Add 2fa authentication to dj_rest_auth login

settings.py

# in settings.py
REST_AUTH_SERIALIZERS = {
    # override dj_rest_auth serializer for 2fa
    'LOGIN_SERIALIZER': 'my_app.serializers.user.LoginSerializer'
}

user.py

# my_app.serializers.user
from dj_rest_auth.serializers import LoginSerializer as BaseLoginSerializer
from rest_framework import exceptions, serializers
from django_otp import match_token as match_otp_token
from django_otp import user_has_device as user_has_otp_device


class LoginSerializer(BaseLoginSerializer):
    """ Override dj_rest_auth LoginSerializer for 2fa tokens """
    otp_token = serializers.CharField(required=False, allow_blank=True)

    def validate(self, attrs):
        attrs = super().validate(attrs)
        user = attrs['user']
        if user_has_otp_device(user, confirmed=True):
            token = attrs.get('otp_token')
            if not token:
                attrs['user'] = None
                msg = _('Please provide a two factor code to authenticate.')
                raise exceptions.NotAcceptable({'otp_token': [msg]})
            if match_otp_token(user, token):
                return attrs
            else:
                attrs['user'] = None
                msg = _('Invalid two factor code.')
                raise exceptions.NotAuthenticated({'otp_token': [msg]})
        return attrs