mikecharles
2/8/2016 - 2:50 PM
Validate command line date argument in Python
Validate command line date argument in Python
def date_arg(value):
"""
Validate the --dates argument
Function will ensure that the --dates argument matches a given regex.
Possible values of the date are:
- YYYYMMDD (eg. 20120515)
- YYYYMMDD-YYYYMMDD (eg. 20140115-20140315)
- yesterday
- today
Parameters
----------
- value - *string* - automatically passed by the ArgumentParser object
Returns
-------
Returns the value back to the ArgumentParser object
Exceptions
----------
- argparse.ArgumentTypeError - if the passed argument doesn't match the
regex
"""
# Regex check
if not re.match('^(\d{8}|\d{8}-\d{8}|yesterday|today)$', value):
raise argparse.ArgumentTypeError("must be in the form MMDD, "
"MMDD-MMDD, yesterday, "
"or today".format(value))
# Make sure end date is >= start date
if re.match("\d{8}-\d{8}", value):
start, end = value.split('-')
if not end >= start:
raise argparse.ArgumentTypeError("The start date is less than the "
"end date")
return valueValidates a --dates argument in Python with the following possible formats:
- YYYYMMDD (eg. 20120515)
- YYYYMMDD-YYYYMMDD (eg. 20140115-20140315)
- yesterday
- today
To use this function, reference it in the argparse setup:
# ------------------------------------------------------------------------------
# Function to parse command-line arguments
#
def parse_args(argv):
"""
Parse the command line args
Note that the argv argument will be parsed instead of sys.argv because
the test suite will need to execute the main() function, and will
therefore need to pass the given arguments to that function, as opposed
to the main() function getting them from sys.argv.
Parameters
----------
- argv - *list of strings* - argument list containing the elements from
sys.argv, except the first element (sys.argv[0]) which is the script name
"""
# Create an ArgumentParser object
parser = argparse.ArgumentParser(add_help=False, usage='%(prog)s [OPTIONS]')
# Add a required argument group
group = parser.add_argument_group('required arguments')
# Add arguments
group.add_argument(
'-d', '--dates', dest='dates',
help='month and day of the valid date(s) to create stats for (YYYYMMDD or '
'YYYYMMDD-YYYYMMDD)',
metavar='<DATE(S)>', required=True, type=date_arg)
# If no options are set, print help and exit, otherwise parse args
if len(argv) <= 1:
parser.print_help()
sys.exit()
else:
args = parser.parse_args(argv)
# If the help option was set, print help and exit
if hasattr(args, 'help'):
parser.print_help()
sys.exit()
return args