From b424defd57d167a76ca6420a243ba2dac66a02cc Mon Sep 17 00:00:00 2001
From: Ross <ross@xkjq.uk>
Date: Fri, 7 Nov 2025 22:16:24 +0000
Subject: [PATCH] Optimize exam collection queries by annotating exam counts
 and prefetching authors to improve template performance

---
 .../generic/examcollection_list.html          | 10 +++----
 generic/views.py                              | 26 ++++++++++++++++++-
 2 files changed, 29 insertions(+), 7 deletions(-)

diff --git a/generic/templates/generic/examcollection_list.html b/generic/templates/generic/examcollection_list.html
index 5f2f1743..91660075 100755
--- a/generic/templates/generic/examcollection_list.html
+++ b/generic/templates/generic/examcollection_list.html
@@ -27,12 +27,10 @@
                         <span class="badge bg-secondary" title="Archived">Archived</span>
                     {% endif %}
 
-                    {# Total exams count (sum of known related exam sets) #}
-                        {% with a=collection.anatomy_exams.count l=collection.longs_exams.count p=collection.physics_exams.count r=collection.rapids_exams.count s=collection.sbas_exams.count %}
-                        {% with total=a|add:l|add:p|add:r|add:s %}
-                            <span class="badge bg-info text-dark ms-1" title="Total exams">{{ total }} exams</span>
-                        {% endwith %}
-                        {# Per-type badges (only show non-zero) #}
+                    {# Use annotated counts provided by the view to avoid per-card COUNT queries #}
+                    <span class="badge bg-info text-dark ms-1" title="Total exams">{{ collection.total_count }} exams</span>
+                    {# Per-type badges (only show non-zero) #}
+                    {% with a=collection.anatomy_count l=collection.longs_count p=collection.physics_count r=collection.rapids_count s=collection.sbas_count %}
                         {% if a %}<span class="badge bg-primary ms-1">Anatomy {{ a }}</span>{% endif %}
                         {% if l %}<span class="badge bg-primary ms-1">Longs {{ l }}</span>{% endif %}
                         {% if p %}<span class="badge bg-primary ms-1">Physics {{ p }}</span>{% endif %}
diff --git a/generic/views.py b/generic/views.py
index ca86f9b9..2bba6213 100644
--- a/generic/views.py
+++ b/generic/views.py
@@ -67,7 +67,7 @@ from generic.mixins import CheckCanEditMixin, SuperuserRequiredMixin
 
 import zipfile
 from django.core.files.base import ContentFile
-from django.db.models import Q
+from django.db.models import Q, Count, F
 
 from .forms import (
     CidGroupExamForm,
@@ -4777,6 +4777,30 @@ class SupervisorList(CidManagerRequiredMixin, SingleTableMixin, FilterView):
 
 class ExamCollectionList(ListView):
     model = ExamCollection
+    
+    def get_queryset(self):
+        """Annotate exam counts per collection and prefetch authors to avoid N+1 queries in templates."""
+        qs = (
+            ExamCollection.objects.all()
+            .annotate(
+                anatomy_count=Count("anatomy_exams", filter=Q(anatomy_exams__archive=False)),
+                longs_count=Count("longs_exams", filter=Q(longs_exams__archive=False)),
+                physics_count=Count("physics_exams", filter=Q(physics_exams__archive=False)),
+                rapids_count=Count("rapids_exams", filter=Q(rapids_exams__archive=False)),
+                sbas_count=Count("sbas_exams", filter=Q(sbas_exams__archive=False)),
+            )
+            .annotate(
+                total_count=F("anatomy_count")
+                +F("longs_count")
+                +F("physics_count")
+                +F("rapids_count")
+                +F("sbas_count")
+            )
+            .prefetch_related("author")
+            .order_by("name")
+        )
+
+        return qs
 
 
 class ExamCollectionDetail(DetailView, AuthorRequiredMixin):