How to make a Django custom management command argument not required?

Question

I am trying to write a custom management command in django like below-

class Command(BaseCommand):      def add_arguments(self, parser):         parser.add_argument('delay', type=int)      def handle(self, *args, **options):         delay = options.get('delay', None)         print delay 

Now when I am running python manage.py mycommand 12 it is printing 12 on console. Which is fine.

Now if I try to run python manage.py mycommand then I want that, the command prints 21 on console by default. But it is giving me something like this-

usage: manage.py mycommand [-h] [--version]                            [-v {0,1,2,3}]                            [--settings SETTINGS]                            [--pythonpath PYTHONPATH]                            [--traceback]                            [--no-color]                            delay 

So now, how should I make the command argument "not required" and take a default value if value is not given?

Answer 1

One of the recipes from the documentation suggests:

For positional arguments with nargs equal to ? or *, the default value is used when no command-line argument was present.

So following should do the trick (it will return value if provided or default value otherwise):

parser.add_argument('delay', type=int, nargs='?', default=21) 

Usage:

$ ./manage.py mycommand 21 $ ./manage.py mycommand 4 4