クエリ・パフォーマンスの改善（#258） (#259)

#258

#258

#258

Co-authored-by: miteruzo <miteruzo@naver.com>
Reviewed-on: #259

backend/app/controllers/posts_controller.rb

@@ -17,16 +17,17 @@ class PostsController < ApplicationController
         'posts.created_at)'
     q =
         filtered_posts
-        .preload(tags: :tag_name)
+        .preload(tags: { tag_name: :wiki_page })
         .with_attached_thumbnail
         .select("posts.*, #{ sort_sql } AS sort_ts")
         .order(Arel.sql("#{ sort_sql } DESC"))
-    posts = (
+    posts =
         if cursor
           q.where("#{ sort_sql } < ?", Time.iso8601(cursor)).limit(limit + 1)
         else
           q.limit(limit).offset(offset)
-        end).to_a
+        end
+        .to_a
 
     next_cursor = nil
     if cursor && posts.length > limit
@@ -52,7 +53,9 @@ class PostsController < ApplicationController
   end
 
   def random
-    post = filtered_posts.preload(tags: :tag_name).order('RAND()').first
+    post = filtered_posts.preload(tags: { tag_name: :wiki_page })
+                         .order('RAND()')
+                         .first
     return head :not_found unless post
 
     viewed = current_user&.viewed?(post) || false
@@ -64,7 +67,7 @@ class PostsController < ApplicationController
   end
 
   def show
-    post = Post.includes(tags: :tag_name).find(params[:id])
+    post = Post.includes(tags: { tag_name: :wiki_page }).find(params[:id])
     return head :not_found unless post
 
     viewed = current_user&.viewed?(post) || false
@@ -151,7 +154,7 @@ class PostsController < ApplicationController
   end
 
   def changes
-    id = params[:id]
+    id = params[:id].presence
     page = (params[:page].presence || 1).to_i
     limit = (params[:limit].presence || 20).to_i
 
@@ -162,30 +165,34 @@ class PostsController < ApplicationController
 
     pts = PostTag.with_discarded
     pts = pts.where(post_id: id) if id.present?
-    pts = pts.includes(:post, { tag: :tag_name }, :created_user, :deleted_user)
+    pts = pts.includes(:post, :created_user, :deleted_user,
+                       tag: { tag_name: :wiki_page })
 
     events = []
     pts.each do |pt|
+      tag = pt.tag.as_json(only: [:id, :category], methods: [:name, :has_wiki])
+      post = pt.post
+
       events << Event.new(
-          post:         pt.post,
-          tag:          pt.tag.as_json(only: [:id, :category], methods: [:name, :has_wiki]),
-          user:         pt.created_user && { id: pt.created_user.id, name: pt.created_user.name },
-          change_type:  'add',
-          timestamp:    pt.created_at)
+          post:,
+          tag:,
+          user: pt.created_user && { id: pt.created_user.id, name: pt.created_user.name },
+          change_type: 'add',
+          timestamp: pt.created_at)
 
       if pt.discarded_at
         events << Event.new(
-            post:         pt.post,
-            tag:          pt.tag.as_json(only: [:id, :category], methods: [:name, :has_wiki]),
-            user:         pt.deleted_user && { id: pt.deleted_user.id, name: pt.deleted_user.name },
-            change_type:  'remove',
-            timestamp:    pt.discarded_at)
+            post:,
+            tag:,
+            user: pt.deleted_user && { id: pt.deleted_user.id, name: pt.deleted_user.name },
+            change_type: 'remove',
+            timestamp: pt.discarded_at)
       end
     end
     events.sort_by!(&:timestamp)
     events.reverse!
 
-    render json: { changes: events.slice(offset, limit).as_json, count: events.size }
+    render json: { changes: (events.slice(offset, limit) || []).as_json, count: events.size }
   end
 
   private