Fixed 2259 -- Made manually defined PKs readonly in admin inlines.

Jkhall81 · Jkhall81 · commit 262ca22cb6c1 · 2025-07-29T11:36:07.000-07:00
diff --git a/django/contrib/admin/options.py b/django/contrib/admin/options.py
@@ -414,27 +414,37 @@ def get_ordering(self, request):
         """
         return self.ordering or ()  # otherwise we might try to *None, which is bad ;)
 
-    def get_readonly_fields(self, request, obj=None):
+    def _get_readonly_manual_pk_fields(self, obj):
         """
-        Hook for specifying custom readonly fields.
+        Returns a list of primary key field names that should be readonly if:
+        - we're editing an existing object,
+        - the PK was manually defined (not auto-created),
+        - and it's not already in self.readonly_fields.
+        Supports both single and composite PKs.
         """
-        readonly = self.readonly_fields
-        pk_field = self.model._meta.pk
+        if not obj:
+            return []
+
+        readonly = []
+        # Supports forward compatibility with composite primary keys
+        pk_fields = self.model._meta.pk_fields
+
+        for pk in pk_fields:
+            if (
+                pk.editable
+                and not pk.auto_created
+                and pk.name not in self.readonly_fields
+            ):
+                readonly.append(pk.name)
 
-        # Only add PK to readonly if:
-        # - editing an existing object
-        # - PK is not auto-created
-        # - it's not already in the readonly list
-        # - and this is NOT an inline admin (which has `parent_model`)
-        if (
-            obj is not None
-            and not pk_field.auto_created
-            and pk_field.name not in readonly
-            and not hasattr(self, "parent_model")
-        ):
-            readonly = readonly + (pk_field.name,)
         return readonly
 
+    def get_readonly_fields(self, request, obj=None):
+        """
+        Hook for specifying custom readonly fields.
+        """
+        return list(self.readonly_fields) + self._get_readonly_manual_pk_fields(obj)
+
     def get_prepopulated_fields(self, request, obj=None):
         """
         Hook for specifying custom prepopulated fields.
diff --git a/django/contrib/admin/static/admin/css/base.css b/django/contrib/admin/static/admin/css/base.css
@@ -109,10 +109,6 @@ body {
     background: var(--body-bg);
 }
 
-label {
-    font-size: 1rem;
-}
-
 /* LINKS */
 
 a:link, a:visited {
diff --git a/tests/admin_inlines/tests.py b/tests/admin_inlines/tests.py
@@ -19,6 +19,7 @@
     Child,
     ChildModel1,
     ChildModel2,
+    EditablePKBook,
     ExtraTerrestrial,
     Fashionista,
     FootNote,
@@ -708,6 +709,21 @@ def test_inline_editable_pk(self):
             count=1,
         )
 
+    def test_inline_manual_pk_is_readonly_when_editing(self):
+        author = Author.objects.create(name="Jane Austen")
+        EditablePKBook.objects.create(
+            author=author, manual_pk=101, title="Pride and Prejudice"
+        )
+
+        response = self.client.get(
+            reverse("admin:admin_inlines_author_change", args=[author.pk])
+        )
+
+        self.assertContains(
+            response, 'name="editablepkbook_set-0-manual_pk"', html=False
+        )
+        self.assertContains(response, "readonly", html=False)
+
     def test_stacked_inline_edit_form_contains_has_original_class(self):
         holder = Holder.objects.create(dummy=1)
         holder.inner_set.create(dummy=1)

Original file line number	Diff line number	Diff line change
`@@ -109,10 +109,6 @@ body {`
`109`	`109`	`background: var(--body-bg);`
`110`	`110`	`}`
`111`	`111`
`112`		`-label {`
`113`		`- font-size: 1rem;`
`114`		`-}`
`115`		`-`
`116`	`112`	`/* LINKS */`
`117`	`113`
`118`	`114`	`a:link, a:visited {`