From b1962e1e6d33357fe6813283c9be5b429ef5a829 Mon Sep 17 00:00:00 2001
From: Chris Doehring <chrisdoehring@gmail.com>
Date: Mon, 1 Jun 2026 16:37:06 -0700
Subject: [PATCH] fix: autocomplete inline FKs to stop Route admin change page
 timing out

The Django admin Route change page renders RouteProviderInline and
RouteDestinationInline, each of which renders a <select> of *every*
Integration for every inline row and every extra form. Integration.__str__
touches owner.name and type.name (neither select_related), so building those
dropdowns is an N+1 storm whose cost scales with the integration count -- the
cause of the change page timing out in production.

Adding autocomplete_fields = ("integration",) to both inlines replaces the
full-table dropdowns with AJAX autocomplete (backed by IntegrationAdmin's
existing search_fields), so no Integration options are pre-rendered.

A regression test renders the change page, adds 100 integrations, and asserts
the query count stays flat. Before the fix it went 460 -> 4259 queries; after,
it stays within a small constant.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 cdip_admin/integrations/admin.py            |  5 ++
 cdip_admin/integrations/tests/test_admin.py | 53 +++++++++++++++++++++
 2 files changed, 58 insertions(+)
 create mode 100644 cdip_admin/integrations/tests/test_admin.py

diff --git a/cdip_admin/integrations/admin.py b/cdip_admin/integrations/admin.py
index 2b8e57e08..d1362186d 100644
--- a/cdip_admin/integrations/admin.py
+++ b/cdip_admin/integrations/admin.py
@@ -436,10 +436,15 @@ class WebhookConfigurationAdmin(admin.ModelAdmin):
 
 class RouteProviderInline(admin.TabularInline):
     model = Route.data_providers.through
+    # Without this, every inline row renders a <select> of *every* Integration,
+    # and Integration.__str__ touches owner.name/type.name (not select_related),
+    # making the Route change page an N+1 storm that times out in production.
+    autocomplete_fields = ("integration",)
 
 
 class RouteDestinationInline(admin.TabularInline):
     model = Route.destinations.through
+    autocomplete_fields = ("integration",)
 
 
 @admin.register(Route)
diff --git a/cdip_admin/integrations/tests/test_admin.py b/cdip_admin/integrations/tests/test_admin.py
new file mode 100644
index 000000000..5964efd2d
--- /dev/null
+++ b/cdip_admin/integrations/tests/test_admin.py
@@ -0,0 +1,53 @@
+import pytest
+from django.db import connection
+from django.test.utils import CaptureQueriesContext
+from django.urls import reverse
+
+from integrations.models import Integration
+
+pytestmark = pytest.mark.django_db
+
+
+def _render_query_count(admin_client, url):
+    with CaptureQueriesContext(connection) as ctx:
+        response = admin_client.get(url)
+    assert response.status_code == 200, response.status_code
+    return len(ctx.captured_queries)
+
+
+def test_route_change_page_does_not_scale_with_integration_count(
+    admin_client, route_1, organization, integration_type_er
+):
+    """The Route change page renders RouteProvider/RouteDestination inlines.
+
+    Without autocomplete_fields, each inline renders a <select> of *every*
+    Integration, and Integration.__str__ touches owner.name and type.name
+    (neither select_related), so building the dropdowns is an N+1 storm whose
+    cost grows with the number of integrations -- the cause of the timeout.
+    The query count must stay flat as integrations are added.
+    """
+    url = reverse("admin:integrations_route_change", args=[route_1.pk])
+
+    baseline = _render_query_count(admin_client, url)
+
+    # bulk_create bypasses save hooks/dispatcher deployment -- we only need
+    # rows that would populate the inline FK dropdowns.
+    Integration.objects.bulk_create(
+        [
+            Integration(
+                type=integration_type_er,
+                owner=organization,
+                name=f"Bulk Integration {i}",
+                base_url=f"https://bulk-{i}.example.org",
+            )
+            for i in range(100)
+        ]
+    )
+
+    after = _render_query_count(admin_client, url)
+
+    assert after - baseline <= 10, (
+        "Route change page query count scales with integration count: "
+        f"{baseline} queries -> {after} queries after adding 100 integrations. "
+        "Inline FK fields should use autocomplete_fields."
+    )