EmailType: a custom argparse type to validate email addresses

argparse_email_type.py

"""
A custom type for argparse, to facilitate validation of email addresses.

Inspired by this SO question: http://stackoverflow.com/questions/14665234/argparse-choices-structure-of-allowed-values
and this gist: https://gist.github.com/gurunars/449edbccd0de1449b71524c89d61e1c5
"""
import re
import argparse


class EmailType(object):
    """
    Supports checking email agains different patterns. The current available patterns is:
    RFC5322 (http://www.ietf.org/rfc/rfc5322.txt)
    """

    patterns = {
        'RFC5322': re.compile(r"^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$"),
    }

    def __init__(self, pattern):
        if pattern not in self.patterns:
            raise KeyError('{} is not a supported email pattern, choose from:'
                           ' {}'.format(pattern, ','.join(self.patterns)))
        self._rules = pattern
        self._pattern = self.patterns[pattern]

    def __call__(self, value):
        if not self._pattern.match(value):
            raise argparse.ArgumentTypeError(
                "'{}' is not a valid email - does not match {} rules".format(value, self._rules))
        return value


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument('email', type=EmailType('RFC5322'))
    args = parser.parse_args()

    print(args.email)

if __name__ == '__main__':
    main()

Thanks for creating this! Here’s a simpler variation for anyone wanting something more succinct:

import re
import argparse

RE_EMAIL = re.compile(r"^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$")


def email_type(value):
    if not RE_EMAIL.match(value):
        raise argparse.ArgumentTypeError(f"'{value}' is not a valid email")
    return value

def main():
    parser = argparse.ArgumentParser()
    parser.add_argument('email', type=email_type)
    args = parser.parse_args()

    print(args.email)

if __name__ == '__main__':
    main()