Guessing the date format python

Question

I am writing a method in a Python module which tries to make live easier to the users. This method implements the creation of events in that calendar.

def update_event(start_datetime=None, end_datetime=None, description=None):
'''
Args:
  start_date: string datetime in the format YYYY-MM-DD or in RFC 3339
  end_date: string datetime in the format YYYY-MM-DD or in RFC 3339
  description: string with description (\n are transforrmed into new lines)
'''

If the user specifies the start_date or the end_date a check up should be made in order to determine if the date is in YYYY-MM-DD format or in the datetime RFC 3339 format.

if (start_date is not None):
    # Check whether we have an date or datetime value
    # Whole day events are represented as YYYY-MM-DD
    # Other events are represented as 2014-04-25T10:47:00.000-07:00
    whole_day_event = False
    try:
        new_start_time = datetime.datetime.strptime(start_date,'YYYY-MM-DD')
        # Here the event date is updated
        try:
            new_start_time = datetime.datetime.strptime(start_date,'%Y-%m-%dT%H:%M:%S%z')
            #Here the event date is updated
        except ValueError:
            return (ErrorCodeWhatever)
    except ValueError:
        return (ErrorCodeWhatever)

Is this a good way of doing this? Can I check what kind of date I am receiving in a nicer way? Thanks!

Answer 1

dateutil.parser.parse can be used to attempt to parse strings into datetime objects for you.

from dateutil.parser import parse

def update_event(start_datetime=None, end_datetime=None, description=None):
    if start_datetime is not None:
        new_start_time = parse(start_datetime)

        return new_start_time

d = ['23/04/2014', '24-04-2013', '25th April 2014']

new = [update_event(i) for i in d]

for date in new:
    print(date)
    # 2014-04-23 00:00:00
    # 2013-04-24 00:00:00
    # 2014-04-25 00:00:00

Answer 2

Extending @Ffisegydd answer you can also specify your target datetime format that you want like this :-

from dateutil.parser import parse

def update_event(start_datetime=None, end_datetime=None, description=None):
    if start_datetime is not None:
        new_start_time = parse(start_datetime)

        return new_start_time

d = ['06/07/2021 06:40:23.277000','06/07/2021 06:40','06/07/2021']

new = [update_event(i) for i in d]

for date in new:
    print(date.strftime('%Y/%m/%d %H:%M:%S.%f'))