Convert UTC native datetime to Eastern tine native datetime for pymongo

Question

I need to query a mongodb that saves it's dates in the local timezone (Eastern), but I'm working in UTC. How can I convert a UTC native datetime to Eastern tine native datetime for pymongo, accounting for daylight savings?

Answer 1

After a bit more goggling, I found this question , which led me to the answer.

1. Set the UTC timezone to the native UTC datetime
2. Convert that to eastern time
3. Get the UTC offset of that as a timedelta
4. Add that to the original datetime

 ET = pytz.timezone("America/New_York") def utc_to_et(utcdt): utc_with_tz = utcdt.replace(tzinfo=pytz.UTC) offset = utc_with_tz.astimezone(ET).utcoffset() return utcdt + offset 

Answer 2

To convert a naive datetime object that represents time in UTC to different timezone:

from datetime import datetime
import pytz

tz = pytz.timezone('US/Eastern') #NOTE: deprecated timezone name

naive_utc_dt = datetime.utcnow()                # naive datetime object
utc_dt = naive_utc_dt.replace(tzinfo=pytz.utc)  # aware datetime object
east_dt = utc_dt.astimezone(tz)                 # convert to Eastern timezone
naive_east_dt = east_dt.replace(tzinfo=None) #XXX use it only if you have to

Note: if the source timezone is not UTC then .localize() , .normalize() method should be used.

pytz allows you to handle utc offset changes (not only due to DST) for a given region: today, in the past (many libraries fail here).

Answer 3

I'm not sure if this is what you mean:

http://docs.python.org/2/library/datetime.html#datetime.datetime.astimezone

It allow you to change datetime from one timezone to another.

Answer 4

Also note that if Mongo connection is not opened as timezone aware you just get naive datetime out of the database.

from pymongo import Connection
# Create a timezone aware connection
connection = Connection('localhost', 27017, tz_aware=True)