Different methods of creating subcommands with argparse

sub01.py

#! /usr/bin/env python
# -*- coding: utf-8 -*-
# vim:fenc=utf-8
#
# Copyright © 2020 Tim Hughes <[email protected]>
#
# Distributed under terms of the MIT license.


"""
"""

import sys
import argparse
import logging

logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)


def server(args):

    try:
        logger.info(f"Running server {args}")
        pass
    except KeyboardInterrupt:
        logger.info("Exiting on KeyboardInterrupt")
    except Exception as exc:
        logger.info(f"Exiting on unknown error {exc}")


def initdb(args):
    logger.info(f"Initializing database")
    pass

def main():
    parser = argparse.ArgumentParser()
    subparsers = parser.add_subparsers()

    parser_server = subparsers.add_parser('serve', help='start the server')
    parser_server.add_argument('--config', help='path to configuration file')
    parser_server.set_defaults(func=server)

    parser_initdb = subparsers.add_parser('initdb', help='initialize data with table structure and seed data')
    parser_initdb.add_argument('--config', help='path to configuration file')
    parser_initdb.add_argument('--create-superuser', default=False,
                action='store_true', help='create a superuser account')
    parser_initdb.set_defaults(func=initdb)

    args = parser.parse_args()
    if hasattr(args, 'func'):
        args.func(args)
    else:
        parser.print_help()

if __name__ == "__main__":
    main()

sub02.py

#! /usr/bin/env python
# -*- coding: utf-8 -*-
# vim:fenc=utf-8
#
# Copyright © 2020 Tim Hughes <[email protected]>
#                  Chase Seibert https://chase-seibert.github.io
# based on https://chase-seibert.github.io/blog/2014/03/21/python-multilevel-argparse.html

"""

"""
import sys
import argparse
import logging

logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

class Cli:

    def __init__(self):
        parser = argparse.ArgumentParser()
        parser.add_argument('command', help='Subcommand to run')
        # parse_args defaults to [1:] for args, but you need to
        # exclude the rest of the args too, or validation will fail
        args = parser.parse_args(sys.argv[1:2])
        if not hasattr(self, args.command):
            printr('Unrecognized command')
            parser.print_help()
            exit(1)
        # use dispatch pattern to invoke method with same name
        getattr(self, args.command)()



    def server(self):
        parser = argparse.ArgumentParser(description='start the server')
        parser.add_argument('--config', help='path to configuration file')
        args = parser.parse_args(sys.argv[2:])


        try:
            logger.info(f"Running server {args}")
            # start server here
            pass
        except KeyboardInterrupt:
            logger.info("Exiting on KeyboardInterrupt")
        except Exception as exc:
            logger.info(f"Exiting on unknown error {exc}")


    def initdb(self, args):
        parser = argparse.ArgumentParser(
                description='initialize data with table structure and seed data')
        parser.add_argument('--config', help='path to configuration file')
        parser.add_argument('--create-superuser', default=False,
                action='store_true', help='create a superuser account')
        logger.info(f"Initializing Database {args}")
        # run initialize database code here
        pass

if __name__ == "__main__":
    Cli()

sub03.py

#! /usr/bin/env python
# -*- coding: utf-8 -*-
# vim:fenc=utf-8
#
# Copyright © 2020 Tim Hughes <[email protected]>
#
# Distributed under terms of the MIT license.

"""

"""
import argparse
import logging
import sys

logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

class Cli:

    def __init__(self):
        parser = argparse.ArgumentParser()
        subparsers = parser.add_subparsers()

        parser_server = subparsers.add_parser('serve', help='start the server')
        parser_server.add_argument('--config', help='path to configuration file')
        parser_server.set_defaults(func=self.server)

        parser_initdb = subparsers.add_parser('initdb',
                help='initialize data with table structure and seed data')
        parser_initdb.add_argument('--config', help='path to configuration file')
        parser_initdb.add_argument('--create-superuser', default=False,
                action='store_true', help='create a superuser account')
        parser_initdb.set_defaults(func=self.initdb)

        args = parser.parse_args()

        if hasattr(args, 'func'):
            args.func(args)
        else:
            parser.print_help()

    def server(self, args):

        try:
            logger.info(f"Running server {args}")
            # start server here
            pass
        except KeyboardInterrupt:
            logger.info("Exiting on KeyboardInterrupt")
        except Exception as exc:
            logger.info(f"Exiting on unknown error {exc}")


    def initdb(self, args):
        logger.info(f"Initializing Database {args}")
        # run initialize database code here
        pass


if __name__ == "__main__":
    Cli()