Plugin Development: Multiple Events/Webhooks triggered for the same request

[peteeckel]

The problem is not that easy to reproduce. I'm working on the netbox_dns plugin and users are seeing a problem that they get multiple events (and, as a consequence, webhook executions) when an object is created or updated. I was able to track it down to how m2m_changed events are handled by the handle_changed_object() function in netbox/extras/signals.

In my data model for DNS zones, there is a custom save() function that updates some other model instances after calling super().save(). This leads multiple invocations of handle_changed_object(), potentially queueing multiple object change events after the one for the zone object that is handled in the request. The zone object also has a many-to-many relationship with nameserver objects, so there is also potentially an m2m_changed event causing another invocation of handle_changed_object() for the zone. So far, so good.

The problem is now that the invocation of super().save() causes an event for the zone object to be enqueued, then some other events for other objects are enqueued, and then the m2m_changed signal is handled and another event for the zone object is queued. Looking at the code of handle_changed_object(), the interesting part is this:

    if m2m_changed and queue and is_same_object(instance, queue[-1], request.id):
        instance.refresh_from_db()  # Ensure that we're working with fresh M2M assignments
        queue[-1]['data'] = serialize_for_event(instance)
        queue[-1]['snapshots']['postchange'] = get_snapshots(instance, action)['postchange']
    else:
        enqueue_object(queue, instance, request.user, request.id, action)
    events_queue.set(queue)

What it should do is obviously to check for an existing event for the same object in the queue, and if there is one, update that event instead of queuing a new one.

The problem is now that after the original change or create event for the zone object, other events were queued as well, so queue[-1] is not the earlier event for the same object we are looking for. As a result, the enqueue_object() function is called, and so there are now two queue entries for the same object and the same request. This results in two webhook invocations, the first of which is obviously not getting correct data (the m2m fields are not updated yet).

[27] Wed, 06 Dec 2023 14:59:36 GMT 127.0.0.1 "POST / HTTP/1.1" 200 -
Host: localhost:9000
Accept-Encoding: identity
User-Agent: python-urllib3/2.1.0
Content-Type: application/json
Content-Length: 2731

{
    "event": "updated",
    "timestamp": "2023-12-06T14:59:35.998869+00:00",
    "model": "zone",
    "username": "admin",
    "request_id": "2e93a69c-54e0-47c4-8f64-3535ab191e04",
    "data": {
        "id": 1,
        "url": "/api/plugins/netbox-dns/zones/1/",
        "name": "zone1.example.com",
        "view": null,
        "display": "zone1.example.com",
        "nameservers": [
            {
                "id": 1,
                "url": "/api/plugins/netbox-dns/nameservers/1/",
                "display": "ns1.example.com",
                "name": "ns1.example.com"
            },
            {
                "id": 2,
                "url": "/api/plugins/netbox-dns/nameservers/2/",
                "display": "ns2.example.com",
                "name": "ns2.example.com"
            }
        ],
        "status": "active",
        "description": "",
        "tags": [
            {
                "id": 1,
                "url": "/api/extras/tags/1/",
                "display": "TEST1",
                "name": "TEST1",
                "slug": "test1",
                "color": "9e9e9e"
            },
            {
                "id": 2,
                "url": "/api/extras/tags/2/",
                "display": "TEST2",
                "name": "TEST2",
                "slug": "test2",
                "color": "9e9e9e"
            }
        ],
        "created": "2023-12-05T18:16:25.314125Z",
        "last_updated": "2023-12-06T14:59:35.840836Z",
        "default_ttl": 86400,
        "soa_ttl": 86400,
        "soa_mname": {
            "id": 2,
            "url": "/api/plugins/netbox-dns/nameservers/2/",
            "display": "ns2.example.com",
            "name": "ns2.example.com"
        },
        "soa_rname": "hostmaster.example.com",
        "soa_serial": 1701874683,
        "soa_serial_auto": true,
        "soa_refresh": 172800,
        "soa_retry": 7201,
        "soa_expire": 2592000,
        "soa_minimum": 3600,
        "registrar": null,
        "registry_domain_id": null,
        "registrant": null,
        "tech_c": null,
        "admin_c": null,
        "billing_c": null,
        "active": true,
        "custom_fields": {},
        "tenant": null
    },
    "snapshots": {
        "prechange": {
            "created": "2023-12-05T18:16:25.314Z",
            "last_updated": "2023-12-06T14:58:02.773Z",
            "view": null,
            "name": "zone1.example.com",
            "status": "active",
            "default_ttl": 86400,
            "soa_ttl": 86400,
            "soa_mname": 2,
            "soa_rname": "hostmaster.example.com",
            "soa_serial": 1701874392,
            "soa_refresh": 172800,
            "soa_retry": 7201,
            "soa_expire": 2592000,
            "soa_minimum": 3600,
            "soa_serial_auto": true,
            "description": "",
            "arpa_network": null,
            "tenant": null,
            "registrar": null,
            "registry_domain_id": null,
            "registrant": null,
            "admin_c": null,
            "tech_c": null,
            "billing_c": null,
            "nameservers": [
                1,
                2
            ],
            "custom_fields": {},
            "tags": [
                "TEST1",
                "TEST2"
            ]
        },
        "postchange": {
            "created": "2023-12-05T18:16:25.314Z",
            "last_updated": "2023-12-06T14:59:35.840Z",
            "view": null,
            "name": "zone1.example.com",
            "status": "active",
            "default_ttl": 86400,
            "soa_ttl": 86400,
            "soa_mname": 2,
            "soa_rname": "hostmaster.example.com",
            "soa_serial": 1701874683,
            "soa_refresh": 172800,
            "soa_retry": 7201,
            "soa_expire": 2592000,
            "soa_minimum": 3600,
            "soa_serial_auto": true,
            "description": "",
            "arpa_network": null,
            "tenant": null,
            "registrar": null,
            "registry_domain_id": null,
            "registrant": null,
            "admin_c": null,
            "tech_c": null,
            "billing_c": null,
            "nameservers": [
                1,
                2
            ],
            "custom_fields": {},
            "tags": [
                "TEST1",
                "TEST2"
            ]
        }
    }
}
Completed request #27
------------
[28] Wed, 06 Dec 2023 14:59:36 GMT 127.0.0.1 "POST / HTTP/1.1" 200 -
Host: localhost:9000
Accept-Encoding: identity
User-Agent: python-urllib3/2.1.0
Content-Type: application/json
Content-Length: 2611

{
    "event": "updated",
    "timestamp": "2023-12-06T14:59:36.010663+00:00",
    "model": "zone",
    "username": "admin",
    "request_id": "2e93a69c-54e0-47c4-8f64-3535ab191e04",
    "data": {
        "id": 1,
        "url": "/api/plugins/netbox-dns/zones/1/",
        "name": "zone1.example.com",
        "view": null,
        "display": "zone1.example.com",
        "nameservers": [
            {
                "id": 1,
                "url": "/api/plugins/netbox-dns/nameservers/1/",
                "display": "ns1.example.com",
                "name": "ns1.example.com"
            }
        ],
        "status": "active",
        "description": "",
        "tags": [
            {
                "id": 1,
                "url": "/api/extras/tags/1/",
                "display": "TEST1",
                "name": "TEST1",
                "slug": "test1",
                "color": "9e9e9e"
            },
            {
                "id": 2,
                "url": "/api/extras/tags/2/",
                "display": "TEST2",
                "name": "TEST2",
                "slug": "test2",
                "color": "9e9e9e"
            }
        ],
        "created": "2023-12-05T18:16:25.314125Z",
        "last_updated": "2023-12-06T14:59:35.840836Z",
        "default_ttl": 86400,
        "soa_ttl": 86400,
        "soa_mname": {
            "id": 2,
            "url": "/api/plugins/netbox-dns/nameservers/2/",
            "display": "ns2.example.com",
            "name": "ns2.example.com"
        },
        "soa_rname": "hostmaster.example.com",
        "soa_serial": 1701874683,
        "soa_serial_auto": true,
        "soa_refresh": 172800,
        "soa_retry": 7201,
        "soa_expire": 2592000,
        "soa_minimum": 3600,
        "registrar": null,
        "registry_domain_id": null,
        "registrant": null,
        "tech_c": null,
        "admin_c": null,
        "billing_c": null,
        "active": true,
        "custom_fields": {},
        "tenant": null
    },
    "snapshots": {
        "prechange": {
            "created": "2023-12-05T18:16:25.314Z",
            "last_updated": "2023-12-06T14:58:02.773Z",
            "view": null,
            "name": "zone1.example.com",
            "status": "active",
            "default_ttl": 86400,
            "soa_ttl": 86400,
            "soa_mname": 2,
            "soa_rname": "hostmaster.example.com",
            "soa_serial": 1701874392,
            "soa_refresh": 172800,
            "soa_retry": 7201,
            "soa_expire": 2592000,
            "soa_minimum": 3600,
            "soa_serial_auto": true,
            "description": "",
            "arpa_network": null,
            "tenant": null,
            "registrar": null,
            "registry_domain_id": null,
            "registrant": null,
            "admin_c": null,
            "tech_c": null,
            "billing_c": null,
            "nameservers": [
                1,
                2
            ],
            "custom_fields": {},
            "tags": [
                "TEST1",
                "TEST2"
            ]
        },
        "postchange": {
            "created": "2023-12-05T18:16:25.314Z",
            "last_updated": "2023-12-06T14:59:35.840Z",
            "view": null,
            "name": "zone1.example.com",
            "status": "active",
            "default_ttl": 86400,
            "soa_ttl": 86400,
            "soa_mname": 2,
            "soa_rname": "hostmaster.example.com",
            "soa_serial": 1701874683,
            "soa_refresh": 172800,
            "soa_retry": 7201,
            "soa_expire": 2592000,
            "soa_minimum": 3600,
            "soa_serial_auto": true,
            "description": "",
            "arpa_network": null,
            "tenant": null,
            "registrar": null,
            "registry_domain_id": null,
            "registrant": null,
            "admin_c": null,
            "tech_c": null,
            "billing_c": null,
            "nameservers": [
                1
            ],
            "custom_fields": {},
            "tags": [
                "TEST1",
                "TEST2"
            ]
        }
    }
}
Completed request #28
------------

I'm pretty sure this is not limited to this specific case, but I'm not sure how to proceed from here. Depending on the logic that determines when the queue is actually worked on, an idea might be to replace the queue[-1] approach with some smarter logic that finds all queue entries with the same instance ID and request in the queue and then using the last one.

[peteeckel]

I created an experimental patch that solves this issue for me. Did not run the NetBox test suite so far.

The basic idea is not to use the queue entry immediately before the last one and check whether it matches the object and request, but to find the last queue entry matching the object and request (if any) and updating that one.

diff --git a/netbox/extras/signals.py b/netbox/extras/signals.py
index 42204f86e..cb6850eff 100644
--- a/netbox/extras/signals.py
+++ b/netbox/extras/signals.py
@@ -29,18 +29,6 @@ from .models import CustomField, ObjectChange, TaggedItem
 clear_events = Signal()
 
 
-def is_same_object(instance, webhook_data, request_id):
-    """
-    Compare the given instance to the most recent queued webhook object, returning True
-    if they match. This check is used to avoid creating duplicate webhook entries.
-    """
-    return (
-        ContentType.objects.get_for_model(instance) == webhook_data['content_type'] and
-        instance.pk == webhook_data['object_id'] and
-        request_id == webhook_data['request_id']
-    )
-
-
 @receiver((post_save, m2m_changed))
 def handle_changed_object(sender, instance, **kwargs):
     """
@@ -86,10 +74,19 @@ def handle_changed_object(sender, instance, **kwargs):
 
     # If this is an M2M change, update the previously queued webhook (from post_save)
     queue = events_queue.get()
-    if m2m_changed and queue and is_same_object(instance, queue[-1], request.id):
+
+    # Find all indices of events in the queue that match the current instance in request id, content
+    # type and object id
+    indices = [index for index, event in enumerate(queue)
+               if event['request_id'] == request.id
+               and event['content_type'] == ContentType.objects.get_for_model(instance)
+               and event['object_id'] == instance.pk]
+
+    if m2m_changed and indices:
         instance.refresh_from_db()  # Ensure that we're working with fresh M2M assignments
-        queue[-1]['data'] = serialize_for_event(instance)
-        queue[-1]['snapshots']['postchange'] = get_snapshots(instance, action)['postchange']
+        last_index = max(indices)
+        queue[last_index]['data'] = serialize_for_event(instance)
+        queue[last_index]['snapshots']['postchange'] = get_snapshots(instance, action)['postchange']
     else:
         enqueue_object(queue, instance, request.user, request.id, action)
     events_queue.set(queue)

[peteeckel]

I found the time to run the NetBox tests now.

Reference run without the above patch:

(netbox) [root@dns netbox]# ./manage.py test extras.tests.test_event_rules -v2 --keepdb
Found 8 test(s).
Using existing test database for alias 'default' ('test_netbox')...
Operations to perform:
  Synchronize unmigrated apps: corsheaders, debug_toolbar, django_filters, django_prometheus, django_tables2, drf_spectacular, drf_spectacular_sidecar, forms, graphene_django, graphiql_debug_toolbar, humanize, messages, mptt, rest_framework, staticfiles, timezone_field, utilities
  Apply all migrations: account, admin, auth, circuits, contenttypes, core, dcim, django_rq, dummy_plugin, extras, ipam, sessions, social_django, taggit, tenancy, users, virtualization, vpn, wireless
Synchronizing apps without migrations:
  Creating tables...
    Running deferred SQL...
Running migrations:
  No migrations to apply.
  Your models in app(s): 'dummy_plugin' have changes that are not yet reflected in a migration, and so won't be applied.
  Run 'manage.py makemigrations' to make new migrations, and then re-run 'manage.py migrate' to apply them.
System check identified no issues (0 silenced).
test_bulk_create_process_eventrule (extras.tests.test_event_rules.EventRuleTest.test_bulk_create_process_eventrule)
Check that bulk creating multiple objects with an applicable EventRule queues a background task for each ... FAIL
test_bulk_delete_process_eventrule (extras.tests.test_event_rules.EventRuleTest.test_bulk_delete_process_eventrule)
Check that bulk deleting multiple objects with an applicable EventRule queues a background task for each ... FAIL
test_bulk_update_process_eventrule (extras.tests.test_event_rules.EventRuleTest.test_bulk_update_process_eventrule)
Check that bulk updating multiple objects with an applicable EventRule queues a background task for each ... FAIL
test_eventrule_conditions (extras.tests.test_event_rules.EventRuleTest.test_eventrule_conditions)
Test evaluation of EventRule conditions. ... ok
test_send_webhook (extras.tests.test_event_rules.EventRuleTest.test_send_webhook) ... ERROR
test_single_create_process_eventrule (extras.tests.test_event_rules.EventRuleTest.test_single_create_process_eventrule)
Check that creating an object with an applicable EventRule queues a background task for the rule's action. ... FAIL
test_single_delete_process_eventrule (extras.tests.test_event_rules.EventRuleTest.test_single_delete_process_eventrule)
Check that deleting an object with an applicable EventRule queues a background task for the rule's action. ... FAIL
test_single_update_process_eventrule (extras.tests.test_event_rules.EventRuleTest.test_single_update_process_eventrule)
Check that updating an object with an applicable EventRule queues a background task for the rule's action. ... FAIL

======================================================================
ERROR: test_send_webhook (extras.tests.test_event_rules.EventRuleTest.test_send_webhook)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/opt/netbox/netbox/extras/tests/test_event_rules.py", line 374, in test_send_webhook
    job = self.queue.jobs[0]
          ~~~~~~~~~~~~~~~^^^
IndexError: list index out of range

======================================================================
FAIL: test_bulk_create_process_eventrule (extras.tests.test_event_rules.EventRuleTest.test_bulk_create_process_eventrule)
Check that bulk creating multiple objects with an applicable EventRule queues a background task for each
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/opt/netbox/netbox/extras/tests/test_event_rules.py", line 178, in test_bulk_create_process_eventrule
    self.assertEqual(self.queue.count, 3)
AssertionError: 2 != 3

======================================================================
FAIL: test_bulk_delete_process_eventrule (extras.tests.test_event_rules.EventRuleTest.test_bulk_delete_process_eventrule)
Check that bulk deleting multiple objects with an applicable EventRule queues a background task for each
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/opt/netbox/netbox/extras/tests/test_event_rules.py", line 324, in test_bulk_delete_process_eventrule
    self.assertEqual(self.queue.count, 3)
AssertionError: 2 != 3

======================================================================
FAIL: test_bulk_update_process_eventrule (extras.tests.test_event_rules.EventRuleTest.test_bulk_update_process_eventrule)
Check that bulk updating multiple objects with an applicable EventRule queues a background task for each
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/opt/netbox/netbox/extras/tests/test_event_rules.py", line 265, in test_bulk_update_process_eventrule
    self.assertEqual(self.queue.count, 3)
AssertionError: 2 != 3

======================================================================
FAIL: test_single_create_process_eventrule (extras.tests.test_event_rules.EventRuleTest.test_single_create_process_eventrule)
Check that creating an object with an applicable EventRule queues a background task for the rule's action.
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/opt/netbox/netbox/extras/tests/test_event_rules.py", line 128, in test_single_create_process_eventrule
    self.assertEqual(self.queue.count, 1)
AssertionError: 0 != 1

======================================================================
FAIL: test_single_delete_process_eventrule (extras.tests.test_event_rules.EventRuleTest.test_single_delete_process_eventrule)
Check that deleting an object with an applicable EventRule queues a background task for the rule's action.
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/opt/netbox/netbox/extras/tests/test_event_rules.py", line 291, in test_single_delete_process_eventrule
    self.assertEqual(self.queue.count, 1)
AssertionError: 0 != 1

======================================================================
FAIL: test_single_update_process_eventrule (extras.tests.test_event_rules.EventRuleTest.test_single_update_process_eventrule)
Check that updating an object with an applicable EventRule queues a background task for the rule's action.
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/opt/netbox/netbox/extras/tests/test_event_rules.py", line 209, in test_single_update_process_eventrule
    self.assertEqual(self.queue.count, 1)
AssertionError: 0 != 1

----------------------------------------------------------------------
Ran 8 tests in 1.040s

FAILED (failures=6, errors=1)
Preserving test database for alias 'default' ('test_netbox')...

(all other tests pass)

Test run with the patch:

(netbox) [root@dns netbox]# ./manage.py test extras.tests.test_event_rules -v2 --keepdb
Found 8 test(s).
Using existing test database for alias 'default' ('test_netbox')...
Operations to perform:
  Synchronize unmigrated apps: corsheaders, debug_toolbar, django_filters, django_prometheus, django_tables2, drf_spectacular, drf_spectacular_sidecar, forms, graphene_django, graphiql_debug_toolbar, humanize, messages, mptt, rest_framework, staticfiles, timezone_field, utilities
  Apply all migrations: account, admin, auth, circuits, contenttypes, core, dcim, django_rq, dummy_plugin, extras, ipam, sessions, social_django, taggit, tenancy, users, virtualization, vpn, wireless
Synchronizing apps without migrations:
  Creating tables...
    Running deferred SQL...
Running migrations:
  No migrations to apply.
  Your models in app(s): 'dummy_plugin' have changes that are not yet reflected in a migration, and so won't be applied.
  Run 'manage.py makemigrations' to make new migrations, and then re-run 'manage.py migrate' to apply them.
System check identified no issues (0 silenced).
test_bulk_create_process_eventrule (extras.tests.test_event_rules.EventRuleTest.test_bulk_create_process_eventrule)
Check that bulk creating multiple objects with an applicable EventRule queues a background task for each ... FAIL
test_bulk_delete_process_eventrule (extras.tests.test_event_rules.EventRuleTest.test_bulk_delete_process_eventrule)
Check that bulk deleting multiple objects with an applicable EventRule queues a background task for each ... FAIL
test_bulk_update_process_eventrule (extras.tests.test_event_rules.EventRuleTest.test_bulk_update_process_eventrule)
Check that bulk updating multiple objects with an applicable EventRule queues a background task for each ... FAIL
test_eventrule_conditions (extras.tests.test_event_rules.EventRuleTest.test_eventrule_conditions)
Test evaluation of EventRule conditions. ... ok
test_send_webhook (extras.tests.test_event_rules.EventRuleTest.test_send_webhook) ... ERROR
test_single_create_process_eventrule (extras.tests.test_event_rules.EventRuleTest.test_single_create_process_eventrule)
Check that creating an object with an applicable EventRule queues a background task for the rule's action. ... FAIL
test_single_delete_process_eventrule (extras.tests.test_event_rules.EventRuleTest.test_single_delete_process_eventrule)
Check that deleting an object with an applicable EventRule queues a background task for the rule's action. ... FAIL
test_single_update_process_eventrule (extras.tests.test_event_rules.EventRuleTest.test_single_update_process_eventrule)
Check that updating an object with an applicable EventRule queues a background task for the rule's action. ... FAIL

======================================================================
ERROR: test_send_webhook (extras.tests.test_event_rules.EventRuleTest.test_send_webhook)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/opt/netbox/netbox/extras/tests/test_event_rules.py", line 374, in test_send_webhook
    job = self.queue.jobs[0]
          ~~~~~~~~~~~~~~~^^^
IndexError: list index out of range

======================================================================
FAIL: test_bulk_create_process_eventrule (extras.tests.test_event_rules.EventRuleTest.test_bulk_create_process_eventrule)
Check that bulk creating multiple objects with an applicable EventRule queues a background task for each
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/opt/netbox/netbox/extras/tests/test_event_rules.py", line 178, in test_bulk_create_process_eventrule
    self.assertEqual(self.queue.count, 3)
AssertionError: 2 != 3

======================================================================
FAIL: test_bulk_delete_process_eventrule (extras.tests.test_event_rules.EventRuleTest.test_bulk_delete_process_eventrule)
Check that bulk deleting multiple objects with an applicable EventRule queues a background task for each
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/opt/netbox/netbox/extras/tests/test_event_rules.py", line 324, in test_bulk_delete_process_eventrule
    self.assertEqual(self.queue.count, 3)
AssertionError: 2 != 3

======================================================================
FAIL: test_bulk_update_process_eventrule (extras.tests.test_event_rules.EventRuleTest.test_bulk_update_process_eventrule)
Check that bulk updating multiple objects with an applicable EventRule queues a background task for each
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/opt/netbox/netbox/extras/tests/test_event_rules.py", line 265, in test_bulk_update_process_eventrule
    self.assertEqual(self.queue.count, 3)
AssertionError: 2 != 3

======================================================================
FAIL: test_single_create_process_eventrule (extras.tests.test_event_rules.EventRuleTest.test_single_create_process_eventrule)
Check that creating an object with an applicable EventRule queues a background task for the rule's action.
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/opt/netbox/netbox/extras/tests/test_event_rules.py", line 128, in test_single_create_process_eventrule
    self.assertEqual(self.queue.count, 1)
AssertionError: 0 != 1

======================================================================
FAIL: test_single_delete_process_eventrule (extras.tests.test_event_rules.EventRuleTest.test_single_delete_process_eventrule)
Check that deleting an object with an applicable EventRule queues a background task for the rule's action.
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/opt/netbox/netbox/extras/tests/test_event_rules.py", line 291, in test_single_delete_process_eventrule
    self.assertEqual(self.queue.count, 1)
AssertionError: 0 != 1

======================================================================
FAIL: test_single_update_process_eventrule (extras.tests.test_event_rules.EventRuleTest.test_single_update_process_eventrule)
Check that updating an object with an applicable EventRule queues a background task for the rule's action.
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/opt/netbox/netbox/extras/tests/test_event_rules.py", line 209, in test_single_update_process_eventrule
    self.assertEqual(self.queue.count, 1)
AssertionError: 0 != 1

----------------------------------------------------------------------
Ran 8 tests in 1.012s

FAILED (failures=6, errors=1)
Preserving test database for alias 'default' ('test_netbox')...

(all other tests pass)

In summary: 6 Tests are failing and one is erroring out, but they are behaving in exactly the same way whether the patch is in place or not.

While this is not a totally valid test, it at least seems that the patch does not change the behaviour of NetBox in any way. As soon as I manage to get a successful test without the patch I'll know more.

[peteeckel]

Update: This is related to #6284.

The fix for this issue only works if the m2m_changed signal is received immediately after the post_save signal. This is, however, not necessarily the case, depending on the functionality of the save() method.

[peteeckel]

And another update: I created issue #15194 for it, and I have a prepared PR in my drawer.