How to solve the strptime() caused naive datetime RuntimeWarning?

Question

I am trying to code without throwing any warnings in my console. So far I have been pretty good at avoiding it until this one case, which seems like a chicken and egg situation to me.

from datetime import datetime as dt 

last_contacted = "19/01/2013"
current_tz = timezone.get_current_timezone()
date_time = dt.strptime(last_contacted, get_current_date_input_format(request))
date_time = current_tz.localize(date_time)

The third line is throwing this warning:

RuntimeWarning: DateTimeField received a naive datetime (2013-01-19 00:00:00) while time zone support is active.)

Its kind of odd, since I need to convert the unicode into a datetime first before I can convert the datetime object into an datetime-aware object (with timezone support) in the forth line.

Any suggestions from experts?

Thanks

UPDATE:

def get_current_date_input_format(request):
    if request.LANGUAGE_CODE == 'en-gb':
        return formats_en_GB.DATE_INPUT_FORMATS[0]
    elif request.LANGUAGE_CODE == 'en':        
        return formats_en.DATE_INPUT_FORMATS[0]

Answer 1

From the comments to your question I am guessing that what you really have in your code is something like this:

from datetime import datetime as dt 

last_contacted = "19/01/2013"
current_tz = timezone.get_current_timezone()
model_instance.date_time = dt.strptime(last_contacted, get_current_date_input_format(request))
model_instance.date_time = current_tz.localize(date_time)

where model_instance is an instance of a Model which has a DateTimeField named date_time.

class MyModel(models.Model)
    ....
    date_time = DateTimeField()

The Python datetime.strptime function returns a naive datetime object which you are attempting to assign to the DateTimeField which is then generating a warning because the use of non-naive datetime objects is incorrect when timezone support is enabled.

If you combine the calls to strptime and localize on a single line, then the complete calculation of converting from a naive datetime to non-naive datetime is done before assigning to date_time and so you won't get an error in this case.

Additional note: Your get_current_date_input_format function should return some default timezone to use in the event that there is no timezone in the request, otherwise the strptime call will fail.