Im trying to write a python program that I will run at the command line. I'd like the program to take a single input variable. Specifically, I would use a date in the form of 2014-01-28 (yyyy-mm-dd):
e.g. python my_script.py 2014-01-28
It seems argparse might be able to help me but I have found very little documentation regarding the module. Does anyone have experience with something like this?
There's lots of documentation in the standard library, but generally, something like:
import argparse
import datetime
parser = argparse.ArgumentParser()
parser.add_argument(
'date',
type=lambda s: datetime.datetime.strptime(s, '%Y-%m-%d'),
)
# For testing. Pass no arguments in production
args = parser.parse_args(['2012-01-12'])
print(args.date) # prints datetime.datetime object
parse_args, it will be used as if those arguments were passed on the command line. Under normal circumstances (if you don't pass anything) argparse uses sys.argv[1:]. See docs.python.org/dev/library/…
parser.parse_args('this is a test string'.split()) is another test option. It's equivalent to parse_args(['this','is',...]), and in a few edge conditions better.choices are best defined. The real reason I favor split is it can save typing. shlex.split would be a better choice if I wanted to simulate how the shell creates sys.argvAs of Python 3.7, a (marginally) more convenient option is fromisoformat: https://docs.python.org/3/library/datetime.html#datetime.date.fromisoformat
Using it, you can replace the relevant line in mgilson's code with this:
parser.add_argument('date', type=datetime.date.fromisoformat)
(I would also add a help argument to this invocation of add_argument, and mention that the input should be in ISO format.)
parser.add_argument('date', type=datetime.datetime.fromisoformat, help='ISOformat - YYYY-MM-DD:HH:mm:ss')