#22549 closed Bug (worksforme)
DateTimeField raises timezone awareness related RuntimeWarnings when it should'nt
Reported by: | Owned by: | nobody | |
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Component: | Database layer (models, ORM) | Version: | |
Severity: | Normal | Keywords: | |
Cc: | matias@… | Triage Stage: | Accepted |
Has patch: | no | Needs documentation: | no |
Needs tests: | no | Patch needs improvement: | no |
Easy pickings: | no | UI/UX: | no |
Description
I've experienced some issues with wrong RuntimeWarnings about naive datetimes being raised when the
datetime I was using was perfectly timezone aware and I think I found the reason why:
In django/db/models/fields/init.py file, inside the definition of DateTimeField.to_python method,
the timezone awareness of a datetime is checked calling the isinstance function.
if isinstance(value, datetime.date): value = datetime.datetime(value.year, value.month, value.day) if settings.USE_TZ: # For backwards compatibility, interpret naive datetimes in # local time. This won't work during DST change, but we can't # do much about it, so we let the exceptions percolate up the # call stack. warnings.warn("DateTimeField %s.%s received a naive datetime " "(%s) while time zone support is active." % (self.model.__name__, self.name, value), RuntimeWarning)
Is true that, as said here https://docs.python.org/2.7/library/datetime.html#available-types,
"objects of the date type are always naive", but is wrong to use isinstance since all datetime.datetime
objects are also instances of datetime.date because datetime.datetime is a subclass of datetime.date
(which I think is confusing since breakes the OOP intuition that says that class inheritance should
describe "is a" relationships).
A posible solution is to compare using type(value) == datetime.date or, more clearly, check using django.utils.is_naive
Change History (2)
comment:1 by , 11 years ago
Easy pickings: | unset |
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Triage Stage: | Unreviewed → Accepted |
comment:2 by , 11 years ago
Resolution: | → worksforme |
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Status: | new → closed |
Look two lines above -- the complete code is:
If
value
is adatetime.datetime
the first branch returns, you don't hit the second branch.