If you use Tastypie with Django's timezone support turned on (i.e, you have USE_TZ = True in your settings.py), you will notice that Tastypie helpfully converts all dates and times in your resources to the timezone specified in your TIME_ZONE setting before returning them. If you care about internationalization, this is not the behavior you want. Tastypie encodes dates and times in the ISO8601 format by default. These dates and times have no timezone information attached to them, which means that the consumers of your API will have no idea how to correctly display them or convert them to other timezones.

This is what ISO8601 datetimes look like:

{
    "end_time": "2013-04-01T06:32:06",
    "start_time": "2013-04-01T00:30:00"
}

Both those datetimes are in the Asia/Kolkata (UTC+5:30) timezone. How can I tell? I can't. Unless I look in my settings.py. Not cool.

There are two solutions to this problem. First, you could add this line to your settings.py:

TASTYPIE_DATETIME_FORMATTING = 'rfc-2822'

This will cause Tastypie to format dates and times using the format specified in RFC2822. Your dates and times will now include timezone information:

{
    "end_time": "Mon, 1 Apr 2013 12:02:06 +0530",
    "start_time": "Mon, 1 Apr 2013 06:00:00 +0530"
}

The second solution, which is the solution I prefer, is simpler: use UTC everywhere on the server and let your API consumers deal with timezone conversions. Set your TIME_ZONE to 'UTC' and sleep easy.

If your API consumer is a web application, I highly recommend using Moment.js for all date and time operations.