Use IMPORT_STRINGS for auth rule (jazzband#336)

* Applied lint

Co-authored-by: Andrew-Chen-Wang <acwangpython@gmail.com>
Co-authored-by: David Sanders <davesque@gmail.com>

Author: davesque

rest_framework_simplejwt/serializers.py

@@ -1,5 +1,3 @@
-import importlib
-
 from django.contrib.auth import authenticate, get_user_model
 from django.contrib.auth.models import update_last_login
 from django.utils.translation import gettext_lazy as _
@@ -8,9 +6,6 @@
 from .settings import api_settings
 from .tokens import RefreshToken, SlidingToken, UntypedToken
 
-rule_package, user_eligible_for_login = api_settings.USER_AUTHENTICATION_RULE.rsplit('.', 1)
-login_rule = importlib.import_module(rule_package)
-
 
 class PasswordField(serializers.CharField):
     def __init__(self, *args, **kwargs):
@@ -47,7 +42,7 @@ def validate(self, attrs):
 
         self.user = authenticate(**authenticate_kwargs)
 
-        if not getattr(login_rule, user_eligible_for_login)(self.user):
+        if not api_settings.USER_AUTHENTICATION_RULE(self.user):
             raise exceptions.AuthenticationFailed(
                 self.error_messages['no_active_account'],
                 'no_active_account',

rest_framework_simplejwt/settings.py

@@ -42,6 +42,7 @@
 IMPORT_STRINGS = (
     'AUTH_TOKEN_CLASSES',
     'TOKEN_USER_CLASS',
+    'USER_AUTHENTICATION_RULE',
 )
 
 REMOVED_SETTINGS = (