Fixed #27356 -- Fixed ModelAdmin.lookup_allowed() for some nested relations.

tests/modeladmin/tests.py

@@ -8,8 +8,10 @@ from django.contrib.admin.options import (
 from django.contrib.admin.sites import AdminSite
 from django.contrib.admin.widgets import AdminDateWidget, AdminRadioSelect
 from django.contrib.auth.models import User
+from django.db import models
 from django.forms.widgets import Select
 from django.test import SimpleTestCase, TestCase
+from django.test.utils import isolate_apps
 
 from .models import Band, Concert
 
@@ -90,6 +92,33 @@ class ModelAdminTests(TestCase):
         ma = BandAdmin(Band, self.site)
         self.assertTrue(ma.lookup_allowed('name__nonexistent', 'test_value'))
 
+    @isolate_apps('modeladmin')
+    def test_lookup_allowed_onetoone(self):
+        class Department(models.Model):
+            code = models.CharField(max_length=4, unique=True)
+
+        class Employee(models.Model):
+            department = models.ForeignKey(Department, models.CASCADE, to_field="code")
+
+        class EmployeeProfile(models.Model):
+            employee = models.OneToOneField(Employee, models.CASCADE)
+
+        class EmployeeInfo(models.Model):
+            employee = models.OneToOneField(Employee, models.CASCADE)
+            description = models.CharField(max_length=100)
+
+        class EmployeeProfileAdmin(ModelAdmin):
+            list_filter = [
+                'employee__employeeinfo__description',
+                'employee__department__code',
+            ]
+
+        ma = EmployeeProfileAdmin(EmployeeProfile, self.site)
+        # Reverse OneToOneField
+        self.assertIs(ma.lookup_allowed('employee__employeeinfo__description', 'test_value'), True)
+        # OneToOneField and ForeignKey
+        self.assertIs(ma.lookup_allowed('employee__department__code', 'test_value'), True)
+
     def test_field_arguments(self):
         # If fields is specified, fieldsets_add and fieldsets_change should
         # just stick the fields into a formsets structure and return it.