import pytz
from pyrfc3339.utils import timezone, timedelta_seconds
def generate(dt, utc=True, accept_naive=False, microseconds=False):
'''
Generate an :RFC:`3339`-formatted timestamp from a
:class:`datetime.datetime`.
>>> from datetime import datetime
>>> generate(datetime(2009,1,1,12,59,59,0,pytz.utc))
'2009-01-01T12:59:59Z'
The timestamp will use UTC unless `utc=False` is specified, in which case
it will use the timezone from the :class:`datetime.datetime`'s
:attr:`tzinfo` parameter.
>>> eastern = pytz.timezone('US/Eastern')
>>> dt = eastern.localize(datetime(2009,1,1,12,59,59))
>>> generate(dt)
'2009-01-01T17:59:59Z'
>>> generate(dt, utc=False)
'2009-01-01T12:59:59-05:00'
Unless `accept_naive=True` is specified, the `datetime` must not be naive.
>>> generate(datetime(2009,1,1,12,59,59,0))
Traceback (most recent call last):
...
ValueError: naive datetime and accept_naive is False
>>> generate(datetime(2009,1,1,12,59,59,0), accept_naive=True)
'2009-01-01T12:59:59Z'
If `accept_naive=True` is specified, the `datetime` is assumed to be UTC.
Attempting to generate a local timestamp from a naive datetime will result
in an error.
>>> generate(datetime(2009,1,1,12,59,59,0), accept_naive=True, utc=False)
Traceback (most recent call last):
...
ValueError: cannot generate a local timestamp from a naive datetime
'''
if dt.tzinfo is None:
if accept_naive is True:
if utc is True:
dt = dt.replace(tzinfo=pytz.utc)
else:
raise ValueError("cannot generate a local timestamp from " +
"a naive datetime")
else:
raise ValueError("naive datetime and accept_naive is False")
if utc is True:
dt = dt.astimezone(pytz.utc)
timestamp = dt.strftime('%Y-%m-%dT%H:%M:%S')
if microseconds is True:
timestamp += dt.strftime('.%f')
if dt.tzinfo is pytz.utc:
timestamp += 'Z'
else:
timestamp += timezone(timedelta_seconds(dt.tzinfo.utcoffset(dt)))
return timestamp