From bf0817ed342333bcfff1f7e2f951b427aabb2dcd Mon Sep 17 00:00:00 2001
From: Parsa Nazer <parsa.nazerrr@gmail.com>
Date: Mon, 3 Nov 2025 11:56:47 +0330
Subject: [PATCH] Optimize product count retrieval and enhance query
 performance with prefetch_related

---
 backend/product/serializers.py |  4 +++-
 backend/product/views.py       | 14 ++++++++++++--
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/backend/product/serializers.py b/backend/product/serializers.py
index ef23c8a..ec6d695 100644
--- a/backend/product/serializers.py
+++ b/backend/product/serializers.py
@@ -102,7 +102,9 @@ class SubCategorySerializer(serializers.ModelSerializer):
                   'meta_description', 'product_count', 'parent', 'image']
 
     def get_product_count(self, obj):
-        return obj.products.count()
+        # Use annotated product_count if available (from optimized query)
+        # Otherwise fall back to counting (for backward compatibility)
+        return getattr(obj, 'product_count', obj.products.count())
 
     def get_parent(self, obj):
         return obj.parent.name
diff --git a/backend/product/views.py b/backend/product/views.py
index c772ee7..b2a991b 100644
--- a/backend/product/views.py
+++ b/backend/product/views.py
@@ -14,7 +14,7 @@ from drf_spectacular.utils import extend_schema, OpenApiParameter, OpenApiTypes
 from rest_framework.permissions import AllowAny
 from order.serializers import OrderItemSerailzier
 from order.models import OrderModel
-from django.db.models import Min, Max
+from django.db.models import Min, Max, Count, Prefetch
 from home.models import ShowCaseSlider
 from home.serializers import ShowCaseSliderSerialzier
 from order.models import Cart, CartItem
@@ -51,7 +51,17 @@ class AllCategories(APIView):
         # if search_query:
         #     categories = MainCategoryModel.objects.filter(Q(name__icontains=search_query) | Q(slug__icontains=search_query))
         # else:
-        categories = MainCategoryModel.objects.all()
+
+        # Optimize query with prefetch_related to avoid N+1 queries
+        categories = MainCategoryModel.objects.prefetch_related(
+            Prefetch(
+                'subcategorys',
+                queryset=SubCategoryModel.objects.annotate(
+                    product_count=Count('products')
+                )
+            )
+        ).all()
+
         categories_ser = self.serializer_class(
             instance=categories, many=True, context={'request': request})
         return Response(categories_ser.data, status=status.HTTP_200_OK)