00S'
In [7]: parse_duration(duration_iso_string(td))
Out[7]: datetime.timedelta(days=1) # <-- Why is this 1 and not -1?
In [8]: td = timedelta(days=-1, microseconds=1)
In [9]: duration_iso_string(td)
Out[9]: '-P0DT23H59M59.999999S'
In [10]: parse_duration(duration_iso_string(td))
Out[10]: datetime.timedelta(days=-1, microseconds=1)
}}}
I guess the problem is in django/utils/dateparse.py line 147 that reads
`return days + sign * datetime.timedelta(**kw)`.
However, if `datetime.timedelta(**kw)` ends up being zero (`timedelta(0)`)
then the sign multiplication ends up in zero, not `-0`. This is just a
preliminary quick look though and maybe the problem is something else.
--
Ticket URL: <https://code.djangoproject.com/ticket/32269>
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