Fix explore projects controller n+1 bullet report

app/controllers/explore/projects_controller.rb

@@ -80,7 +80,7 @@ class Explore::ProjectsController < Explore::ApplicationController
 
   # rubocop: disable CodeReuse/ActiveRecord
   def preload_associations(projects)
-    projects.includes(:route, :creator, :group, namespace: [:route, :owner])
+    projects.includes(:route, :creator, :group, :project_feature, namespace: [:route, :owner])
   end
   # rubocop: enable CodeReuse/ActiveRecord
 

changelogs/unreleased/tchu-fix-explore-projects-controller-n-1.yml

+---
+title: Fix N+1 issue in Explore Projects controller.
+merge_request: 36874
+author:
+type: performance

spec/controllers/explore/projects_controller_spec.rb

@@ -138,6 +138,33 @@ RSpec.describe Explore::ProjectsController do
     end
   end
 
+  shared_examples 'avoids N+1 queries' do
+    [:index, :trending, :starred].each do |endpoint|
+      describe "GET #{endpoint}" do
+        render_views
+
+        # some N+1 queries still exist
+        it 'avoids N+1 queries' do
+          projects = create_list(:project, 3, :repository, :public)
+          projects.each do |project|
+            pipeline = create(:ci_pipeline, :success, project: project, sha: project.commit.id)
+            create(:commit_status, :success, pipeline: pipeline, ref: pipeline.ref)
+          end
+
+          control = ActiveRecord::QueryRecorder.new { get endpoint }
+
+          new_projects = create_list(:project, 2, :repository, :public)
+          new_projects.each do |project|
+            pipeline = create(:ci_pipeline, :success, project: project, sha: project.commit.id)
+            create(:commit_status, :success, pipeline: pipeline, ref: pipeline.ref)
+          end
+
+          expect { get endpoint }.not_to exceed_query_limit(control).with_threshold(8)
+        end
+      end
+    end
+  end
+
   context 'when user is signed in' do
     let(:user) { create(:user) }
 
@@ -147,6 +174,7 @@ RSpec.describe Explore::ProjectsController do
 
     include_examples 'explore projects'
     include_examples "blocks high page numbers"
+    include_examples 'avoids N+1 queries'
 
     context 'user preference sorting' do
       let(:project) { create(:project) }
@@ -160,6 +188,7 @@ RSpec.describe Explore::ProjectsController do
   context 'when user is not signed in' do
     include_examples 'explore projects'
     include_examples "blocks high page numbers"
+    include_examples 'avoids N+1 queries'
 
     context 'user preference sorting' do
       let(:project) { create(:project) }