#32661: An exception should be raised when trying to save an aware datetime/time
object even when the UTC offset isn't known.
-------------------------------------+-------------------------------------
Reporter: Armin Stepanjan | Owner: Abhyudai
Type: | Status: closed
Cleanup/optimization |
Component: Database layer | Version: 3.2
(models, ORM) |
Severity: Normal | Resolution: invalid
Keywords: timezone, datetime, | Triage Stage: Accepted
datetimefield, timefield, models |
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by Mariusz Felisiak):
* status: assigned => closed
* resolution: => invalid
Comment:
`datetime`/`time` objects with `tzinfo` which don't declare `utcoffset`
should be treated as naive. Closing as invalid per Aymeric's
[https://github.com/django/django/pull/14583#issuecomment-873395340
comment]:
{{{
This code has been working well for over 10 years so let's be careful.
Here's my analysis.
The docs say:
> A datetime object d is aware if both of the following hold:
>
> 1. d.tzinfo is not None
> 2. d.tzinfo.utcoffset(d) does not return None
>
> Otherwise, d is naive.
This hasn't changed this Python 2.7. (I didn't check further back.)
This was explicitly the implementation before
432678dbc1dd4f80203468d83bb0eb6c20ed5247.
Also, the documentation of datetime.utcoffset, `value.utcoffset()`
literally implemented as `None if value.tzinfo is None else
value.tzinfo.utcoffset(value)`.
As a consequence of the above, each of the following propositions are
strictly equivalent:
...
Therefore I believe the change proposed here is wrong for at least three
reasons:
- Any logic changes in this area will diverge from the definition in the
Python docs.
- The proposed logic is redundant — if `value.tzinfo is None`, then
`value.utcoffset() is None`: this is the first six words of the
documentation of datetime.utcoffset: "If tzinfo is None, returns None"; I
don't see how adding this redundant logic is an improvement.
- The proposed logic is wrong — if you wanted to go back to the previous
implementation, you should use `and` instead of `or` in `is_naive`.
Finally, I believe that have two one-liner convenience functions
implemented as `value.utcoffset() is None` and `value.utcoffset() is not
None` is fine. I don't see the need for adding a level of indirection and
the overhead of a function call here.
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/32661#comment:10>
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