Kinda confused on how messed Python datetime handling is, as I am importing strings and wanting to convert them to UTC, before potentially then outputting to users local tz

gistfile1.txt

# mydate is loaded via yaml.load() from a blob of yaml on the next line
# Date: 		2011-02-11 14:23:01

print mydate, 'offset: ', mydate.utcoffset()
# astimezone() called here outputs ValueError: astimezone() cannot be applied to a naive datetime
mydate = mydate.replace( tzinfo=pytz.timezone( 'Europe/London' ) )
print mydate, 'offset: ', mydate.utcoffset()
print mydate.astimezone(pytz.utc)

# outputs 

2011-02-12 14:23:01 offset:  None
2011-02-12 14:23:01-00:01 offset:  -1 day, 23:59:00
2011-02-12 14:24:01+00:00  

Right, how to fix:

mylocaltz = pytz.timezone( 'Europe/London' )

# What we expect the timezone to be ( global, sorry )
mydate = mylocaltz.localize( mydate )
# Then convert to UTC native
mydate = mydate.astimezone( pytz.utc )  

… and then you discover, yaml.load() strips hour offsets by normalising datetime into UTC, just doesn’t set the tzinfo.