ValueError: pytz.timezone('UTC').fromutc(datetime.utcnow())

[Alain Spineux]

>>> pytz.timezone('UTC').fromutc(datetime.utcnow())

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: fromutc: dt.tzinfo is not self
>>> pytz.timezone('Europe/Brussels').fromutc(datetime.utcnow())

datetime.datetime(2011, 10, 19, 9, 55, 47, 787937, tzinfo=<DstTzInfo
'Europe/Brussels' CEST+2:00:00 DST>)

Why does UTC fail ?
Bug or feature ?

Alain

[Stuart Bishop (stub)]

This exception is coming from Python - the default tzinfo.fromutc is designed to be called from datetime.astimezone()

[Stuart Bishop (stub)]

There doesn't seem any harm adding support for naive datetime instances and making behavior consistent.

[Alain Spineux (alain-spineux)]

I get naive datetime from SqlAlchemy in UTC and want to display it in the user 's local timezone, I used this

pytz.timezone(USER_LOCAL_TIMEZONE).fromutc(DATETIME_FROM_SQLALCHEMY)

If i'm wrong please tell me !

datetime.astimezone() works, but with some more code because it doesn't expect a naive datetime

>>> datetime.datetime.utcnow().replace(tzinfo=pytz.utc).astimezone(pytz.timezone('Europe/Brussels'))
datetime.datetime(2011, 11, 4, 10, 36, 51, 416512, tzinfo=<DstTzInfo 'Europe/Brussels' CET+1:00:00 STD>)
>>> datetime.datetime.utcnow().replace(tzinfo=pytz.utc).astimezone(pytz.timezone('utc'))
datetime.datetime(2011, 11, 4, 9, 37, 5, 320588, tzinfo=<UTC>)

Thanks

[Stuart Bishop (stub)]

Yes, I think the 'correct' version is complex but is what is supported by the base Python tzinfo implementation.

I have extended this in pytz-2011n so you should now be able to use your preferred, less cumbersome syntax with code expecting pytz tzinfo instances.

This pytz syntax also works if you need to use an older version:

utc = pytz.utc
brussels = pytz.timezone('Europe/Brussels')
utc.localize(datetime.utcnow()).astimezone(brussels)