fix: check-in review round 3 — unused logger, JSON validation, query optimization

src/django_program/manage/views_checkin.py

@@ -62,7 +62,7 @@ def get_context_data(self, **kwargs: object) -> dict[str, object]:
         context["active_nav"] = "checkin"
 
         total_attendees = Attendee.objects.filter(conference=conference).count()
-        checked_in_count = Attendee.objects.filter(conference=conference, checkins__isnull=False).distinct().count()
+        checked_in_count = Attendee.objects.filter(conference=conference, checked_in_at__isnull=False).count()
         check_in_rate = round((checked_in_count / total_attendees * 100), 1) if total_attendees > 0 else 0
 
         today_start = timezone.now().replace(hour=0, minute=0, second=0, microsecond=0)

src/django_program/registration/views_checkin.py

@@ -7,7 +7,6 @@
 """
 
 import json
-import logging
 
 from django.db.models import Count, Prefetch
 from django.http import HttpRequest, HttpResponse, JsonResponse
@@ -20,8 +19,6 @@
 from django_program.registration.models import Order, OrderLineItem
 from django_program.registration.services.checkin import CheckInService, RedemptionService
 
-logger = logging.getLogger(__name__)
-
 
 class StaffRequiredMixin:
     """Require staff or superuser access for check-in API views.
@@ -100,11 +97,17 @@ def _get_ticket_type_name(order: Order | None) -> str:
 
 
 def _parse_json_body(request: HttpRequest) -> dict[str, object] | None:
-    """Parse JSON from request body, returning None on failure."""
+    """Parse JSON from request body, returning None on failure.
+
+    Returns None if the body is not valid JSON or is not an object (dict).
+    """
     try:
-        return json.loads(request.body)  # type: ignore[no-any-return]
+        payload = json.loads(request.body)
     except (json.JSONDecodeError, ValueError):
         return None
+    if not isinstance(payload, dict):
+        return None
+    return payload
 
 
 class ScanView(StaffRequiredMixin, View):