Fix vote delegation update error

docker/docker-compose.dev.yml

@@ -19,6 +19,8 @@ services:
     depends_on:
       - redis
       - postgres
+    stdin_open: true
+    tty: true
 
   postgres:
     image: postgres:11

server/openslides/users/views.py

@@ -167,6 +167,11 @@ class UserViewSet(ModelViewSet):
         ):
             request.data["username"] = user.username
 
+        # handle delegated_from field seperately since its a SerializerMethodField
+        new_delegation_ids = request.data.get("vote_delegated_from_users_id")
+        if "vote_delegated_from_users_id" in request.data:
+            del request.data["vote_delegated_from_users_id"]
+
         # check that no chains are created with vote delegation
         delegate_id = request.data.get("vote_delegated_to_id")
         if delegate_id:
@@ -181,16 +186,15 @@ class UserViewSet(ModelViewSet):
 
             self.assert_no_self_delegation(user, [delegate_id])
             self.assert_vote_not_delegated(delegate)
+            # if vote_delegated_from is reset in this request, we can skip this check
+            if new_delegation_ids != []:
                 self.assert_has_no_delegated_votes(user)
 
             inform_changed_data(delegate)
             if user.vote_delegated_to:
                 inform_changed_data(user.vote_delegated_to)
-
+        elif "vote_delegated_to_id" in request.data and user.vote_delegated_to:
-        # handle delegated_from field seperately since its a SerializerMethodField
+            inform_changed_data(user.vote_delegated_to)
-        new_delegation_ids = request.data.get("vote_delegated_from_users_id")
-        if "vote_delegated_from_users_id" in request.data:
-            del request.data["vote_delegated_from_users_id"]
 
         try:
             response = super().update(request, *args, **kwargs)
@@ -199,7 +203,9 @@ class UserViewSet(ModelViewSet):
 
         # after rest of the request succeeded, handle delegation changes
         if isinstance(new_delegation_ids, list):
+            user.refresh_from_db()  # fetch updated model
             self.assert_no_self_delegation(user, new_delegation_ids)
+            if new_delegation_ids:
                 self.assert_vote_not_delegated(user)
 
             for id in new_delegation_ids:

server/tests/integration/users/test_viewset.py

@@ -217,6 +217,40 @@ class UserUpdate(TestCase):
             [user.pk],
         )
 
+    def test_update_vote_delegation_same_user(self):
+        user = User.objects.create_user(
+            username="non-admin EVnE4n103fPZXcVV",
+            password="non-admin 1WywRnqKbcdtQwS2",
+            vote_delegated_to=self.admin,
+        )
+
+        response = self.client.patch(
+            reverse("user-detail", args=[user.pk]),
+            {"vote_delegated_to_id": self.admin.pk, "vote_delegated_from_users_id": []},
+        )
+
+        self.assertEqual(response.status_code, status.HTTP_200_OK)
+        user = User.objects.get(pk=user.pk)
+        self.assertEqual(user.vote_delegated_to_id, self.admin.pk)
+
+    def test_update_remove_vote_delegation(self):
+        user = User.objects.create_user(
+            username="non-admin EVnE4n103fPZXcVV",
+            password="non-admin 1WywRnqKbcdtQwS2",
+            vote_delegated_to=self.admin,
+        )
+
+        response = self.client.patch(
+            reverse("user-detail", args=[user.pk]),
+            {"vote_delegated_to_id": None, "vote_delegated_from_users_id": []},
+        )
+
+        self.assertEqual(response.status_code, status.HTTP_200_OK)
+        user = User.objects.get(pk=user.pk)
+        self.assertEqual(user.vote_delegated_to_id, None)
+        admin = User.objects.get(username="admin")
+        self.assertEqual(admin.vote_delegated_from_users.count(), 0)
+
     def test_update_vote_delegation_non_admin(self):
         user = User.objects.create_user(
             username="non-admin WpBQRSsCg6qNWNtN6bLP",
@@ -380,6 +414,68 @@ class UserUpdate(TestCase):
         user2 = User.objects.get(pk=self.user2.pk)
         self.assertIsNone(user2.vote_delegated_to_id)
 
+    def test_update_vote_delegation_both_1(self):
+        """ Change user -> user2 to admin -> user in one request. """
+        self.user2 = User.objects.create_user(
+            username="user2",
+            password="non-admin 1WywRnqKbcdtQwS2",
+        )
+        self.user = User.objects.create_user(
+            username="user",
+            password="non-admin 1WywRnqKbcdtQwS2",
+            vote_delegated_to=self.user2,
+        )
+        response = self.client.patch(
+            reverse("user-detail", args=[self.user.pk]),
+            {
+                "vote_delegated_to_id": None,
+                "vote_delegated_from_users_id": [self.admin.pk],
+            },
+        )
+
+        self.assertHttpStatusVerbose(response, status.HTTP_200_OK)
+        admin = User.objects.get(pk=self.admin.pk)
+        self.assertEqual(admin.vote_delegated_to_id, self.user.id)
+        user = User.objects.get(pk=self.user.pk)
+        self.assertIsNone(user.vote_delegated_to_id)
+        self.assertEqual(
+            list(user.vote_delegated_from_users.values_list("id", flat=True)),
+            [self.admin.pk],
+        )
+        user2 = User.objects.get(pk=self.user2.pk)
+        self.assertEqual(user2.vote_delegated_from_users.count(), 0)
+
+    def test_update_vote_delegation_both_2(self):
+        """ Change user -> user2 to user2 -> admin in one request. """
+        self.user2 = User.objects.create_user(
+            username="user2",
+            password="non-admin 1WywRnqKbcdtQwS2",
+        )
+        self.user = User.objects.create_user(
+            username="user",
+            password="non-admin 1WywRnqKbcdtQwS2",
+            vote_delegated_to=self.user2,
+        )
+        response = self.client.patch(
+            reverse("user-detail", args=[self.user2.pk]),
+            {
+                "vote_delegated_to_id": self.admin.pk,
+                "vote_delegated_from_users_id": [],
+            },
+        )
+
+        self.assertHttpStatusVerbose(response, status.HTTP_200_OK)
+        admin = User.objects.get(pk=self.admin.pk)
+        self.assertEqual(
+            list(admin.vote_delegated_from_users.values_list("id", flat=True)),
+            [self.user2.pk],
+        )
+        user = User.objects.get(pk=self.user.pk)
+        self.assertIsNone(user.vote_delegated_to_id)
+        user2 = User.objects.get(pk=self.user2.pk)
+        self.assertEqual(user2.vote_delegated_to, self.admin)
+        self.assertEqual(user2.vote_delegated_from_users.count(), 0)
+
 
 class UserDelete(TestCase):
     """