Add ability to check if multiple fields are unique

README.md

@@ -40,7 +40,7 @@ OPENID_CONNECT_VIEWSET_CONFIG = {
         "preferred_username": "username",
     },
     "SPLIT_NAME_CLAIM": False, # Whether to split the `name` claim into first_name & last_name if present
-    "USER_UNIQUE_FILTER_FIELD": "username",
+    "USER_UNIQUE_FILTER_FIELDS": ["username", "email"],
     "USE_SSO_COOKIE": True,
     "SSO_COOKIE_DATA": "email",
     "SSO_COOKIE_MAX_AGE": None,

oidc/settings.py

@@ -13,7 +13,7 @@
     },
     "SPLIT_NAME_CLAIM": False,
     "USE_EMAIL_USERNAME": False,
-    "USER_UNIQUE_FILTER_FIELD": "username",
+    "USER_UNIQUE_FILTER_FIELDS": ["username", "email"],
     "SSO_COOKIE_DATA": "email",
     "JWT_ALGORITHM": "HS256",
     "FIELD_VALIDATION_REGEX": {

oidc/viewsets.py

@@ -82,9 +82,9 @@ def __init__(self, *args, **kwargs):
         self.auth_backend = config.get(
             "AUTH_BACKEND", "django.contrib.auth.backends.ModelBackend"
         )
-        self.unique_user_filter_field = (
-            config.get("USER_UNIQUE_FILTER_FIELD")
-            or default_config["USER_UNIQUE_FILTER_FIELD"]
+        self.unique_user_filter_fields = (
+            config.get("USER_UNIQUE_FILTER_FIELDS")
+            or default_config["USER_UNIQUE_FILTER_FIELDS"]
         )
         self.replaceable_username_characters = config.get(
             "REPLACE_USERNAME_CHARACTERS", default_config["REPLACE_USERNAME_CHARACTERS"]
@@ -130,18 +130,20 @@ def logout(self, request: HttpRequest, **kwargs: dict) -> HttpResponse:
             _("Unable to process OpenID connect logout request."),
         )
 
-    def _check_user_uniqueness(self, user_data: dict) -> bool:
+    def _check_user_uniqueness(self, user_data: dict) -> Optional[str]:
         """
         Helper function that checks if the supplied user data is unique. If user_data does not
         contain the unique user field the assumption is that the user
         exists.
         """
-        if user_data.get(self.unique_user_filter_field):
-            unique_field_value = user_data.get(self.unique_user_filter_field)
-            unique_field = self.unique_user_filter_field + "__iexact"
-            filter_kwargs = {unique_field: unique_field_value}
-            return not self.user_model.objects.filter(**filter_kwargs).count() > 0
-        return False
+        for user_field in self.unique_user_filter_fields:
+            if user_data.get(user_field):
+                unique_field_value = user_data.get(user_field)
+                unique_field = user_field + "__iexact"
+                filter_kwargs = {unique_field: unique_field_value}
+                if self.user_model.objects.filter(**filter_kwargs).count() > 0:
+                    return user_field
+        return None
 
     def generate_successful_response(
         self, request, user, redirect_after=None
@@ -334,14 +336,16 @@ def callback(self, request: HttpRequest, **kwargs: dict) -> HttpResponse:  # noq
                                     status=status.HTTP_400_BAD_REQUEST,
                                     template_name="oidc/oidc_unrecoverable_error.html",
                                 )
-                        elif not self._check_user_uniqueness(user_data):
-                            data = {
-                                "id_token": id_token,
-                                "error": f"{self.unique_user_filter_field.capitalize()} field is already in use.",
-                            }
-                            return Response(
-                                data, template_name="oidc/oidc_user_data_entry.html"
-                            )
+                        else:
+                            field = self._check_user_uniqueness(user_data)
+                            if field:
+                                data = {
+                                    "id_token": id_token,
+                                    "error": f"{field.capitalize()} field is already in use.",
+                                }
+                                return Response(
+                                    data, template_name="oidc/oidc_user_data_entry.html"
+                                )
 
                         self.validate_fields(user_data)
 

tests/test_viewsets.py

@@ -2,6 +2,8 @@
 Tests for the OpenID Client
 """
 
+import json
+
 from django.contrib.auth import get_user_model
 from django.test import TestCase
 from django.test.utils import override_settings
@@ -41,7 +43,7 @@
     },
     "SPLIT_NAME_CLAIM": True,
     "USE_EMAIL_USERNAME": True,
-    "USER_UNIQUE_FILTER_FIELD": "email",
+    "USER_UNIQUE_FILTER_FIELDS": ["email", "username"],
     "SSO_COOKIE_DATA": "email",
     "JWT_ALGORITHM": "HS256",
     "JWT_SECRET_KEY": "abc",
@@ -85,6 +87,83 @@ def test_returns_data_entry_template_on_missing_username_claim(self):
             self.assertEqual(response.status_code, 200)
             self.assertEqual(response.template_name, "oidc/oidc_user_data_entry.html")
 
+    @override_settings(OPENID_CONNECT_VIEWSET_CONFIG=OPENID_CONNECT_VIEWSET_CONFIG)
+    def test_recreating_already_existing_user(self):
+        """
+        Trying to create a user that already exists will ask you to chose a different username
+        """
+        view = UserModelOpenIDConnectViewset.as_view({"post": "callback"})
+        with patch(
+            "oidc.viewsets.OpenIDClient.verify_and_decode_id_token"
+        ) as mock_func:
+            mock_func.return_value = {
+                "family_name": "Frankline",
+                "given_name": "Benjamin",
+                "username": "bfrank",
+                "email": "[email protected]",
+            }
+
+            data = {"id_token": "sadsdaio3209lkasdlkas0d.sdojdsiad.iosdadia"}
+            request = self.factory.post("/", data=data)
+            response = view(request, auth_server="default")
+            # Creating the user for the first time will work ok
+            self.assertEqual(response.status_code, 302)
+            user = User.objects.get(username="bfrank")
+            self.assertEqual(user.email, "[email protected]")
+
+        with patch(
+            "oidc.viewsets.OpenIDClient.verify_and_decode_id_token"
+        ) as mock_func:
+            mock_func.return_value = {
+                "family_name": "Frankline",
+                "given_name": "Benjamin",
+                "username": "bfrank",
+                "email": "[email protected]",
+            }
+
+            data = {"id_token": "sadsdaio3209lkasdlkas0d.sdojdsiad.iosdadia"}
+            request = self.factory.post("/", data=data)
+            response = view(request, auth_server="default")
+            # Creating the user for the second time will not work ok
+            self.assertEqual(response.status_code, 200)
+
+            response_data = json.loads(response.rendered_content.decode("utf-8"))
+            self.assertEqual(
+                "Username field is already in use.", response_data["error"]
+            )
+            self.assertEqual(response.template_name, "oidc/oidc_user_data_entry.html")
+
+            # Original user with original email address still exists
+            user = User.objects.get(username="bfrank")
+            self.assertEqual(user.email, "[email protected]")
+
+        # Try creating the same user in uppercase
+        with patch(
+            "oidc.viewsets.OpenIDClient.verify_and_decode_id_token"
+        ) as mock_func:
+            mock_func.return_value = {
+                "family_name": "Frankline",
+                "given_name": "Benjamin",
+                "username": "BFRANK",
+                "email": "[email protected]",
+            }
+
+            data = {"id_token": "sadsdaio3209lkasdlkas0d.sdojdsiad.iosdadia"}
+            request = self.factory.post("/", data=data)
+            response = view(request, auth_server="default")
+            # Creating the user for the second time will not work ok
+            self.assertEqual(response.status_code, 200)
+
+            response_data = json.loads(response.rendered_content.decode("utf-8"))
+            self.assertEqual(
+                "Username field is already in use.", response_data["error"]
+            )
+            self.assertEqual(response.template_name, "oidc/oidc_user_data_entry.html")
+
+            # Original user with original email address still exists
+            user = User.objects.get(username="bfrank")
+            self.assertEqual(user.email, "[email protected]")
+
     @override_settings(OPENID_CONNECT_VIEWSET_CONFIG=OPENID_CONNECT_VIEWSET_CONFIG)
     def test_user_created_successfully_when_email_has_a_valid_username(self):
         """