From c55f262b7fc72b1ca0660dd9e7371acb136a7ebf Mon Sep 17 00:00:00 2001
From: Sergio Marques <sergio@raylo.com>
Date: Thu, 9 Oct 2025 10:31:27 +0100
Subject: [PATCH] feat: add feature flag to control usage of query
 optimizations

---
 app/services/forest_liana/resources_getter.rb | 22 +++++----
 lib/forest_liana.rb                           |  2 +
 .../forest_liana/resources_getter_spec.rb     | 49 ++++++++++++++++++-
 3 files changed, 62 insertions(+), 11 deletions(-)

diff --git a/app/services/forest_liana/resources_getter.rb b/app/services/forest_liana/resources_getter.rb
index 9ded9c6c..eb98f631 100644
--- a/app/services/forest_liana/resources_getter.rb
+++ b/app/services/forest_liana/resources_getter.rb
@@ -30,17 +30,19 @@ def self.get_ids_from_request(params, user)
     end
 
     def perform
-      polymorphic_association, preload_loads = analyze_associations(@resource)
-      includes = @includes.uniq - polymorphic_association - preload_loads - @optional_includes
-      has_smart_fields = Array(@params.dig(:fields, @collection_name)&.split(',')).any? do |field|
-        ForestLiana::SchemaHelper.is_smart_field?(@resource, field)
-      end
+      @records = optimize_record_loading(@resource, @records, false)
 
-      if includes.empty? || has_smart_fields
-        @records = optimize_record_loading(@resource, @records, false)
-      else
-        select = compute_select_fields
-        @records = optimize_record_loading(@resource, @records, false).references(includes).select(*select)
+      if ForestLiana.optimize_query_select_fields
+        polymorphic_association, preload_loads = analyze_associations(@resource)
+        includes = @includes.uniq - polymorphic_association - preload_loads - @optional_includes
+        has_smart_fields = Array(@params.dig(:fields, @collection_name)&.split(',')).any? do |field|
+          ForestLiana::SchemaHelper.is_smart_field?(@resource, field)
+        end
+
+        if includes.any? && !has_smart_fields
+          select = compute_select_fields
+          @records = @records.references(includes).select(*select)
+        end
       end
 
       @records
diff --git a/lib/forest_liana.rb b/lib/forest_liana.rb
index 9d353b65..dc0715a7 100644
--- a/lib/forest_liana.rb
+++ b/lib/forest_liana.rb
@@ -29,6 +29,7 @@ module UserSpace
   mattr_accessor :meta
   mattr_accessor :logger
   mattr_accessor :reporter
+  mattr_accessor :optimize_query_select_fields
   # TODO: Remove once lianas prior to 2.0.0 are not supported anymore.
   mattr_accessor :names_old_overriden
 
@@ -42,6 +43,7 @@ module UserSpace
   self.meta = {}
   self.logger = nil
   self.reporter = nil
+  self.optimize_query_select_fields = true
 
   @config_dir = 'lib/forest_liana/**/*.rb'
 
diff --git a/spec/services/forest_liana/resources_getter_spec.rb b/spec/services/forest_liana/resources_getter_spec.rb
index 44928a32..9591a892 100644
--- a/spec/services/forest_liana/resources_getter_spec.rb
+++ b/spec/services/forest_liana/resources_getter_spec.rb
@@ -82,6 +82,7 @@ def clean_database
     describe 'records eager loading' do
       let(:resource) { Product }
       let(:fields) { { resource.name => 'id,name,manufacturer', 'manufacturer' => 'name' } }
+      let(:expected_selected_resource_attributes) { %w[id name manufacturer_id] }
 
       shared_context 'resource current_database' do
         before do
@@ -117,9 +118,31 @@ def connection.current_database
         end
       end
 
+      shared_examples 'filtered resource fields selection' do
+        it 'selects only the fields requested from the main resource' do
+          expected_non_selected_attributes = Product.attribute_names - expected_selected_resource_attributes
+
+          full_sql = getter.perform.to_sql
+
+          # Extract only the SELECT column list (between SELECT and the first FROM)
+          select_match = full_sql.match(/SELECT\s+(.*?)\s+FROM/i)
+          expect(select_match).not_to be_nil
+          select_columns_sql = select_match[1]
+
+          expected_selected_resource_attributes.each do |attribute|
+            expect(select_columns_sql).to include(%Q{"products"."#{attribute}"})
+          end
+
+          expected_non_selected_attributes.each do |attribute|
+            expect(select_columns_sql).not_to include(%Q{"products"."#{attribute}"})
+          end
+        end
+      end
+
       context 'when the connections do not support current_database' do
         include_examples 'left outer join'
         include_examples 'records'
+        include_examples 'filtered resource fields selection'
       end
 
       context 'when the included association uses a different database connection' do
@@ -151,6 +174,30 @@ def association_connection.current_database
 
         include_examples 'left outer join'
         include_examples 'records'
+        include_examples 'filtered resource fields selection'
+      end
+
+      context 'when the configuration to optimize query select fields is disabled' do
+        let(:expected_selected_resource_attributes) { Product.attribute_names }
+
+        before do
+          allow(ForestLiana).to receive(:optimize_query_select_fields).and_return(false)
+        end
+
+        include_examples 'records'
+
+        it 'selects all fields from the main resource' do
+          full_sql = getter.perform.to_sql
+
+           # Extract only the SELECT column list (between SELECT and the first FROM)
+          select_match = full_sql.match(/SELECT\s+(.*?)\s+FROM/i)
+          expect(select_match).not_to be_nil
+          select_columns_sql = select_match[1]
+
+          expected_selected_resource_attributes.each do |attribute|
+            expect(select_columns_sql).to include(%Q{"products"."#{attribute}"})
+          end
+        end
       end
     end
 
@@ -651,4 +698,4 @@ def association_connection.current_database
       end
     end
   end
-end
\ No newline at end of file
+end