Artikel ini juga tersedia dalam terjemahan Bahasa indonesia dengan judul Memakai argparse untuk memberikan argumen pada skrip python.

While doing some QA tasks, I got a case which I need to add and delete domain names from hundreds of categorized text files time after time.

Since it was repetitive and cost me time to perform it, I decided to create python script for automating that case.

Inspired by simplicity of linux command: ls which has several arguments with distinct functionalities, I also want my python script to be able to run multiple functions.

To accommodate that, I need to separate the input arguments.

After doing internet research, I found argparse solving this issue. With argparse library, user can pass arguments into python script.

Let’s write this argparse script.

What the program does:

1. Provide help argument for new user
2. Receive arguments for particular functions: add and delete domain name

Step 1: Create argument parser

Create a python file and save it as argparse_example.py

import argparse

def process_argument():
    parser = argparse.ArgumentParser(description=r"Script to expedite QA process with 2 functions as described below.")

# TODO : Create sub parser for each function menus

# TODO : Get arguments on main program

TODO comments are just skeleton for the program.

Step 2: Create subparser for each function menus

import argparse

def process_argument():
    parser = argparse.ArgumentParser(description=r"Script to expedite QA process with 2 functions as described below.")

    subparsers = parser.add_subparsers(dest='options', help='choose script action')

    add_parser = subparsers.add_parser('add', help='adding domains to destination category')
    add_parser.add_argument('-n', '--domain_name', action='store', help='Store a domain value')
    add_parser.add_argument('-d', '--destination_category', action='store', help='file path of destination domain')

    delete_parser = subparsers.add_parser('delete', help='deleting domains from source category')
    delete_parser.add_argument('-n', '--domain_name', action='store', help='Store a domain value')
    delete_parser.add_argument('-s', '--source_category', action='store', help='file path of source domain')

    try:
        return parser.parse_args()
    except IOError, msg:
        parser.error(str(msg))

# TODO : Get arguments on main program

Each subparser has its own input arguments with functionality description.

Step 3: Get arguments on main program

import argparse

def process_argument():
    parser = argparse.ArgumentParser(description=r"Script to expedite QA process with 2 functions as described below.")

    subparsers = parser.add_subparsers(dest='options', help='choose script action')

    add_parser = subparsers.add_parser('add', help='adding domains to destination category')
    add_parser.add_argument('-n', '--domain_name', action='store', help='Store a domain value')
    add_parser.add_argument('-d', '--destination_category', action='store', help='file path of destination domain')

    delete_parser = subparsers.add_parser('delete', help='deleting domains from source category')
    delete_parser.add_argument('-n', '--domain_name', action='store', help='Store a domain value')
    delete_parser.add_argument('-s', '--source_category', action='store', help='file path of source domain')

    try:
        return parser.parse_args()
    except IOError, msg:
        parser.error(str(msg))

def main():
    args = process_argument()

    if args.options == 'delete':
        print 'Deleting ' + args.domain_name + ' from ' + args.source_category + ' is succeeded.'
    elif args.options == 'add':
        print 'Adding ' + args.domain_name + ' on ' + args.destination_category + ' is succeeded.'

if __name__ == "__main__":
    main()

Adding the feedback on main program to notify user that the argument is working as expected.

Final result

Running program

Perform global help function: python argparse_example.py -h

Perform help for each function

Add: python argparse_example.py add -h

Delete: python argparse_example.py delete -h

Perform add domain name function: python argparse_example.py add -n testing.com -d someCategory

Perform delete domain name function: python argparse_example.py delete -n testing.com -s someCategory

Further reading

Basic concept:

• https://pymotw.com/2/argparse/
• http://tricksntweaks.blogspot.co.id/2013/05/advance-argument-parsing-in-python.html
• https://mkaz.tech/python-argparse-cookbook.html

Subparsing concept:

• http://stackoverflow.com/questions/4575747/get-selected-subcommand-with-argparse
• http://stackoverflow.com/questions/8250010/argparse-identify-which-subparser-was-used
• http://www.prschmid.com/2013/07/parsing-arguments-in-python-with.html
• http://tylerturk.com/argparse-with-custom-subparsing/