Specify format for input arguments argparse python

Question

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

Answer 1

Per the documentation:

The type keyword argument of add_argument() allows any necessary type-checking and type conversions to be performed ... type= can take any callable that takes a single string argument and returns the converted value

You could do something like:

def valid_date(s):
    try:
        return datetime.strptime(s, "%Y-%m-%d")
    except ValueError:
        msg = "Not a valid date: '{0}'.".format(s)
        raise argparse.ArgumentTypeError(msg)

Then use that as type:

parser.add_argument("-s", 
                    "--startdate", 
                    help="The Start Date - format YYYY-MM-DD", 
                    required=True, 
                    type=valid_date)