Python/Django timestamp including milliseconds

Question

I need to print (and pass to an external API) the current datetime in the following format:

DD-MM-YYYY:HH:MM:SS:SSS

where the last 3 SSS imply milliseconds. I know how to print the current datetime up to microseconds using Python's strftime as in the below manage.py shell Django shell session:

In [1]: from django.utils import timezone

In [2]: timezone.now()
Out[2]: datetime.datetime(2013, 8, 5, 15, 26, 10, 71046, tzinfo=<UTC>)

In [3]: timezone.now().strftime('%d-%m-%Y:%H:%M:%S:%f')
Out[3]: '05-08-2013:15:28:31:647504'

How to print the ending :SSS part so that the above string becomes:

'05-08-2013:15:28:31:123'

ie displaying milliseconds (using only 3 digits) rather than microseconds?

Answer 1

Add the milliseconds separately by dividing the timestamp microseconds by 1000:

tznow = timezone.now()
'{:%d-%m-%Y:%H:%M:%S}.{:03d}'.format(tznow, tznow.microsecond // 1000)

Demo:

>>> from django.utils import timezone
>>> tznow = timezone.now()
>>> '{:%d-%m-%Y:%H:%M:%S}.{:03d}'.format(tznow, tznow.microsecond // 1000)
'05-08-2013:15:36:00.339'