Enhance ExamCollectionDetail queryset to prefetch related exams and annotate candidate counts for improved performance in templates

generic/views.py

@@ -5876,6 +5876,68 @@ class ExamCollectionList(LoginRequiredMixin, ListView):
 class ExamCollectionDetail(AuthorRequiredMixin, DetailView):
     model = ExamCollection
     
+    def get_queryset(self):
+        # Prefetch related exam sets and annotate candidate counts to avoid per-exam DB hits in templates
+        qs = super().get_queryset()
+        try:
+            from anatomy.models import Exam as AnatomyExam
+            from longs.models import Exam as LongsExam
+            from rapids.models import Exam as RapidsExam
+            from shorts.models import Exam as ShortsExam
+            from physics.models import Exam as PhysicsExam
+            from sbas.models import Exam as SbasExam
+
+            qs = qs.prefetch_related(
+                Prefetch(
+                    'anatomy_exams',
+                    queryset=AnatomyExam.objects.annotate(
+                        valid_cid_users_count=Count('valid_cid_users'),
+                        valid_user_users_count=Count('valid_user_users'),
+                    ).prefetch_related('author'),
+                ),
+                Prefetch(
+                    'longs_exams',
+                    queryset=LongsExam.objects.annotate(
+                        valid_cid_users_count=Count('valid_cid_users'),
+                        valid_user_users_count=Count('valid_user_users'),
+                    ).prefetch_related('author'),
+                ),
+                Prefetch(
+                    'rapids_exams',
+                    queryset=RapidsExam.objects.annotate(
+                        valid_cid_users_count=Count('valid_cid_users'),
+                        valid_user_users_count=Count('valid_user_users'),
+                    ).prefetch_related('author'),
+                ),
+                Prefetch(
+                    'shorts_exams',
+                    queryset=ShortsExam.objects.annotate(
+                        valid_cid_users_count=Count('valid_cid_users'),
+                        valid_user_users_count=Count('valid_user_users'),
+                    ).prefetch_related('author'),
+                ),
+                Prefetch(
+                    'physics_exams',
+                    queryset=PhysicsExam.objects.annotate(
+                        valid_cid_users_count=Count('valid_cid_users'),
+                        valid_user_users_count=Count('valid_user_users'),
+                    ).prefetch_related('author'),
+                ),
+                Prefetch(
+                    'sbas_exams',
+                    queryset=SbasExam.objects.annotate(
+                        valid_cid_users_count=Count('valid_cid_users'),
+                        valid_user_users_count=Count('valid_user_users'),
+                    ).prefetch_related('author'),
+                ),
+                'author',
+            )
+        except Exception:
+            # If any app is missing or import fails, fall back to default queryset
+            pass
+
+        return qs
+
 
 class ExamCollectionEdit(AuthorRequiredMixin, UpdateView):
     model = ExamCollection

templates/exam_list.html

@@ -17,9 +17,24 @@
                     {% if app_name == 'anatomy' %}<a href="{% url 'anatomy:mark2_overview' pk=exam.pk %}" class="flex-col-half">Mark2</a>{% endif %}
                 {% endif %}
                 <span class="flex-col">
-                    <a href="{% url app_name|add:':exam_cids' exam_id=exam.pk %}">Candidates</a> <span class="candidate-counts">[<span title="Number of active CID users">
+                    <a href="{% url app_name|add:':exam_cids' exam_id=exam.pk %}">Candidates</a>
-                        {{exam.valid_cid_users.count}}
+                    <span class="candidate-counts">[
-                    </span> / <span title="Number of active User users">{{exam.valid_user_users.count}}]</span></span>
+                        <span title="Number of active CID users">
+                            {% if exam.valid_cid_users_count is not None %}
+                                {{ exam.valid_cid_users_count }}
+                            {% else %}
+                                {{ exam.valid_cid_users.count }}
+                            {% endif %}
+                        </span>
+                        /
+                        <span title="Number of active User users">
+                            {% if exam.valid_user_users_count is not None %}
+                                {{ exam.valid_user_users_count }}
+                            {% else %}
+                                {{ exam.valid_user_users.count }}
+                            {% endif %}
+                        ]</span>
+                    </span>
                 </span>
                 <a href="{% url app_name|add:':exam_scores_all' pk=exam.pk %}" class="flex-col-half">Scores</a>
                 <input type="checkbox" id="active-{{exam.pk}}" class="exam-active-switch" data-posturl="{% url app_name|add:':exam_toggle_active' pk=exam.pk %}" {% if exam.active %}checked{% endif %}>