Fixed #35056 -- Fixed system check crash on reverse m2m relations with related_name in ModelAdmin.filter_horizontal/vertical.

felixxm · web-flow · commit 751d732a3815 · 2023-12-27T20:36:22.000+01:00
Thanks Thomas Feldmann for the report. Regression in 1078657.
diff --git a/django/contrib/admin/checks.py b/django/contrib/admin/checks.py
@@ -532,7 +532,7 @@ def _check_filter_item(self, obj, field_name, label):
                 field=field_name, option=label, obj=obj, id="admin.E019"
             )
         else:
-            if not field.many_to_many:
+            if not field.many_to_many or isinstance(field, models.ManyToManyRel):
                 return must_be(
                     "a many-to-many field", option=label, obj=obj, id="admin.E020"
                 )
diff --git a/docs/releases/5.0.1.txt b/docs/releases/5.0.1.txt
@@ -32,3 +32,7 @@ Bugfixes
 
 * Fixed a regression in Django 5.0 where querysets referenced incorrect field
   names from ``FilteredRelation()`` (:ticket:`35050`).
+
+* Fixed a regression in Django 5.0 that caused a system check crash when
+  ``ModelAdmin.filter_horizontal`` or ``filter_vertical`` contained a reverse
+  many-to-many relation with ``related_name`` (:ticket:`35056`).
diff --git a/tests/modeladmin/test_checks.py b/tests/modeladmin/test_checks.py
@@ -322,6 +322,24 @@ class TestModelAdmin(ModelAdmin):
             "admin.E020",
         )
 
+    @isolate_apps("modeladmin")
+    def test_invalid_reverse_m2m_field_with_related_name(self):
+        class Contact(Model):
+            pass
+
+        class Customer(Model):
+            contacts = ManyToManyField("Contact", related_name="customers")
+
+        class TestModelAdmin(ModelAdmin):
+            filter_vertical = ["customers"]
+
+        self.assertIsInvalid(
+            TestModelAdmin,
+            Contact,
+            "The value of 'filter_vertical[0]' must be a many-to-many field.",
+            "admin.E020",
+        )
+
     @isolate_apps("modeladmin")
     def test_invalid_m2m_field_with_through(self):
         class Artist(Model):
@@ -384,6 +402,24 @@ class TestModelAdmin(ModelAdmin):
             "admin.E020",
         )
 
+    @isolate_apps("modeladmin")
+    def test_invalid_reverse_m2m_field_with_related_name(self):
+        class Contact(Model):
+            pass
+
+        class Customer(Model):
+            contacts = ManyToManyField("Contact", related_name="customers")
+
+        class TestModelAdmin(ModelAdmin):
+            filter_horizontal = ["customers"]
+
+        self.assertIsInvalid(
+            TestModelAdmin,
+            Contact,
+            "The value of 'filter_horizontal[0]' must be a many-to-many field.",
+            "admin.E020",
+        )
+
     @isolate_apps("modeladmin")
     def test_invalid_m2m_field_with_through(self):
         class Artist(Model):

Original file line number	Diff line number	Diff line change
`@@ -532,7 +532,7 @@ def _check_filter_item(self, obj, field_name, label):`
`532`	`532`	`field=field_name, option=label, obj=obj, id="admin.E019"`
`533`	`533`	`)`
`534`	`534`	`else:`
`535`		`- if not field.many_to_many:`
	`535`	`+ if not field.many_to_many or isinstance(field, models.ManyToManyRel):`
`536`	`536`	`return must_be(`
`537`	`537`	`"a many-to-many field", option=label, obj=obj, id="admin.E020"`
`538`	`538`	`)`