Handle spaces in argparse input

Using python and argparse, the user could input a file name with -d as the flag.

parser.add_argument("-d", "--dmp", default=None)

However, this failed when the path included spaces. E.g.

-d C:\SMTHNG\Name with spaces\MORE\file.csv

NOTE: the spaces would cause an error (flag only takes in 'C:SMTHNG\Name' as input).

error: unrecognized arguments: with spaces\MORE\file.csv

Took me longer than it should have to find the solution to this problem... (did not find a Q&A for it so I'm making my own post)

For those who can't parse arguments and still get "error: unrecognized arguments:" I found a workaround:

parser.add_argument('-d', '--dmp', nargs='+', ...)
opts = parser.parse_args()

and then when you want to use it just do

' '.join(opts.dmp)

Simple solution: argparse considers a space filled string as a single argument if it is encapsulated by quotation marks.

This input worked and "solved" the problem:

-d "C:\SMTHNG\Name with spaces\MORE\file.csv"

NOTICE: argument has "" around it.

Bumped into this problem today too.

-d "foo bar"

didn't help. I had to add the equal sign

-d="foo bar"

and then it did work.

After some experiments (python 2.7 Win10) I found out that the golden rule is to put quotes ("") around arguments which contain spaces and do NOT put if there are no spaces in argument. Even if you are passing a string/path. Also putting a single quotes ('') is a bad idea, at least for Windows.

Small example: python script.py --path ....\Some_Folder\ --string "Here goes a string"

A common mistake when passing forwarding bash script arguments is to forget double quotes. for example writting this:

ARGS="C:\SMTHNG\Name with spaces\MORE\file.csv"
mypythonscript  -d $ARGS

while it should be

ARGS="C:\SMTHNG\Name with spaces\MORE\file.csv"
mypythonscript -d "$ARGS"

There are 2 important points here (from my perspective):

1. You do not want to replace all the spaces in the argument input.
2. You want to use argparse interface.

My best aproax would be to use an argparse.Action with the function strip for the string:

import argparse

class StripArgument(argparse.Action):
    def __call__(self, parser, namespace, values, option_string=None):
        setattr(namespace, self.dest, values.strip())

parser = argparse.ArgumentParser(
    prog=f"your program", description=__doc__,
    formatter_class=argparse.RawDescriptionHelpFormatter,
    epilog="See '<command> --help' to read about a specific sub-command.")
parser.add_argument(
    "-n", "--variable-name", type=str, default='vx', action=StripArgument,
    help="Variable name inside something (default: %(default)s)")

You need to surround your path with quotes such as:

python programname.py -path "c:\My path with spaces"

In the argument parse you get a list with one element. You then have to read it like:

path = args.path[0]