Implement HTMX lazy-loading for exam collections and optimize queryset annotations for performance

generic/templates/generic/examcollection_detail.html

@@ -22,7 +22,7 @@
 
 
 
-        {% if object.anatomy_exams.all %}
+        {% if object.anatomy_count %}
             <div class="card mb-3">
                 <div class="card-header d-flex justify-content-between align-items-center">
                     <strong>Anatomy Exams</strong>
@@ -31,16 +31,14 @@
                         <button class="btn btn-sm btn-outline-primary" hx-get="{% url 'generic:exam_collection_add_marker' object.pk 'anatomy' %}" hx-target=".add-marker" hx-swap="innerHTML">Add marker</button>
                     </div>
                 </div>
-                <div class="card-body p-2">
+                <div class="card-body p-2" hx-get="{% url 'generic:exam_collection_exams_partial' object.pk 'anatomy' %}" hx-trigger="revealed" hx-swap="innerHTML">
-                    {% with exams=object.anatomy_exams.all app_name="anatomy" %}
+                    <div class="placeholder small text-muted">Loading anatomy exams…</div>
-                        {% include "exam_list.html#exam-list" %}
-                    {% endwith %}
                 </div>
                 <div class="card-footer add-marker small"></div>
             </div>
         {% endif %}
 
-        {% if object.longs_exams.all %}
+        {% if object.longs_count %}
             <div class="card mb-3">
                 <div class="card-header d-flex justify-content-between align-items-center">
                     <strong>Longs Exams</strong>
@@ -49,16 +47,14 @@
                         <button class="btn btn-sm btn-outline-primary" hx-get="{% url 'generic:exam_collection_add_marker' object.pk 'longs' %}" hx-target=".add-marker" hx-swap="innerHTML">Add marker</button>
                     </div>
                 </div>
-                <div class="card-body p-2">
+                <div class="card-body p-2" hx-get="{% url 'generic:exam_collection_exams_partial' object.pk 'longs' %}" hx-trigger="revealed" hx-swap="innerHTML">
-                    {% with exams=object.longs_exams.all app_name="longs" %}
+                    <div class="placeholder small text-muted">Loading longs exams…</div>
-                        {% include "exam_list.html#exam-list" %}
-                    {% endwith %}
                 </div>
                 <div class="card-footer add-marker small"></div>
             </div>
         {% endif %}
 
-        {% if object.rapids_exams.all %}
+        {% if object.rapids_count %}
             <div class="card mb-3">
                 <div class="card-header d-flex justify-content-between align-items-center">
                     <strong>Rapids Exams</strong>
@@ -67,16 +63,14 @@
                         <button class="btn btn-sm btn-outline-primary" hx-get="{% url 'generic:exam_collection_add_marker' object.pk 'rapids' %}" hx-target=".add-marker" hx-swap="innerHTML">Add marker</button>
                     </div>
                 </div>
-                <div class="card-body p-2">
+                <div class="card-body p-2" hx-get="{% url 'generic:exam_collection_exams_partial' object.pk 'rapids' %}" hx-trigger="revealed" hx-swap="innerHTML">
-                    {% with exams=object.rapids_exams.all app_name="rapids" %}
+                    <div class="placeholder small text-muted">Loading rapids exams…</div>
-                        {% include "exam_list.html#exam-list" %}
-                    {% endwith %}
                 </div>
                 <div class="card-footer add-marker small"></div>
             </div>
         {% endif %}
 
-        {% if object.shorts_exams.all %}
+        {% if object.shorts_count %}
             <div class="card mb-3">
                 <div class="card-header d-flex justify-content-between align-items-center">
                     <strong>Shorts Exams</strong>
@@ -85,39 +79,33 @@
                         <button class="btn btn-sm btn-outline-primary" hx-get="{% url 'generic:exam_collection_add_marker' object.pk 'shorts' %}" hx-target=".add-marker" hx-swap="innerHTML">Add marker</button>
                     </div>
                 </div>
-                <div class="card-body p-2">
+                <div class="card-body p-2" hx-get="{% url 'generic:exam_collection_exams_partial' object.pk 'shorts' %}" hx-trigger="revealed" hx-swap="innerHTML">
-                    {% with exams=object.shorts_exams.all app_name="shorts" %}
+                    <div class="placeholder small text-muted">Loading shorts exams…</div>
-                        {% include "exam_list.html#exam-list" %}
-                    {% endwith %}
                 </div>
                 <div class="card-footer add-marker small"></div>
             </div>
         {% endif %}
 
-        {% if object.physics_exams.all %}
+        {% if object.physics_count %}
             <div class="card mb-3">
                 <div class="card-header d-flex justify-content-between align-items-center">
                     <strong>Physics Exams</strong>
                     <a class="btn btn-sm btn-outline-secondary" href="{% url 'physics:exam_list_collection' object.pk %}">View exam list</a>
                 </div>
-                <div class="card-body p-2">
+                <div class="card-body p-2" hx-get="{% url 'generic:exam_collection_exams_partial' object.pk 'physics' %}" hx-trigger="revealed" hx-swap="innerHTML">
-                    {% with exams=object.physics_exams.all app_name="physics" %}
+                    <div class="placeholder small text-muted">Loading physics exams…</div>
-                        {% include "exam_list.html#exam-list" %}
-                    {% endwith %}
                 </div>
             </div>
         {% endif %}
 
-        {% if object.sbas_exams.all %}
+        {% if object.sbas_count %}
             <div class="card mb-3">
                 <div class="card-header d-flex justify-content-between align-items-center">
                     <strong>SBAs Exams</strong>
                     <a class="btn btn-sm btn-outline-secondary" href="{% url 'sbas:exam_list_collection' object.pk %}">View exam list</a>
                 </div>
-                <div class="card-body p-2">
+                <div class="card-body p-2" hx-get="{% url 'generic:exam_collection_exams_partial' object.pk 'sbas' %}" hx-trigger="revealed" hx-swap="innerHTML">
-                    {% with exams=object.sbas_exams.all app_name="sbas" %}
+                    <div class="placeholder small text-muted">Loading SBAs exams…</div>
-                        {% include "exam_list.html#exam-list" %}
-                    {% endwith %}
                 </div>
             </div>
         {% endif %}

generic/templates/generic/partials/exam_list_fragment.html

@@ -0,0 +1,6 @@
+{% load partials %}
+
+{% comment %} Minimal fragment rendering the exam-list partialdef for HTMX swaps. {% endcomment %}
+{% with exams=exams app_name=app_name marking=marking collection=collection %}
+    {% include "exam_list.html#exam-list" %}
+{% endwith %}

generic/urls.py

@@ -286,6 +286,7 @@ urlpatterns = [
     path("collection/<int:collection_id>/add_author", views.exam_collection_add_author, name="exam_collection_add_author"),
     path("collection/<int:collection_id>/bulk_add_groups", views.exam_collection_bulk_add_groups, name="exam_collection_bulk_add_groups"),
     path("collection/<int:collection_id>/add_marker/<str:exam_type>", views.exam_collection_add_marker, name="exam_collection_add_marker"),
+    path("collection/<int:collection_id>/exams/<str:exam_type>/partial", views.exam_collection_exams_partial, name="exam_collection_exams_partial"),
     path(
         "share_with_supervisor_toggle/<int:pk>/",
         views.toggle_share_with_supervisor,

generic/views.py

@@ -130,6 +130,89 @@ def cid_user_exam_partial(request, app_name: str, exam_id: int, cid: int):
     return render(request, "generic/partials/ciduserexam_detail_partial.html", {"cid_user_exam": cux})
 
 
+def exam_collection_exams_partial(request, collection_id: int, exam_type: str):
+    """Return the `exam-list` partial for a given collection and exam type.
+
+    This endpoint is intended for HTMX lazy-loading. It annotates candidate counts
+    and prefetches authors to avoid per-exam DB queries in the template.
+    """
+    collection = get_object_or_404(ExamCollection, pk=collection_id)
+
+    # Map exam_type to related name and model
+    EXAM_MAP = {
+        "anatomy": ("anatomy_exams", "anatomy"),
+        "longs": ("longs_exams", "longs"),
+        "rapids": ("rapids_exams", "rapids"),
+        "shorts": ("shorts_exams", "shorts"),
+        "physics": ("physics_exams", "physics"),
+        "sbas": ("sbas_exams", "sbas"),
+    }
+
+    if exam_type not in EXAM_MAP:
+        return HttpResponse("Unknown exam type", status=400)
+
+    rel_name, app_label = EXAM_MAP[exam_type]
+
+    # Attempt to import the model class for the app to annotate counts
+    ExamModel = None
+    try:
+        if exam_type == "anatomy":
+            from anatomy.models import Exam as AnatomyExam
+
+            ExamModel = AnatomyExam
+        elif exam_type == "longs":
+            from longs.models import Exam as LongsExam
+
+            ExamModel = LongsExam
+        elif exam_type == "rapids":
+            from rapids.models import Exam as RapidsExam
+
+            ExamModel = RapidsExam
+        elif exam_type == "shorts":
+            from shorts.models import Exam as ShortsExam
+
+            ExamModel = ShortsExam
+        elif exam_type == "physics":
+            from physics.models import Exam as PhysicsExam
+
+            ExamModel = PhysicsExam
+        elif exam_type == "sbas":
+            from sbas.models import Exam as SbasExam
+
+            ExamModel = SbasExam
+    except Exception:
+        ExamModel = None
+
+    # Build queryset on the related manager; filter archived false by default
+    related_qs = getattr(collection, rel_name).all().filter(archive=False)
+
+    if ExamModel is not None:
+        # Avoid evaluating the related manager multiple times; use ids
+        pks = list(related_qs.values_list("pk", flat=True))
+        related_qs = (
+            ExamModel.objects.filter(pk__in=pks)
+            .annotate(
+                valid_cid_users_count=Count("valid_cid_users"),
+                valid_user_users_count=Count("valid_user_users"),
+            )
+            .prefetch_related("author")
+            .order_by("name")
+        )
+
+    context = {
+        "exams": related_qs,
+        "app_name": app_label,
+        "marking": request.user.has_perm("generic.can_mark") if request.user.is_authenticated else False,
+        "collection": collection,
+    }
+
+    # Render only the fragment template which includes the `exam-list` partialdef
+    html = render_to_string(
+        "generic/partials/exam_list_fragment.html", context, request=request
+    )
+    return HttpResponse(html)
+
+
 from rapids.models import (
     Rapid as RapidQuestion,
     ExamQuestionDetail as RapidsExamQuestionDetail,
@@ -5875,68 +5958,34 @@ class ExamCollectionList(LoginRequiredMixin, ListView):
 
 class ExamCollectionDetail(AuthorRequiredMixin, DetailView):
     model = ExamCollection
-    
+    # Annotate counts for each exam type (non-archived) so template can check presence
+    # without evaluating entire related querysets.
     def get_queryset(self):
-        # Prefetch related exam sets and annotate candidate counts to avoid per-exam DB hits in templates
         qs = super().get_queryset()
+        counts = {
+            "anatomy_count": Count(
+                "anatomy_exams", filter=Q(anatomy_exams__archive=False), distinct=True
+            ),
+            "longs_count": Count(
+                "longs_exams", filter=Q(longs_exams__archive=False), distinct=True
+            ),
+            "physics_count": Count(
+                "physics_exams", filter=Q(physics_exams__archive=False), distinct=True
+            ),
+            "rapids_count": Count(
+                "rapids_exams", filter=Q(rapids_exams__archive=False), distinct=True
+            ),
+            "sbas_count": Count(
+                "sbas_exams", filter=Q(sbas_exams__archive=False), distinct=True
+            ),
+            "shorts_count": Count(
+                "shorts_exams", filter=Q(shorts_exams__archive=False), distinct=True
+            ),
+        }
         try:
-            from anatomy.models import Exam as AnatomyExam
+            return qs.annotate(**counts)
-            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
+            return qs
-            pass
-
-        return qs
 
 
 class ExamCollectionEdit(AuthorRequiredMixin, UpdateView):