Google App Engine, parsedatetime and TimeZones

I'm working on a Google App Engine / Django app and I encountered the following problem: In my html I have an input for time. The input is free text - the user types "in 1 hour" or "tomorrow at 11am". The text is then sent to the server in AJAX, which parses it using thi开发者_开发问答s python library: http://code.google.com/p/parsedatetime/. Once parsed, the server returns an epoch timestamp of the time. Here is the problem - Google App Engine always runs on UTC. Therefore, lets say that the local time is now 11am and the UTC time is 2am. When I send "now" to the server it will return "2am", which is good because I want the date to be received in UTC time. When I send "in 1 hour" the server will return "3am" which is good, again. However, when I send "at noon" the server will return "12pm" because it thinks that I'm talking about noon UTC - but really I need it to return 3am, which is noon for the request sender.. I can pass on the TZ of the browser that sends the request, but that wont really help me - the parsedatetime library wont take a timezone argument (correct me if I'm wrong). Is there a walk around this? Maybe setting the environments TZ somehow?

Thanks!

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What you could do is add the difference using a timedelta object (http://docs.python.org/library/datetime.html)

The offset

here's some (very rough) code to give you the idea:

import parsedatetime
import datetime

my_users_timezone = whatever #replace this with a string that will make sense in the offsets dictionary

utc_timezone_offsets_in_hours = {
   'utc' : 0,
   'pacific' : -8,
   # etc
}

parsed_time = parsedatetime.whatever(input_string)
offset_hours = utc_utc_timezone_offsets_in_hours[my_users_timezone]
final_time = parsed_time + datetime.timedelta(hours=offset_hours)
return final_time

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parsedatetime's parse routine expects a timetuple() as the sourceTime parameter and should carry over any timezone information you include in it as I don't recall writing any code that overrode it. If it doesn't then it's a bug and let me know.

You can use code like how the answer above suggested for now to add the TZ offset after the parse() routine returns what it has determined the datetime to be:

import parsedatetime as pdt

cal = pdt.Calendar()

start  = datetime.datetime.now().timetuple()

parsed, flag = cal.parse('in 1 hr', start)

then you can take the timetuple value of parsed and use timedelta to add your offset hours