Question

I have a script that has been written that I need to change the date on, when the script runs it outputs this message

output_messaging("*** DATA REFRESH FOR STREETWORKS DATA EXECUTED ON " + 
    str(datetime.date.today().day) + "/" + str(datetime.date.today().month) + "/" +            
    str(datetime.date.today().year) + " AT " + str(datetime.datetime.now().hour) + ':' +   
    str(datetime.datetime.now().minute) + ':' + str(datetime.datetime.now().second) + " ***\n\n")

Which gives

*** DATA REFRESH FOR STREETWORKS DATA EXECUTED ON 20/2/2012 AT 18:3 ***

I need the date converted to

20/Feb/2012 , how do i do this?

Answer 1

Use strftime for this — it’s way easier than doing a bunch of custom concatenation. There’s a table of formatting conventions here.

>>> s = "*** DATA REFRESH FOR STREETWORKS DATA EXECUTED ON "\
...     "%d/%b/%y AT %H:%M:%S ***\n\n"
>>> datetime.datetime.now().strftime(s)
'*** DATA REFRESH FOR STREETWORKS DATA EXECUTED ON 28/Feb/12 AT 11:44:03 ***\n\n'

As eumiro‘s answer indicates, you can also invert the above call with a slightly modified format string like so:

>>> s = "*** DATA REFRESH FOR STREETWORKS DATA EXECUTED ON "\
...     "{0:%d/%b/%y} AT {0:%H:%M:%S} ***\n\n"
>>> s.format(datetime.datetime.now())
'*** DATA REFRESH FOR STREETWORKS DATA EXECUTED ON 28/Feb/12 AT 13:41:10 ***\n\n'

This works because format simply calls the (shockingly under-documented) __format__ method of the datetime.datetime object. For example:

>>> datetime.datetime.now().__format__('The current month is %B')
'The current month is February'

This works for other types too:

>>> (16).__format__('x')
'10'

For more on __format__, see PEP 3101