["python","argparse"]
Specify date format for Python argparse input arguments

I have a Python script that requires some command line inputs and I am using argparse for parsing them. I found the documentation a bit confusing and couldn't find a way to check for a format in the input parameters. What I mean by checking format is explained with this example script: parser.add_argument('-s', "--startdate", help="The Start Date - format YYYY-MM-DD ", required=True) parser.add_argument('-e', "--enddate", help="The End Date format YYYY-MM-DD (Inclusive)", required=True) parser.add_argument('-a', "--accountid", type=int, help='Account ID for the account for which data is required (Default: 570)') parser.add_argument('-o', "--outputpath", help='Directory where output needs to be stored (Default: ' + os.path.dirname(os.path.abspath(__file__))) I need to check for option -s and -e that the input by the user is in the format YYYY-MM-DD. Is there an option in argparse that I do not know of which accomplishes this?
Per the documentation: The type keyword argument of add_argument() allows any necessary type-checking and type conversions to be performed ... The argument to type can be any callable that accepts a single string. You could do something like: import argparse import datetime def valid_date(s: str) -> datetime.datetime: try: return datetime.datetime.strptime(s, "%Y-%m-%d") except ValueError: raise argparse.ArgumentTypeError(f"not a valid date: {s!r}") Then use that as type: parser.add_argument( "-s", "--startdate", help="The Start Date - format YYYY-MM-DD", required=True, type=valid_date ) If the user supplies an invalid value, the feedback will look like: error: argument -s/--startdate: not a valid date: 'foo'