#206

backend/app/controllers/posts_controller.rb

@@ -30,8 +30,20 @@ class PostsController < ApplicationController
 
     offset = (page - 1) * limit
 
+    pt_max_sql =
+        PostTag
+        .select('post_id, MAX(updated_at) AS max_updated_at')
+        .group('post_id')
+        .to_sql
+
+    updated_at_all_sql =
+        'GREATEST(posts.updated_at,' +
+        'COALESCE(pt_max.max_updated_at, posts.updated_at))'
+
     q =
         filtered_posts
+        .joins("LEFT JOIN (#{ pt_max_sql }) pt_max ON pt_max.post_id = posts.id")
+        .reselect('posts.*', Arel.sql("#{ updated_at_all_sql } AS updated_at_all"))
         .preload(tags: { tag_name: :wiki_page })
         .with_attached_thumbnail
 
@@ -45,8 +57,12 @@ class PostsController < ApplicationController
     end
     q = q.where('posts.created_at >= ?', created_between[0]) if created_between[0]
     q = q.where('posts.created_at <= ?', created_between[1]) if created_between[1]
-    q = q.where('posts.updated_at >= ?', updated_between[0]) if updated_between[0]
-    q = q.where('posts.updated_at <= ?', updated_between[1]) if updated_between[1]
+    if updated_between[0]
+      q = q.where("#{ updated_at_all_sql } >= ?", updated_between[0])
+    end
+    if updated_between[1]
+      q = q.where("#{ updated_at_all_sql } <= ?", updated_between[1])
+    end
 
     sort_sql =
         if order[0] == 'original_created_at'
@@ -57,12 +73,12 @@ class PostsController < ApplicationController
         else
           "posts.#{ order[0] } #{ order[1] }"
         end
-    posts = q.select('posts.*')
-             .order(Arel.sql("#{ sort_sql }"))
-             .limit(limit).offset(offset).to_a
+    posts = q.order(Arel.sql("#{ sort_sql }")).limit(limit).offset(offset).to_a
+
+    q = q.except(:select, :order)
 
     render json: { posts: posts.map { |post|
-      PostRepr.base(post).tap do |json|
+      PostRepr.base(post).merge(updated_at: post.updated_at_all).tap do |json|
         json['thumbnail'] =
             if post.thumbnail.attached?
               rails_storage_proxy_url(post.thumbnail, only_path: false)