[deploy] Add top comments to articles feed (#6988)

* Add 'top_comments' to article feed

* Only include root comments

* Cache and eagerly load top comments

* Clear top comments cache when article score is updated

* Add articles.top_comments to bullet whitelist

* Update app/models/article.rb

Co-Authored-By: rhymes <rhymesete@gmail.com>

* Remove limit in top_comments association, remove Rails caching of top comments

* Remove unnecessary test

Co-authored-by: rhymes <rhymesete@gmail.com>

app/models/article.rb

@@ -29,6 +29,11 @@ class Article < ApplicationRecord
   counter_culture :organization
 
   has_many :comments, as: :commentable, inverse_of: :commentable
+  has_many :top_comments,
+           -> { where("comments.score > ? AND ancestry IS NULL", 10).order("comments.score DESC") },
+           as: :commentable,
+           inverse_of: :commentable,
+           class_name: "Comment"
   has_many :profile_pins, as: :pinnable, inverse_of: :pinnable
   has_many :buffer_updates, dependent: :destroy
   has_many :notifications, as: :notifiable, inverse_of: :notifiable, dependent: :delete_all
@@ -120,7 +125,8 @@ class Article < ApplicationRecord
            :video, :user_id, :organization_id, :video_source_url, :video_code,
            :video_thumbnail_url, :video_closed_caption_track_url, :language,
            :experience_level_rating, :experience_level_rating_distribution, :cached_user, :cached_organization,
-           :published_at, :crossposted_at, :boost_states, :description, :reading_time, :video_duration_in_seconds)
+           :published_at, :crossposted_at, :boost_states, :description, :reading_time, :video_duration_in_seconds,
+           :last_comment_at)
   }
 
   scope :limited_columns_internal_select, lambda {

app/services/articles/feed.rb

@@ -27,7 +27,7 @@ module Articles
     end
 
     def published_articles_by_tag
-      articles = Article.published.limited_column_select.page(@page).per(@number_of_articles)
+      articles = Article.published.limited_column_select.includes(:top_comments).page(@page).per(@number_of_articles)
       articles = articles.cached_tagged_with(@tag) if @tag.present? # More efficient than tagged_with
       articles
     end
@@ -213,7 +213,7 @@ module Articles
         hot_stories = hot_stories.offset(offset)
         new_stories = Article.published.
           where("score > ?", -15).
-          limited_column_select.order("published_at DESC").limit(rand(15..80))
+          limited_column_select.includes(:top_comments).order("published_at DESC").limit(rand(15..80))
         hot_stories = hot_stories.to_a + new_stories.to_a
       end
       [featured_story, hot_stories.to_a]

app/views/stories/feeds/show.json.jbuilder

@@ -24,5 +24,6 @@ json.array!(@stories) do |article|
   end
 
   json.tag_list article.cached_tag_list_array
+  json.top_comments article.top_comments
   json.extract! article, *article_methods_to_include
 end

config/environments/development.rb

@@ -1,3 +1,4 @@
+# rubocop:disable Metrics/BlockLength
 # Silence all Ruby 2.7 deprecation warnings
 $VERBOSE = nil
 
@@ -126,6 +127,7 @@ Rails.application.configure do
     Bullet.add_whitelist(type: :unused_eager_loading, class_name: "ApiSecret", association: :user)
     # acts-as-taggable-on has super weird eager loading problems: <https://github.com/mbleigh/acts-as-taggable-on/issues/91>
     Bullet.add_whitelist(type: :n_plus_one_query, class_name: "ActsAsTaggableOn::Tagging", association: :tag)
+    Bullet.add_whitelist(type: :unused_eager_loading, class_name: "Article", association: :top_comments)
 
     # Check if there are any data update scripts to run during startup
     if %w[c console runner s server].include?(ENV["COMMAND"])
@@ -137,3 +139,4 @@ Rails.application.configure do
 end
 
 Rails.application.routes.default_url_options = { host: Rails.application.config.app_domain }
+# rubocop:enable Metrics/BlockLength

config/environments/test.rb

@@ -68,6 +68,7 @@ Rails.application.configure do
     Bullet.add_whitelist(type: :unused_eager_loading, class_name: "ApiSecret", association: :user)
     # acts-as-taggable-on has super weird eager loading problems: <https://github.com/mbleigh/acts-as-taggable-on/issues/91>
     Bullet.add_whitelist(type: :n_plus_one_query, class_name: "ActsAsTaggableOn::Tagging", association: :tag)
+    Bullet.add_whitelist(type: :unused_eager_loading, class_name: "Article", association: :top_comments)
   end
 end
 

spec/models/article_spec.rb

@@ -845,6 +845,34 @@ RSpec.describe Article, type: :model do
     end
   end
 
+  describe "#top_comments" do
+    context "when article has comments" do
+      let(:root_comment) { create(:comment, commentable: article, score: 20) }
+      let(:child_comment) { create(:comment, commentable: article, score: 20, parent: root_comment) }
+
+      before do
+        root_comment
+        child_comment
+        create_list(:comment, 2, commentable: article, score: 20)
+        article.reload
+      end
+
+      it "returns comments with score greater than 10" do
+        expect(article.top_comments.first.score).to be > 10
+      end
+
+      it "only includes root comments" do
+        expect(article.top_comments).not_to include(child_comment)
+      end
+    end
+
+    context "when article does not have any comments" do
+      it "retrns empty set if there aren't any top comments" do
+        expect(article.top_comments).to be_empty
+      end
+    end
+  end
+
   describe "#touch_by_reaction" do
     it "reindexes elasticsearch doc" do
       sidekiq_assert_enqueued_with(job: Search::IndexToElasticsearchWorker, args: [described_class.to_s, article.search_id]) do

spec/requests/stories/feeds_spec.rb

@@ -114,6 +114,17 @@ RSpec.describe "Stories::Feeds", type: :request do
       end
     end
 
+    context "when there are highly rated comments" do
+      let(:comment) { create(:comment, score: 20) }
+      let(:article) { comment.commentable }
+
+      it "renders top comments for the article" do
+        get "/stories/feed/infinity", headers: headers
+
+        expect(response_article["top_comments"]).not_to be_nil
+      end
+    end
+
     context "when user is signed in but there's no field_test" do
       before do
         sign_in user