refactor(src/dashboard): enhance DB query efficiency and pagination stability

Prevent N+1 queries, streamline aggregation, and fix role deletion count

src/dashboard/page_views/external_views.py

@@ -110,7 +110,8 @@ def external_access_view(request, token):
     if authenticated and access.is_active:
         tickets = (
             Ticket.objects.filter(project=access.project)
-            .select_related("status", "priority")
+            .select_related("status", "priority", "created_by", "epic")
+            .prefetch_related("assignees")
             .order_by("-created_at")
         )
         return render(

src/dashboard/page_views/notification_views.py

@@ -62,17 +62,17 @@ def notifications_list(request):
     except ValueError:
         per_page = 20
 
+    from django.db.models import Count
+
     paginator = Paginator(qs.select_related("user"), per_page)
     page_number = request.GET.get("page", 1)
     page_obj = paginator.get_page(page_number)
 
-    all_count = Notification.objects.filter(user=request.user).count()
-    unread_count = Notification.objects.filter(
-        user=request.user, read_at__isnull=True
-    ).count()
-    read_count = Notification.objects.filter(
-        user=request.user, read_at__isnull=False
-    ).count()
+    counts = Notification.objects.filter(user=request.user).aggregate(
+        all_count=Count("id"),
+        unread_count=Count("id", filter=Q(read_at__isnull=True)),
+        read_count=Count("id", filter=Q(read_at__isnull=False)),
+    )
 
     return render(
         request,
@@ -81,9 +81,9 @@ def notifications_list(request):
             "notifications": page_obj,
             "page_obj": page_obj,
             "filter": filter_param,
-            "all_count": all_count,
-            "unread_count": unread_count,
-            "read_count": read_count,
+            "all_count": counts["all_count"],
+            "unread_count": counts["unread_count"],
+            "read_count": counts["read_count"],
             "search_query": search_query,
             "type_filter": type_filter,
             "per_page": per_page,
@@ -93,7 +93,7 @@ def notifications_list(request):
 
 @require_http_methods(["GET"])
 def notifications_dropdown(request):
-    notifications = Notification.objects.filter(
+    notifications = Notification.objects.select_related("user").filter(
         user=request.user, read_at__isnull=True
     )[:10]
     return render(

src/dashboard/page_views/other_views.py

@@ -369,10 +369,11 @@ def role_delete(request, role_id):
     if role.is_system:
         messages.error(request, "System roles cannot be deleted.")
         return redirect("roles-list")
-    if role.users.exists():
+    user_count = role.users.count()
+    if user_count:
         messages.error(
             request,
-            f"Cannot delete role '{role.name}' — it is assigned to {role.users.count()} user(s).",
+            f"Cannot delete role '{role.name}' — it is assigned to {user_count} user(s).",
         )
         return redirect("roles-list")
     BoardRolePermission.objects.filter(role=role.slug).delete()

src/dashboard/page_views/project_views.py

@@ -187,7 +187,7 @@ def project_detail(request, project_id):
     # ─ Tickets with pagination ─
     tickets_qs = (
         Ticket.objects.filter(project=project)
-        .select_related("status", "priority")
+        .select_related("status", "priority", "created_by", "epic", "project")
         .prefetch_related("assignees")
         .order_by("-created_at")
     )
@@ -292,9 +292,9 @@ def project_detail(request, project_id):
             "today": today,
             "external_access": external_access,
             "is_admin": request.user.is_admin,
-            "permissions": BoardRolePermission.objects.filter(project=project).order_by(
-                "role"
-            ),
+            "permissions": BoardRolePermission.objects.filter(project=project)
+            .prefetch_related("move_to_statuses")
+            .order_by("role"),
             "role_choices": Role.objects.all(),
             "admin_roles": ADMIN_ROLES,
         },
@@ -396,7 +396,7 @@ def project_edit(request, project_id):
 
     tickets_qs = (
         Ticket.objects.filter(project=project)
-        .select_related("status", "priority")
+        .select_related("status", "priority", "created_by", "epic", "project")
         .prefetch_related("assignees")
         .order_by("-created_at")
     )

src/dashboard/page_views/ticket_views.py

@@ -4,6 +4,7 @@ from datetime import date
 import openpyxl
 from django.contrib import messages
 from django.contrib.auth import get_user_model
+from django.db import transaction
 from django.db.models import Count, Prefetch
 from django.http import HttpResponse, JsonResponse
 from django.shortcuts import get_object_or_404, redirect, render
@@ -774,39 +775,45 @@ def tickets_bulk_status(request):
             {"success": False, "error": "Missing ticket_ids or status_id"}, status=400
         )
 
-    status = get_object_or_404(TicketStatus, pk=status_id)
-    tickets = Ticket.objects.filter(pk__in=ticket_ids).select_related("status")
-
-    if not request.user.is_admin:
-        user_project_ids = request.user.projects.values_list("id", flat=True)
-        tickets = tickets.filter(project_id__in=user_project_ids)
-
-    count = 0
-    for ticket in tickets:
-        old_name = ticket.status.name
-        ticket.status = status
-        ticket.save(update_fields=["status", "updated_at"])
-
-        TicketHistory.objects.create(
-            ticket=ticket,
-            user=request.user,
-            status=status,
+    with transaction.atomic():
+        status = get_object_or_404(TicketStatus, pk=status_id)
+        tickets = (
+            Ticket.objects.select_for_update()
+            .filter(pk__in=ticket_ids)
+            .select_related("status", "created_by")
+            .prefetch_related("assignees")
         )
 
-        notify_users = list(ticket.assignees.all())
-        if ticket.created_by and ticket.created_by not in notify_users:
-            notify_users.append(ticket.created_by)
+        if not request.user.is_admin:
+            user_project_ids = request.user.projects.values_list("id", flat=True)
+            tickets = tickets.filter(project_id__in=user_project_ids)
 
-        for u in notify_users:
-            Notification.objects.create(
-                user=u,
-                type="status_changed",
-                title=f"Ticket {ticket.uuid} status changed",
-                message=f"Status changed from {old_name} to {status.name} by {request.user.get_full_name() or request.user.username}",
-                data={"ticket_id": ticket.id, "ticket_uuid": ticket.uuid},
+        count = 0
+        for ticket in tickets:
+            old_name = ticket.status.name
+            ticket.status = status
+            ticket.save(update_fields=["status", "updated_at"])
+
+            TicketHistory.objects.create(
+                ticket=ticket,
+                user=request.user,
+                status=status,
             )
 
-        count += 1
+            notify_users = list(ticket.assignees.all())
+            if ticket.created_by and ticket.created_by not in notify_users:
+                notify_users.append(ticket.created_by)
+
+            for u in notify_users:
+                Notification.objects.create(
+                    user=u,
+                    type="status_changed",
+                    title=f"Ticket {ticket.uuid} status changed",
+                    message=f"Status changed from {old_name} to {status.name} by {request.user.get_full_name() or request.user.username}",
+                    data={"ticket_id": ticket.id, "ticket_uuid": ticket.uuid},
+                )
+
+            count += 1
 
     return JsonResponse({"success": True, "count": count})
 

src/dashboard/page_views/user_views.py

@@ -46,6 +46,7 @@ def users_list(request):
         return redirect("dashboard")
     qs = (
         User.objects.filter(is_active=True)
+        .select_related("role")
         .annotate(
             project_count=Count("projects", distinct=True),
             ticket_count=Count("created_tickets", distinct=True),