feat: 広場のページネーション（#169） (#189)

#169 バグ修正

Merge remote-tracking branch 'origin/main' into feature/169

#169

Co-authored-by: miteruzo <miteruzo@naver.com>
Reviewed-on: https://git.miteruzo.com/miteruzo/btrc-hub/pulls/189

backend/app/controllers/posts_controller.rb

@@ -3,20 +3,35 @@ class PostsController < ApplicationController
 
   # GET /posts
   def index
-    limit = params[:limit].presence&.to_i
+    page = (params[:page].presence || 1).to_i
+    limit = (params[:limit].presence || 20).to_i
     cursor = params[:cursor].presence
 
-    created_at = ('COALESCE(posts.original_created_before - INTERVAL 1 SECOND,' +
-                  'posts.original_created_from,' +
-                  'posts.created_at)')
-    q = filtered_posts.order(Arel.sql("#{ created_at } DESC"))
-    q = q.where("#{ created_at } < ?", Time.iso8601(cursor)) if cursor
+    page = 1 if page < 1
+    limit = 1 if limit < 1
+
+    offset = (page - 1) * limit
 
-    posts = limit ? q.limit(limit + 1) : q
+    sort_sql =
+        'COALESCE(posts.original_created_before - INTERVAL 1 SECOND,' +
+        'posts.original_created_from,' +
+        'posts.created_at)'
+    q =
+        filtered_posts
+        .preload(:tags)
+        .with_attached_thumbnail
+        .select("posts.*, #{ sort_sql } AS sort_ts")
+        .order(Arel.sql("#{ sort_sql } DESC"))
+    posts = (
+        if cursor
+          q.where("#{ sort_sql } < ?", Time.iso8601(cursor)).limit(limit + 1)
+        else
+          q.limit(limit).offset(offset)
+        end).to_a
 
     next_cursor = nil
-    if limit && posts.size > limit
-      next_cursor = posts.last.created_at.iso8601(6)
+    if cursor && posts.length > limit
+      next_cursor = posts.last.read_attribute('sort_ts').iso8601(6)
       posts = posts.first(limit)
     end
 
@@ -29,7 +44,7 @@ class PostsController < ApplicationController
               nil
             end
       end
-    }, next_cursor: }
+    }, count: filtered_posts.count(:id), next_cursor: }
   end
 
   def random

frontend/src/pages/posts/PostListPage.tsx

@@ -7,6 +7,7 @@ import { Link, useLocation, useNavigationType } from 'react-router-dom'
 import PostList from '@/components/PostList'
 import TagSidebar from '@/components/TagSidebar'
 import WikiBody from '@/components/WikiBody'
+import Pagination from '@/components/common/Pagination'
 import TabGroup, { Tab } from '@/components/common/TabGroup'
 import MainArea from '@/components/layout/MainArea'
 import { API_BASE_URL, SITE_TITLE } from '@/config'
@@ -23,6 +24,7 @@ export default () => {
   const [cursor, setCursor] = useState ('')
   const [loading, setLoading] = useState (false)
   const [posts, setPosts] = useState<Post[]> ([])
+  const [totalPages, setTotalPages] = useState (0)
   const [wikiPage, setWikiPage] = useState<WikiPage | null> (null)
 
   const loadMore = async (withCursor: boolean) => {
@@ -31,15 +33,19 @@ export default () => {
     const res = await axios.get (`${ API_BASE_URL }/posts`, {
 	params: { tags:   tags.join (' '),
 		  match:  anyFlg ? 'any' : 'all',
-		  limit:  '20',
+		  ...(page && { page }),
+		  ...(limit && { limit }),
 		  ...(withCursor && { cursor }) } })
-    const data = toCamel (res.data as any, { deep: true }) as { posts:      Post[]
-								nextCursor: string }
+    const data = toCamel (res.data as any, { deep: true }) as {
+	posts:      Post[]
+	count:      number
+	nextCursor: string }
     setPosts (posts => (
 	[...((new Map ([...(withCursor ? posts : []), ...data.posts]
 		       .map (post => [post.id, post])))
 	     .values ())]))
     setCursor (data.nextCursor)
+    setTotalPages (Math.ceil (data.count / limit))
 
     setLoading (false)
   }
@@ -49,6 +55,8 @@ export default () => {
   const tagsQuery = query.get ('tags') ?? ''
   const anyFlg = query.get ('match') === 'any'
   const tags = tagsQuery.split (' ').filter (e => e !== '')
+  const page = Number (query.get ('page') ?? 1)
+  const limit = Number (query.get ('limit') ?? 20)
 
   useEffect(() => {
     const observer = new IntersectionObserver (entries => {
@@ -65,7 +73,8 @@ export default () => {
   }, [loaderRef, loading])
 
   useLayoutEffect (() => {
-    const savedState = sessionStorage.getItem (`posts:${ tagsQuery }`)
+    // TODO: 無限ロード用
+    const savedState = /* sessionStorage.getItem (`posts:${ tagsQuery }`) */ null
     if (savedState && navigationType === 'POP')
       {
 	const { posts, cursor, scroll } = JSON.parse (savedState)
@@ -116,18 +125,23 @@ export default () => {
 	<MainArea>
 	  <TabGroup>
 	    <Tab name="広場">
-	      {posts.length
+	      {posts.length > 0
 	       ? (
-		  <PostList posts={posts} onClick={() => {
-		    const statesToSave = {
-			posts, cursor,
-			scroll: containerRef.current?.scrollTop ?? 0 }
-		    sessionStorage.setItem (`posts:${ tagsQuery }`,
-					    JSON.stringify (statesToSave))
-		  }}/>)
+		  <>
+		    <PostList posts={posts} onClick={() => {
+		      // TODO: 無限ロード用なので復活時に戻す．
+		      // const statesToSave = {
+		      //     posts, cursor,
+		      //     scroll: containerRef.current?.scrollTop ?? 0 }
+		      // sessionStorage.setItem (`posts:${ tagsQuery }`,
+		      //                         JSON.stringify (statesToSave))
+		    }}/>
+		    <Pagination page={page} totalPages={totalPages}/>
+		  </>)
 	       : !(loading) && '広場には何もありませんよ．'}
 	      {loading && 'Loading...'}
-	      <div ref={loaderRef} className="h-12"/>
+	      {/* TODO: 無限ローディング復活までコメント・アウト */}
+	      {/* <div ref={loaderRef} className="h-12"/> */}
 	    </Tab>
 	    {tags.length === 1 && (
 		<Tab name="Wiki">