Try to reduce DB trips when displaying the user's order history

backend/api/orders_serializers.py

@@ -92,6 +92,25 @@ class Meta:
         )
         model = Order
 
+    # TODO: commented code doesn't reduce DB hits
+    @classmethod
+    def setup_eager_loading(cls, queryset):
+        """Perform necessary eager loading of orders data."""
+        return queryset.select_related("user")
+        # ).prefetch_related(
+        #     Prefetch(
+        #         "products",
+        #         queryset=Product.objects.select_related(
+        #             "category", "subcategory", "producer"
+        #         ).prefetch_related(
+        #             "components",
+        #             "tags",
+        #             "promotions",
+        #             "reviews",
+        #         ),
+        #     )
+        # )
+
 
 class OrderGetAnonSerializer(serializers.ModelSerializer):
     """Serializer for anonimous user order representation."""

backend/api/orders_views.py

@@ -2,7 +2,6 @@
 from django.conf import settings
 from django.contrib.sites.shortcuts import get_current_site
 from django.core.exceptions import PermissionDenied
-from django.db.models import Prefetch
 from django.utils.decorators import method_decorator
 from drf_standardized_errors.openapi_serializers import (
     ErrorResponse401Serializer,
@@ -209,7 +208,7 @@ class OrderViewSet(
 ):
     """Viewset for Order."""
 
-    queryset = Order.objects.all()
+    queryset = OrderGetAuthSerializer.setup_eager_loading(Order.objects.all())
     permission_classes = [AllowAny]
 
     def get_serializer_class(self):
@@ -267,17 +266,8 @@ def retrieve(self, request, **kwargs):
 
     def list(self, request, **kwargs):
         if self.request.user.is_authenticated:
-            queryset = (
-                Order.objects.select_related("user", "address", "delivery_point")
-                .prefetch_related(
-                    Prefetch(
-                        "products",
-                        queryset=Product.objects.prefetch_related("promotions"),
-                    )
-                )
-                .filter(user=self.request.user)
-            )
-            serializer = self.get_serializer(queryset, many=True)
+            queryset = self.get_queryset().filter(user=self.request.user)
+            serializer = self.get_serializer(queryset, many=True)  # similar DB hits
             return Response(serializer.data, status=status.HTTP_200_OK)
         return Response(
             {"errors": METHOD_ERROR_MESSAGE},

backend/api/products_serializers.py

@@ -195,7 +195,7 @@ class Meta:
 
     @classmethod
     def setup_eager_loading(cls, queryset, user):
-        """Perform necessary eager loading of product data."""
+        """Perform necessary eager loading of products data."""
         if user.is_anonymous:
             queryset = (
                 queryset.select_related("category", "subcategory", "producer")

backend/api/products_views.py

@@ -522,13 +522,8 @@ def get_serializer_class(self):
         return ProductSerializer
 
     def get_queryset(self):
-        return (
-            ProductSerializer.setup_eager_loading(
-                Product.objects.all(), self.request.user
-            )
-            # Product.objects.select_related("category", "subcategory", "producer")
-            # .prefetch_related("components", "tags", "promotions", "reviews")
-            # .annotate(rating=Avg("reviews__score"))
+        return ProductSerializer.setup_eager_loading(
+            Product.objects.all(), self.request.user
         )
 
     @transaction.atomic

backend/api/recipes_serializers.py

@@ -88,6 +88,7 @@ def get_need_to_buy(self, obj) -> int:
         return ceil(obj.amount / obj.ingredient.amount)
 
 
+# TODO: make setup_eager_loading cls method
 class RecipeSerializer(serializers.ModelSerializer):
     """Serializer for recipe representation."""