optimze home page and product page

backend/product/serializers.py

@@ -122,12 +122,11 @@ class SubCategorySerializer(serializers.ModelSerializer):
                   'meta_description', 'product_count', 'parent', 'image']
 
     def get_product_count(self, obj):
-        # 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())
+        # Use annotated product_count from database annotation
+        return getattr(obj, 'product_count', 0)
 
     def get_parent(self, obj):
-        return obj.parent.name
+        return obj.parent.name if obj.parent else None
 
 
 class UnitCategorySerializer(serializers.ModelSerializer):
@@ -159,6 +158,7 @@ class DynamicProductSerializer(serializers.ModelSerializer):
     main_image = serializers.SerializerMethodField()
     customer_pickup_title = serializers.SerializerMethodField()
     customer_pickup_description = serializers.SerializerMethodField()
+    
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         view_type = self.context.get('view_type', 'all')
@@ -180,31 +180,48 @@ class DynamicProductSerializer(serializers.ModelSerializer):
             'chat': ['id', 'name', 'description', 'variants', 'image']
         }
 
+    def _get_best_deal_variant(self, obj):
+        """Get best deal variant from prefetched variants (pre-ordered by discount/price)"""
+        if not hasattr(self, '_best_deal_cache'):
+            self._best_deal_cache = {}
+        
+        if obj.id not in self._best_deal_cache:
+            # Get first from prefetched variants (already ordered by discount desc, price asc)
+            variants = list(obj.variants.all())
+            self._best_deal_cache[obj.id] = variants[0] if variants else None
+        
+        return self._best_deal_cache[obj.id]
+
     def get_main_image(self, obj):
         if obj.image:
             return obj.image.url
-        return obj.variants.first().images.first().image.url if obj.variants.exists() and obj.variants.first().images.exists() else None
+        # Use prefetched variants
+        variants = list(obj.variants.all())
+        if variants:
+            images = list(variants[0].images.all())
+            if images:
+                return images[0].image.url
+        return None
 
     def get_best_deal_price_before_discount(self, obj):
-        best_deal = obj.get_best_deal_variant()
+        best_deal = self._get_best_deal_variant(obj)
         if best_deal:
             return f'{best_deal.price:,.0f} تومانءءء'
         return 0
     
     def get_best_deal_price_after_discount(self, obj):
-        best_deal = obj.get_best_deal_variant()
+        best_deal = self._get_best_deal_variant(obj)
         if best_deal:
             price_after_discount = best_deal.price_after_discount
             return f'{price_after_discount:,.0f} تومانءءء'
         return 0
     
     def get_best_deal_discount(self, obj):
-        best_deal = obj.get_best_deal_variant()
+        best_deal = self._get_best_deal_variant(obj)
         if best_deal:
             return best_deal.discount
         return 0
 
-
     def get_customer_pickup_title(self, obj):
         if obj.shop:
             return obj.shop.customer_pickup_title
@@ -219,7 +236,7 @@ class DynamicProductSerializer(serializers.ModelSerializer):
         from account.models import UserFavorites
         request = self.context.get('request')
         if not request or not request.user.is_authenticated:
-            return False  # not logged in users haven't added anything
+            return False
 
         # Use exists() with filter instead of fetching all products
         return UserFavorites.objects.filter(user=request.user, products=obj).exists()
@@ -230,23 +247,24 @@ class DynamicProductSerializer(serializers.ModelSerializer):
             varients = obj.variants.filter(slider_category__isnull=False)
         else:
             varients = obj.variants.all()
-        colors = set(varient.color for varient in varients)
         return ProductVariantSerialzier(instance=varients, many=True, context=self.context).data
 
     def get_colors(self, obj):
-        # Use values_list to get only color field, reducing data transfer
-        colors = obj.variants.values_list('color', flat=True).distinct()
-        return list(filter(None, colors))  # Filter out None values
+        # Get colors from prefetched variants efficiently
+        variants = list(obj.variants.all())
+        colors = set()
+        for variant in variants:
+            if variant.color:
+                colors.add(variant.color)
+        return list(colors)
 
     def get_is_new(self, obj):
         return timezone.now() < obj.created_at + timedelta(days=7)
 
     def get_related_products(self, obj):
         if obj.related_products.all().count() >= 5:
-            # Limit to 10 related products
             related_products = obj.related_products.all()[:10]
         else:
-            # Limit category products and exclude current product
             related_products = obj.category.products.exclude(id=obj.id)[:10]
 
         serializer = DynamicProductSerializer(