argparse with 2 date arguments

Question

I want to create a program which selects users from a database between 2 dates given on the command line. I have:

import argparse

parser = argparse.ArgumentParser()
group = parser.add_mutually_exclusive_group()

group.add_argument("--date1","-d1",help="Show users between dates",type=str)
group.add_argument("--date2","-d2",help="Show users between dates",type=str)

if args.date1 and args.date2:
    DataCalculation.show_users_between_date(args.date1,args.date2)

And in my DataCalculation I have query to get users between 2 dates. Unfortunately this solution doesnt work and I get error: argument --date2/-d2: not allowed with argument --date1/d1

I was running program like: py main.py -d1 1994-01-01 -d2 1995-12-31

I was thinking that I can split these 2 dates to list in function and give only 1 argument like: py main.py -d 1994-01-01 1995-12-31, but this idea doesn't work too. Is there an easy way to use 2 arguments which have to be given together?

You've asked for `add_mutually_exclusive_group`. That means you can only select one item for that group. If you want to allow both, don't make them mutually exclusive. — larsks, Aug 06 '20 at 15:51
Yeah... your code doesn't work as is. You want to read this though: https://docs.python.org/3/library/argparse.html#nargs — tomjn, Aug 06 '20 at 15:52

wjandrea · Accepted Answer · 2020-08-06T16:02:39.730

You're looking for inclusivity, not exclusivity. You can accomplish that by using nargs=2 with one option, like your second case.

import argparse

parser = argparse.ArgumentParser()
parser.add_argument(
    "--date",
    "-d",
    nargs=2,
    metavar=('start', 'end'),  # Describes each argument
    help="Show users between start and end dates",
    )
args = parser.parse_args()
print(args)

Usage:

$ ./tmp.py -d 1994-01-01 1995-12-31
Namespace(date=['1994-01-01', '1995-12-31'])

$ ./tmp.py -d 1994-01-01
usage: tmp.py [-h] [--date start end]
tmp.py: error: argument --date/-d: expected 2 arguments

$ ./tmp.py -d 1994-01-01 1995-12-31 1998
usage: tmp.py [-h] [--date start end]
tmp.py: error: unrecognized arguments: 1998

$ ./tmp.py -h
usage: tmp.py [-h] [--date start end]
optional arguments:
  -h, --help            show this help message and exit
  --date start end, -d start end
                        Show users between start and end dates

score 1 · Answer 2 · answered Aug 06 '20 at 15:51

You could use

import argparse

parser = argparse.ArgumentParser()
group = parser.add_mutually_exclusive_group()

group.add_argument("--daterange","-dr",help="Show users between dates",type=str)
args = parser.parse_args()

date1, date2 = args.daterange.split()
print(date1)

And then quotes around your arguments as in

python test.py -dr "1994-01-01 1995-12-31"

Which yields with the above snippet:

1994-01-01

argparse with 2 date arguments

2 Answers2