Reverse lookups on OneToOneField not working?

[Willem Van Onsem]

This ​StackOverflow post shows a scenario where a OneToOneField is filtered on top of another OneToOneField. So for example with the following modeling:

class Switch(models.Model):
    fqdn = models.CharField(max_length=45, unique=True)

class ConfigState(models.Model):
    switch = models.OneToOneField(Switch, models.CASCADE, db_column='switch', primary_key=True,
                                  related_name='config_state')

class EdgeSwitch(models.Model):
    switch = models.OneToOneField(Switch, models.CASCADE, db_column='switch', primary_key=True,
                                      related_name='edge_switch')

The query EdgeSwitch.objects.filter(switch__config_state=1) does (no longer) work. On Django-3.x it apparently worked.

[Simon Charette]

I cannot reproduce the issue against main or stable/5.1.x with the following patch.

new file tests/ticket_36188/models.py

@@ +1 @@
+from django.db import models
+
+
+class Switch(models.Model):
+    fqdn = models.CharField(max_length=45, unique=True)
+
+
+class ConfigState(models.Model):
+    switch = models.OneToOneField(
+        Switch,
+        models.CASCADE,
+        db_column="switch",
+        primary_key=True,
+        related_name="config_state",
+    )
+
+
+class EdgeSwitch(models.Model):
+    switch = models.OneToOneField(
+        Switch,
+        models.CASCADE,
+        db_column="switch",
+        primary_key=True,
+        related_name="edge_switch",
+    )

new file tests/ticket_36188/tests.py

@@ +1 @@
+from django.test import TestCase
+
+from .models import EdgeSwitch
+
+
+class Ticket36188Tests(TestCase):
+    def test_reported_case(self):
+        list(EdgeSwitch.objects.filter(switch__config_state=1))
+        print(EdgeSwitch.objects.filter(switch__config_state=1).query)

Please re-open if you can provide a set of models that trigger a FieldError.

[willem-van-onsem]

I found the missing part: the Switch model needs to have managed = False. A bit curious that this has impact, so:

class Switch(models.Model):
    fqdn = models.CharField(max_length=45, unique=True)
    
    class Meta:
        managed = False

[willem-van-onsem]

I think I got it, the tables got an app_label, but that was probably not registered.