Fixed #13883 -- Rendered named choice groups with <optgroup> in FilteredSelectMultiple.

This patch adds support for <optgroup>s in FilteredSelectMultiple widgets.
When a popup returns a new object, if the source field contains optgroup
choices, the optgroup is now also included in the response data.

Additionally, this adds error handling for invalid source_model parameters
to prevent crashes and display user-friendly error messages instead.

Co-authored-by: Michael McLarnon <mmclar@gmail.com>

1 files changed, 121 insertions, 1 deletions

diff --git a/tests/admin_views/tests.py b/tests/admin_views/tests.py
index f7eaad659e..3377a6d441 100644
--- a/tests/admin_views/tests.py
+++ b/tests/admin_views/tests.py
@@ -11,7 +11,7 @@ from django.contrib import admin
 from django.contrib.admin import AdminSite, ModelAdmin
 from django.contrib.admin.helpers import ACTION_CHECKBOX_NAME
 from django.contrib.admin.models import ADDITION, DELETION, LogEntry
-from django.contrib.admin.options import TO_FIELD_VAR
+from django.contrib.admin.options import SOURCE_MODEL_VAR, TO_FIELD_VAR
 from django.contrib.admin.templatetags.admin_urls import add_preserved_filters
 from django.contrib.admin.tests import AdminSeleniumTestCase
 from django.contrib.admin.utils import quote
@@ -468,6 +468,126 @@ class AdminViewBasicTest(AdminViewBasicTestCase):
         response = self.client.post(reverse("admin:admin_views_article_add"), post_data)
         self.assertContains(response, "title with a new\\nline")
 
+    def test_popup_add_POST_with_valid_source_model(self):
+        """
+        Popup add with a valid source_model returns a successful response.
+        """
+        post_data = {
+            IS_POPUP_VAR: "1",
+            SOURCE_MODEL_VAR: "admin_views.section",
+            "title": "Test Article",
+            "content": "some content",
+            "date_0": "2010-09-10",
+            "date_1": "14:55:39",
+        }
+        response = self.client.post(reverse("admin:admin_views_article_add"), post_data)
+        self.assertEqual(response.status_code, 200)
+        self.assertContains(response, "data-popup-response")
+        messages = list(response.wsgi_request._messages)
+        self.assertEqual(len(messages), 0)
+
+    def test_popup_add_POST_with_optgroups(self):
+        """
+        Popup add with source_model containing optgroup choices includes
+        the optgroup in the response.
+        """
+        post_data = {
+            IS_POPUP_VAR: "1",
+            SOURCE_MODEL_VAR: "admin_views.section",
+            "title": "Test Article",
+            "content": "some content",
+            "date_0": "2010-09-10",
+            "date_1": "14:55:39",
+        }
+        response = self.client.post(
+            reverse("admin11:admin_views_article_add"), post_data
+        )
+        self.assertEqual(response.status_code, 200)
+        self.assertContains(response, ""optgroup": "Published"")
+
+    def test_popup_add_POST_without_optgroups(self):
+        """
+        Popup add where source_model form exists but doesn't have the field
+        should work without crashing.
+        """
+        post_data = {
+            IS_POPUP_VAR: "1",
+            SOURCE_MODEL_VAR: "admin_views.section",
+            "title": "Test Article 2",
+            "content": "some content",
+            "date_0": "2010-09-10",
+            "date_1": "14:55:39",
+        }
+        # Use regular admin (not admin11) where Section doesn't have optgroups.
+        response = self.client.post(reverse("admin:admin_views_article_add"), post_data)
+        self.assertEqual(response.status_code, 200)
+        self.assertContains(response, "data-popup-response")
+        self.assertNotContains(response, ""optgroup"")
+
+    def test_popup_add_POST_with_object_optgroups(self):
+        """
+        Popup add with source_model containing optgroups where the optgroup
+        keys are model instances (not strings) still serialize to strings.
+        """
+        post_data = {
+            IS_POPUP_VAR: "1",
+            SOURCE_MODEL_VAR: "admin_views.section",
+            "title": "Article 1",
+            "content": "some content",
+            "date_0": "2010-09-10",
+            "date_1": "14:55:39",
+        }
+        response = self.client.post(
+            reverse("admin12:admin_views_article_add"), post_data
+        )
+        self.assertEqual(response.status_code, 200)
+        # Check that optgroup is in the response with str() of Section instance
+        # The form uses Section.objects.all()[:2] which includes cls.s1
+        # ("Test section") as the first optgroup key (HTML encoded).
+        self.assertContains(response, ""optgroup": "Test section"")
+
+    def test_popup_add_POST_with_dynamic_optgroups(self):
+        """
+        Popup add with source_model where optgroup field is added dynamically
+        in __init__. This ensures the implementation doesn't rely on accessing
+        the uninstantiated form class's _meta or fields, but instead properly
+        instantiates the form with get_form(request)() to access field info.
+        """
+        post_data = {
+            IS_POPUP_VAR: "1",
+            SOURCE_MODEL_VAR: "admin_views.section",
+            "title": "Item 1",
+            "content": "some content",
+            "date_0": "2010-09-10",
+            "date_1": "14:55:39",
+        }
+        response = self.client.post(
+            reverse("admin13:admin_views_article_add"), post_data
+        )
+        self.assertEqual(response.status_code, 200)
+        self.assertContains(response, ""optgroup": "Category A"")
+
+    def test_popup_add_POST_with_invalid_source_model(self):
+        """
+        Popup add with an invalid source_model (non-existent app/model)
+        shows an error message instead of crashing.
+        """
+        post_data = {
+            IS_POPUP_VAR: "1",
+            SOURCE_MODEL_VAR: "admin_views.nonexistent",
+            "title": "Test Article",
+            "content": "some content",
+            "date_0": "2010-09-10",
+            "date_1": "14:55:39",
+        }
+        response = self.client.post(reverse("admin:admin_views_article_add"), post_data)
+        self.assertEqual(response.status_code, 200)
+        self.assertContains(response, "data-popup-response")
+        messages = list(response.wsgi_request._messages)
+        self.assertEqual(len(messages), 1)
+        self.assertIn("admin_views.nonexistent", str(messages[0]))
+        self.assertIn("could not be found", str(messages[0]))
+
     def test_basic_edit_POST(self):
         """
         A smoke test to ensure POST on edit_view works.