Python argparse how to pass False from the command line?

Question

I am trying to sort out how to pass the boolean value False from the command line to the argparser. My origninal code looked like:

import argparse
parser = argparse.ArgumentParser(allow_abbrev=True)
parser.add_argument('-data', default=True, type=bool, help='uses the history file')
args = parser.parse_args(sys.argv[1:])

From the command line, I typed: python myscript.py -data False

Also variations with single & double quotes around False. When I examine the contents of the args namespace, args.data is always True.

So I changed the argument definition from bool to str, with a string "True" default as shown below:

parser.add_argument('-data', default="True", type=str, help='uses the history file')

I then added some massaging of the args to get the boolean value I really wanted:

if re.search("f", args.data, re.I):
   args.data = False
else:
   args.data = True

This workaround does work. Is there a better way to do this?

Answer 1

You can use the store_false or store_true parameter to add_argument (see the argparse documentation). For example, if you want the default to be True then you could add an argument with action='store_false':

parser.add_argument('--no-data', action='store_false', help="don't use the history file")

Then args.no_data will be False if you run python command.py --no-data and True if you run python command.py without the --no-data argument.

Answer 2

def my_bool(s):
    return s != 'False'

parser.add_argument('-data',default=True,type=my_bool)