How to prevent usernames from containing @/./+/-/_.?

Question

I\'m using django-allauth, and for some reason the username default allows:

\"letters, digits and @/./+/-/_.\"

How can I ensure usernames are strictly alphanumer

Answer 1

You could use a regex expression to ensure that a username contains only allowed characters. For alphanumeric characters the following should do the trick:

import re
def is_valid_username(username):
    pattern = re.compile('([a-zA-Z]+|\d+)')
    return ''.join(re.findall(pattern, username)) == username

Here's an example of the output:

username_list = ["WhatAGre4tUsern4me", "548ThatISAgoodUsername005",
                 "CheckOutMy_Username", "It'sAUsern@me"]
print([is_valid_username(u) for u in username_list])
>>> [True, True, False, False]