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 ofadd_argument()
allows any necessary type-checking and type conversions to be performed ... The argument totype
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'