PlainASCIIUsernameValidator

MyValidator.py

@deconstructible
class PlainASCIIUsernameValidator(validators.RegexValidator):
    regex = good_username_regex
    message = _(
        'Enter a valid username. This value may contain only English letters and numbers'
    )
    flags = re.ASCII
    
def random_username():
    return uuid.uuid4().hex[:username_max_length]
    
class User(AbstractUser, Demographics, HomeStudyInfoMultipleItemsThru, Ram, Ethics):
    username_validator = PlainASCIIUsernameValidator()

    username = models.CharField(
        'username',
        default=random_username,
        max_length=username_max_length,
        unique=True,
        help_text=_('Required. 20 characters or fewer. English letters and digits only.'),
        validators=[username_validator],
        error_messages={
            'unique': _("A user with that username already exists."),
        },
    )

good_username_regex = r'^[\w]+\Z'