How to add max_length to allauth username

Question

I\'m using Django allauth as my user account framework for my django site. The docs show there is an ACCOUNT_USERNAME_MIN_LENGTH however there is no ACCOUNT_USERNAME_MAX_L

Answer 1

I would like to explain why there is no ACCOUNT_USERNAME_MAX_LENGTH. If you open source code you will see that max_length validator comes from username model field https://github.com/pennersr/django-allauth/blob/330bf899dd77046fd0510221f3c12e69eb2bc64d/allauth/account/forms.py#L277

username_field.max_length = get_username_max_length()

Where get_username_max_length is function that actually pulls max_length value from User model https://github.com/pennersr/django-allauth/blob/8fbbf8c1d32832d72de5ed1c7fd77600af57ea6f/allauth/utils.py#L64

def get_username_max_length():
    from .account.app_settings import USER_MODEL_USERNAME_FIELD
    if USER_MODEL_USERNAME_FIELD is not None:
        User = get_user_model()
        max_length = User._meta.get_field(USER_MODEL_USERNAME_FIELD).max_length
    else:
        max_length = 0
    return max_length

First approach: So you could change max_length value directly on your User's model username field if you have it swapped.

I don't think overriding form fields or __init__ method will actually work the it suggested by other answers, because assign of max_length happens in subclass of ACCOUNT_SIGNUP_FORM_CLASS https://github.com/pennersr/django-allauth/blob/330bf899dd77046fd0510221f3c12e69eb2bc64d/allauth/account/forms.py#L259

class BaseSignupForm(_base_signup_form_class()):

where _base_signup_form_class is function that gets your ACCOUNT_SIGNUP_FORM_CLASS

Second approach: is to subclass SignupView and override it's SignupForm read Override signup view django-allauth and How to customize user profile when using django-allauth

In that SignupForm you could actually do what @MehdiB or @PeterSobhi suggested.

ImproperlyConfigured issue occurs because of https://github.com/pennersr/django-allauth/issues/1792

So you be sure that these forms are defined in different python modules as per https://github.com/pennersr/django-allauth/issues/1749#issuecomment-304628013

# base/forms.py 
# this is form that your ACCOUNT_SIGNUP_FORM_CLASS is points to
class BaseSignupForm(forms.Form):

    captcha = ReCaptchaField(
        public_key=config("RECAPTCHA_PUBLIC_KEY"),
        private_key=config("RECAPTCHA_PRIVATE_KEY"),
    )

    class Meta:
        model = User

    def signup(self, request, user):
        """ Required, or else it throws deprecation warnings """
        pass

# data1/forms.py
# this is your signup form
from django.core.validators import MaxLengthValidator
from allauth.account.forms import SignupForm

class MySignupForm(SignupForm):
    def __init__(self, *args, **kwargs):
        super(MySignupForm, self).__init__(*args, **kwargs)
        self.fields['username']['validators'] += MaxLengthValidator(150, "Username should be less than 150 character long")

# views.py

from allauth.account.views import SignupView
class MySignupView(SignupView):
    form_class = MySignupForm

# urls.py

url(r"^signup/$", MySignupView.as_view(), name="account_signup"),