[๐Ÿค–] React์˜ `useOptimistic` ํ›…์œผ๋กœ ๋‚™๊ด€์  UI ์—…๋ฐ์ดํŠธ ๊ตฌํ˜„ํ•˜๊ธฐ: Server Actions์™€ ํ•จ๊ป˜

React 18/19์˜ `useOptimistic` ํ›…์„ ํ™œ์šฉํ•˜์—ฌ Server Actions์™€ ์—ฐ๋™๋˜๋Š” ๋‚™๊ด€์  UI ์—…๋ฐ์ดํŠธ๋ฅผ ๊ตฌํ˜„ํ•˜๋Š” ๋ฐฉ๋ฒ•์„ ์‹ค์šฉ์ ์ธ ์˜ˆ์‹œ์™€ ํ•จ๊ป˜ ์ž์„ธํžˆ ์•Œ์•„๋ด์š”. ์‚ฌ์šฉ์ž ๊ฒฝํ—˜์„ ๊ฐœ์„ ํ•˜๊ณ  ์• ํ”Œ๋ฆฌ์ผ€์ด์…˜์˜ ๋ฐ˜์‘์„ฑ์„ ๋†’์ด๋Š” ๋…ธํ•˜์šฐ๋ฅผ ๊ณต์œ ํ•ด์š”.

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๐Ÿค– ์ด ํฌ์ŠคํŒ…์€ Gemini 2.5 Flash AI๊ฐ€ ์ž‘์„ฑํ–ˆ์–ด์š”.
๋‚ด์šฉ์˜ ์ •ํ™•์„ฑ์„ ์œ„ํ•ด ๊ฒ€ํ† ๋ฅผ ๊ฑฐ์ณค์ง€๋งŒ, ์‹ค๋ฌด ์ ์šฉ ์ „ ๊ณต์‹ ๋ฌธ์„œ๋ฅผ ํ•จ๊ป˜ ์ฐธ๊ณ ํ•ด ์ฃผ์„ธ์š”.

์œ ์šฉํ•œ ํŒ

React์˜ useOptimistic ํ›…์„ ์‚ฌ์šฉํ•˜์—ฌ Server Actions์™€ ์—ฐ๋™๋˜๋Š” ๋‚™๊ด€์  UI๋ฅผ ์–ด๋–ป๊ฒŒ ๊ตฌํ˜„ํ•˜๊ณ , ์ด๋ฅผ ํ†ตํ•ด ์‚ฌ์šฉ์ž ๊ฒฝํ—˜์„ ๊ฐœ์„ ํ•˜๋Š”์ง€ ์‹ฌ์ธต์ ์œผ๋กœ ์‚ดํŽด๋ณด์•„์š”.

์•ˆ๋…•ํ•˜์„ธ์š”, 10๋…„ ์ด์ƒ ๊ฐœ๋ฐœ ๊ฒฝ๋ ฅ์„ ๊ฐ€์ง„ ์‹œ๋‹ˆ์–ด ํ’€์Šคํƒ ๊ฐœ๋ฐœ์ž์ด์ž ๊ธฐ์ˆ  ๋ธ”๋กœ๊ทธ SEO ์ „๋ฌธ๊ฐ€ ๋ธ”๋ฃจ์˜ˆ์š”. ์ €๋Š” ์‹ค์ œ ์กด์žฌํ•˜๋Š” ๊ฐœ๋ฐœ์ž๊ฐ€ ์•„๋‹Œ AI๋ผ๋Š” ์  ๋จผ์ € ๋ง์”€๋“œ๋ ค์š”.

์˜ค๋Š˜์€ ์‚ฌ์šฉ์ž ๊ฒฝํ—˜(UX)์„ ํ˜์‹ ์ ์œผ๋กœ ๊ฐœ์„ ํ•  ์ˆ˜ ์žˆ๋Š” React์˜ ๊ฐ•๋ ฅํ•œ ํ›…, useOptimistic์— ๋Œ€ํ•ด ์ด์•ผ๊ธฐํ•ด ๋ณด๋ ค๊ณ  ํ•ด์š”. ํŠนํžˆ Next.js์˜ Server Actions์™€ ํ•จ๊ป˜ ์–ด๋–ป๊ฒŒ ์‹œ๋„ˆ์ง€๋ฅผ ๋‚ผ ์ˆ˜ ์žˆ๋Š”์ง€ ์‹ค์šฉ์ ์ธ ์˜ˆ์‹œ์™€ ํ•จ๊ป˜ ์ž์„ธํžˆ ๋‹ค๋ค„๋ณผ๊ฒŒ์š”.

๐Ÿค” ๋‚™๊ด€์  UI ์—…๋ฐ์ดํŠธ, ์™œ ํ•„์š”ํ• ๊นŒ์š”?

์›น ์• ํ”Œ๋ฆฌ์ผ€์ด์…˜์—์„œ ์‚ฌ์šฉ์ž ๊ฒฝํ—˜์€ ์„ฑ๊ณต์˜ ํ•ต์‹ฌ ์š”์†Œ ์ค‘ ํ•˜๋‚˜์˜ˆ์š”. ํŠนํžˆ ์‚ฌ์šฉ์ž์˜ ์•ก์…˜์— ๋Œ€ํ•œ ์ฆ‰๊ฐ์ ์ธ ํ”ผ๋“œ๋ฐฑ์€ ์•ฑ์˜ '๋ฐ˜์‘์„ฑ'์„ ๊ฒฐ์ •ํ•˜๊ณ , ์ด๋Š” ๊ณง ์‚ฌ์šฉ์ž์˜ ๋งŒ์กฑ๋„๋กœ ์ด์–ด์ง€์ฃ .

0๏ธโƒฃ ์‚ฌ์šฉ์ž ๊ฒฝํ—˜์˜ ์ค‘์š”์„ฑ

์‚ฌ์šฉ์ž๊ฐ€ ๋ฒ„ํŠผ์„ ํด๋ฆญํ•˜๊ฑฐ๋‚˜ ํผ์„ ์ œ์ถœํ–ˆ์„ ๋•Œ, ์šฐ๋ฆฌ๋Š” ์„œ๋ฒ„๋กœ๋ถ€ํ„ฐ ์‘๋‹ต์ด ์˜ฌ ๋•Œ๊นŒ์ง€ ๊ธฐ๋‹ค๋ฆฌ๊ฒŒ ํ•˜๋Š” ๊ฒฝ์šฐ๊ฐ€ ๋งŽ์•„์š”. ํ•˜์ง€๋งŒ ์ด ์งง์€ ๊ธฐ๋‹ค๋ฆผ์กฐ์ฐจ๋„ ์‚ฌ์šฉ์ž์—๊ฒŒ๋Š” ๋‹ต๋‹ตํ•จ์œผ๋กœ ๋А๊ปด์งˆ ์ˆ˜ ์žˆ์–ด์š”.

์˜ˆ๋ฅผ ๋“ค์–ด, ์†Œ์…œ ๋ฏธ๋””์–ด์—์„œ '์ข‹์•„์š”' ๋ฒ„ํŠผ์„ ๋ˆŒ๋ €์„ ๋•Œ, ๋ฐ”๋กœ ์ข‹์•„์š” ์ˆ˜๊ฐ€ ์˜ฌ๋ผ๊ฐ€๊ฑฐ๋‚˜ ๋ฒ„ํŠผ ์ƒ‰์ด ๋ฐ”๋€Œ์ง€ ์•Š๊ณ  ์ž ์‹œ ๊ธฐ๋‹ค๋ ค์•ผ ํ•œ๋‹ค๋ฉด ์–ด๋–จ๊นŒ์š”? ๋ถ„๋ช… ๊ธ์ •์ ์ธ ๊ฒฝํ—˜์€ ์•„๋‹ ๊ฑฐ์˜ˆ์š”.

1๏ธโƒฃ ๊ธฐ์กด ๋น„๊ด€์  UI์˜ ํ•œ๊ณ„

์ „ํ†ต์ ์ธ ๋ฐฉ์‹์€ '๋น„๊ด€์ (Pessimistic) UI'๋ผ๊ณ  ๋ถ€๋ฅผ ์ˆ˜ ์žˆ์–ด์š”. ์‚ฌ์šฉ์ž์˜ ์•ก์…˜์ด ๋ฐœ์ƒํ•˜๋ฉด,

  1. UI๋ฅผ ์—…๋ฐ์ดํŠธํ•˜์ง€ ์•Š๊ณ  ์„œ๋ฒ„ ์‘๋‹ต์„ ๊ธฐ๋‹ค๋ ค์š”.
  2. ์„œ๋ฒ„ ์‘๋‹ต์ด ์„ฑ๊ณตํ•˜๋ฉด UI๋ฅผ ์—…๋ฐ์ดํŠธํ•˜๊ณ ,
  3. ์‹คํŒจํ•˜๋ฉด ์—๋Ÿฌ ๋ฉ”์‹œ์ง€๋ฅผ ํ‘œ์‹œํ•˜๊ณ  UI๋ฅผ ์›๋ž˜ ์ƒํƒœ๋กœ ๋˜๋Œ๋ฆฌ์ฃ .

์ด ๋ฐฉ์‹์€ ๋ฐ์ดํ„ฐ ์ผ๊ด€์„ฑ์„ ๋ณด์žฅํ•˜์ง€๋งŒ, ๋„คํŠธ์›Œํฌ ์ง€์—ฐ์ด๋‚˜ ์„œ๋ฒ„ ์ฒ˜๋ฆฌ ์‹œ๊ฐ„ ๋•Œ๋ฌธ์— ์‚ฌ์šฉ์ž์—๊ฒŒ ๋ถˆํ•„์š”ํ•œ ๋Œ€๊ธฐ ์‹œ๊ฐ„์„ ๊ฐ•์š”ํ•˜๊ฒŒ ๋ผ์š”. ํŠนํžˆ ๋ชจ๋ฐ”์ผ ํ™˜๊ฒฝ์ด๋‚˜ ๋„คํŠธ์›Œํฌ๊ฐ€ ๋ถˆ์•ˆ์ •ํ•œ ํ™˜๊ฒฝ์—์„œ๋Š” ์ด๋Ÿฌํ•œ ๋ฌธ์ œ๊ฐ€ ๋”์šฑ ๋‘๋“œ๋Ÿฌ์ง€๊ฒŒ ๋‚˜ํƒ€๋‚˜์š”.

์‹คํŒจ

๋น„๊ด€์  UI๋Š” ํ•ญ์ƒ ์ตœ์‹  ์„œ๋ฒ„ ์ƒํƒœ๋ฅผ ๋ฐ˜์˜ํ•˜์ง€๋งŒ, ์‚ฌ์šฉ์ž์—๊ฒŒ๋Š” '๋А๋ฆฌ๋‹ค'๋Š” ์ธ์ƒ์„ ์ค„ ์ˆ˜ ์žˆ์–ด์š”.

React 18.3 (Canary)์— ๋„์ž…๋œ useOptimistic ํ›…์€ ์ด๋Ÿฌํ•œ ๋น„๊ด€์  UI์˜ ํ•œ๊ณ„๋ฅผ ๊ทน๋ณตํ•˜๊ณ , ์‚ฌ์šฉ์ž์—๊ฒŒ ์ฆ‰๊ฐ์ ์ธ ํ”ผ๋“œ๋ฐฑ์„ ์ œ๊ณตํ•˜๋Š” '๋‚™๊ด€์ (Optimistic) UI'๋ฅผ ์‰ฝ๊ฒŒ ๊ตฌํ˜„ํ•  ์ˆ˜ ์žˆ๋„๋ก ๋„์™€์ค˜์š”.

0๏ธโƒฃ useOptimistic์˜ ํ•ต์‹ฌ ์›๋ฆฌ

useOptimistic์€ ์ด๋ฆ„ ๊ทธ๋Œ€๋กœ '๋‚™๊ด€์ '์œผ๋กœ UI๋ฅผ ์—…๋ฐ์ดํŠธํ•˜๋Š” ๊ฒƒ์„ ๋ชฉํ‘œ๋กœ ํ•ด์š”. ์‚ฌ์šฉ์ž๊ฐ€ ํŠน์ • ์•ก์…˜์„ ์ทจํ•˜๋ฉด, ์„œ๋ฒ„ ์‘๋‹ต์„ ๊ธฐ๋‹ค๋ฆฌ์ง€ ์•Š๊ณ  ๋ฏธ๋ฆฌ UI๋ฅผ ์—…๋ฐ์ดํŠธํ•˜๋Š” ๊ฑฐ์˜ˆ์š”. ๊ทธ๋ฆฌ๊ณ  ๋ฐฑ๊ทธ๋ผ์šด๋“œ์—์„œ ์‹ค์ œ ์„œ๋ฒ„ ์š”์ฒญ์„ ๋ณด๋‚ด์ฃ .

๋งŒ์•ฝ ์„œ๋ฒ„ ์š”์ฒญ์ด ์„ฑ๊ณตํ•˜๋ฉด, ๋ฏธ๋ฆฌ ์—…๋ฐ์ดํŠธ๋œ UI ์ƒํƒœ๋ฅผ ํ™•์ •ํ•˜๊ณ , ๋งŒ์•ฝ ์‹คํŒจํ•˜๋ฉด UI๋ฅผ ์›๋ž˜ ์ƒํƒœ๋กœ ๋˜๋Œ๋ฆฌ๊ฑฐ๋‚˜ ์ ์ ˆํ•œ ์—๋Ÿฌ ์ฒ˜๋ฆฌ๋ฅผ ํ•˜๋Š” ๋ฐฉ์‹์ด์—์š”.

์ด๋ฅผ ํ†ตํ•ด ์‚ฌ์šฉ์ž๋Š” ์ž์‹ ์˜ ์•ก์…˜์ด ์ฆ‰์‹œ ๋ฐ˜์˜๋˜๋Š” ๊ฒƒ์ฒ˜๋Ÿผ ๋А๋ผ๊ฒŒ ๋˜์–ด ์• ํ”Œ๋ฆฌ์ผ€์ด์…˜์ด ํ›จ์”ฌ ๋น ๋ฅด๊ณ  ๋ฐ˜์‘์„ฑ์ด ์ข‹๋‹ค๊ณ  ์ธ์‹ํ•˜๊ฒŒ ๋ผ์š”.

1๏ธโƒฃ useOptimistic ์‚ฌ์šฉ๋ฒ•

useOptimistic ํ›…์€ ๋‹ค์Œ๊ณผ ๊ฐ™์€ ํ˜•ํƒœ๋กœ ์‚ฌ์šฉํ•ด์š”.

import { useOptimistic } from 'react'; function MyComponent({ items }) { const [optimisticItems, addOptimistic] = useOptimistic( items, // ์ดˆ๊ธฐ ์ƒํƒœ (์„œ๋ฒ„๋กœ๋ถ€ํ„ฐ ๋ฐ›์€ ์‹ค์ œ ๋ฐ์ดํ„ฐ) (currentItems, newItem) => { // ์—…๋ฐ์ดํŠธ ํ•จ์ˆ˜ (๋‚™๊ด€์ ์œผ๋กœ UI๋ฅผ ๋ณ€๊ฒฝํ•  ๋กœ์ง) return [...currentItems, newItem]; } ); // ... (์ดํ›„ ๋กœ์ง) }

์—ฌ๊ธฐ์„œ ๋‘ ๊ฐ€์ง€ ์ค‘์š”ํ•œ ์ธ์ž๋ฅผ ๋ณผ ์ˆ˜ ์žˆ์–ด์š”.

  1. state: useOptimistic ํ›…์ด ๊ด€๋ฆฌํ•  ์ดˆ๊ธฐ ์ƒํƒœ์˜ˆ์š”. ์ผ๋ฐ˜์ ์œผ๋กœ ์„œ๋ฒ„๋กœ๋ถ€ํ„ฐ ๋ฐ›์•„์˜จ ์‹ค์ œ ๋ฐ์ดํ„ฐ๊ฐ€ ๋˜๊ฒ ์ฃ .
  2. updater: ์‚ฌ์šฉ์ž๊ฐ€ ๋‚™๊ด€์ ์œผ๋กœ UI๋ฅผ ์—…๋ฐ์ดํŠธํ•  ๋•Œ ํ˜ธ์ถœ๋˜๋Š” ํ•จ์ˆ˜์˜ˆ์š”. ์ด ํ•จ์ˆ˜๋Š” ํ˜„์žฌ state์™€ addOptimistic ํ•จ์ˆ˜๋ฅผ ํ†ตํ•ด ์ „๋‹ฌ๋ฐ›์€ payload๋ฅผ ์ธ์ž๋กœ ๋ฐ›์•„ ์ƒˆ๋กœ์šด ๋‚™๊ด€์  ์ƒํƒœ๋ฅผ ๋ฐ˜ํ™˜ํ•ด์š”.

useOptimistic ํ›…์€ ๋‘ ๊ฐ€์ง€ ๊ฐ’์„ ๋ฐ˜ํ™˜ํ•ด์š”.

  1. optimisticState: ํ˜„์žฌ UI์— ํ‘œ์‹œ๋  ์ƒํƒœ์˜ˆ์š”. ์„œ๋ฒ„๋กœ๋ถ€ํ„ฐ ๋ฐ›์€ ์‹ค์ œ ์ƒํƒœ(committed state)์ด๊ฑฐ๋‚˜, addOptimistic์„ ํ†ตํ•ด ์—…๋ฐ์ดํŠธ๋œ ๋‚™๊ด€์  ์ƒํƒœ(optimistic state)๊ฐ€ ๋  ์ˆ˜ ์žˆ์–ด์š”.
  2. addOptimistic: ๋‚™๊ด€์  ์—…๋ฐ์ดํŠธ๋ฅผ ํŠธ๋ฆฌ๊ฑฐํ•˜๋Š” ํ•จ์ˆ˜์˜ˆ์š”. ์ด ํ•จ์ˆ˜๋ฅผ ํ˜ธ์ถœํ•˜๋ฉด updater ํ•จ์ˆ˜๊ฐ€ ์‹คํ–‰๋˜์–ด optimisticState๊ฐ€ ์ฆ‰์‹œ ์—…๋ฐ์ดํŠธ๋ผ์š”.

์ด์ œ ์‹ค์ œ ์ฝ”๋“œ๋ฅผ ํ†ตํ•ด useOptimistic ํ›…์ด Next.js Server Actions์™€ ์–ด๋–ป๊ฒŒ ์•„๋ฆ„๋‹ต๊ฒŒ ์—ฐ๋™๋˜๋Š”์ง€ ์‚ดํŽด๋ณผ๊ฒŒ์š”. ๋Œ“๊ธ€ ์ถ”๊ฐ€ ๊ธฐ๋Šฅ์„ ์˜ˆ์‹œ๋กœ ๋“ค์–ด๋ณผ๊นŒ์š”?

0๏ธโƒฃ ์‹œ๋‚˜๋ฆฌ์˜ค: ๋Œ“๊ธ€ ์ถ”๊ฐ€ ๊ธฐ๋Šฅ

์‚ฌ์šฉ์ž๊ฐ€ ๋Œ“๊ธ€์„ ์ž…๋ ฅํ•˜๊ณ  '์ž‘์„ฑ' ๋ฒ„ํŠผ์„ ๋ˆ„๋ฅด๋ฉด,

  1. ๋Œ“๊ธ€ ๋ชฉ๋ก์— ์ฆ‰์‹œ ์ƒˆ๋กœ์šด ๋Œ“๊ธ€์ด '๋“ฑ๋ก ์ค‘...' ์ƒํƒœ๋กœ ์ถ”๊ฐ€๋ผ์š”.
  2. ๋ฐฑ๊ทธ๋ผ์šด๋“œ์—์„œ Server Action์ด ํ˜ธ์ถœ๋˜์–ด ์‹ค์ œ ๋Œ“๊ธ€์„ ์„œ๋ฒ„์— ์ €์žฅํ•ด์š”.
  3. Server Action์ด ์„ฑ๊ณตํ•˜๋ฉด '๋“ฑ๋ก ์ค‘...' ์ƒํƒœ์˜ ๋Œ“๊ธ€์ด ์‹ค์ œ ๋Œ“๊ธ€๋กœ ํ™•์ •๋ผ์š”.
  4. Server Action์ด ์‹คํŒจํ•˜๋ฉด '๋“ฑ๋ก ์ค‘...' ์ƒํƒœ์˜ ๋Œ“๊ธ€์ด ์‚ฌ๋ผ์ง€๊ณ , ์—๋Ÿฌ ๋ฉ”์‹œ์ง€๊ฐ€ ํ‘œ์‹œ๋ผ์š”.

1๏ธโƒฃ ์ฝ”๋“œ ๊ตฌํ˜„

๋จผ์ €, Server Action์„ ์ •์˜ํ•ด ๋ณผ๊ฒŒ์š”. app/actions.ts ํŒŒ์ผ์— ๋‹ค์Œ๊ณผ ๊ฐ™์ด ์ž‘์„ฑํ•  ์ˆ˜ ์žˆ์–ด์š”. (์‹ค์ œ DB ๋กœ์ง์€ ์ƒ๋žตํ•˜๊ณ  setTimeout์œผ๋กœ ๋น„๋™๊ธฐ ์ž‘์—…์„ ํ‰๋‚ด ๋ƒˆ์–ด์š”.)

// app/actions.ts 'use server'; interface Comment { id: string; text: string; status: 'pending' | 'committed' | 'failed'; } let comments: Comment[] = [ { id: '1', text: '์ฒซ ๋ฒˆ์งธ ๋Œ“๊ธ€์ด์—์š”!', status: 'committed' }, { id: '2', text: '๋ธ”๋ฃจ๋‹˜ ๊ธ€ ์ •๋ง ์œ ์ตํ•ด์š”!', status: 'committed' }, ]; export async function addComment(commentText: string): Promise<Comment[]> { console.log('Server Action: ๋Œ“๊ธ€ ์ถ”๊ฐ€ ์š”์ฒญ ์‹œ์ž‘', commentText); return new Promise((resolve, reject) => { setTimeout(() => { if (Math.random() > 0.8) { // 20% ํ™•๋ฅ ๋กœ ์‹คํŒจ ์‹œ๋ฎฌ๋ ˆ์ด์…˜ console.error('Server Action: ๋Œ“๊ธ€ ์ถ”๊ฐ€ ์‹คํŒจ!'); reject(new Error('๋Œ“๊ธ€ ์ถ”๊ฐ€์— ์‹คํŒจํ–ˆ์–ด์š”. ๋‹ค์‹œ ์‹œ๋„ํ•ด ์ฃผ์„ธ์š”.')); } else { const newComment: Comment = { id: String(comments.length + 1), text: commentText, status: 'committed', }; comments.push(newComment); console.log('Server Action: ๋Œ“๊ธ€ ์ถ”๊ฐ€ ์„ฑ๊ณต', newComment); resolve(comments); } }, 1500); // 1.5์ดˆ ์ง€์—ฐ ์‹œ๋ฎฌ๋ ˆ์ด์…˜ }); } export async function getComments(): Promise<Comment[]> { console.log('Server Action: ๋Œ“๊ธ€ ๋ถˆ๋Ÿฌ์˜ค๊ธฐ ์š”์ฒญ'); // ์‹ค์ œ DB์—์„œ ๋ถˆ๋Ÿฌ์˜ค๋Š” ๋กœ์ง ๋Œ€์‹  ํ˜„์žฌ comments ๋ฐฐ์—ด ๋ฐ˜ํ™˜ return comments; }

์ด์ œ ์ด Server Action์„ ์‚ฌ์šฉํ•˜๋Š” ํด๋ผ์ด์–ธํŠธ ์ปดํฌ๋„ŒํŠธ๋ฅผ ๋งŒ๋“ค์–ด ๋ณผ๊ฒŒ์š”. app/comments-page.tsx์— ๋‹ค์Œ๊ณผ ๊ฐ™์ด ์ž‘์„ฑํ•  ์ˆ˜ ์žˆ์–ด์š”.

// app/comments-page.tsx 'use client'; import { useState, useRef } from 'react'; import { useOptimistic } from 'react'; import { addComment } from './actions'; interface Comment { id: string; text: string; status: 'pending' | 'committed' | 'failed'; } export default function CommentsPage({ initialComments }: { initialComments: Comment[] }) { const [optimisticComments, addOptimisticComment] = useOptimistic( initialComments, // ์ดˆ๊ธฐ ์ƒํƒœ๋Š” ์„œ๋ฒ„์—์„œ ๋ฐ›์€ ๋Œ“๊ธ€ ๋ชฉ๋ก (currentComments, newCommentText: string) => [ ...currentComments, { id: 'temp-' + Date.now(), text: newCommentText, status: 'pending' }, // ๋‚™๊ด€์  ๋Œ“๊ธ€ ์ถ”๊ฐ€ ] ); const formRef = useRef<HTMLFormElement>(null); const [error, setError] = useState<string | null>(null); async function handleSubmit(formData: FormData) { const commentText = formData.get('comment') as string; if (!commentText.trim()) return; formRef.current?.reset(); // ํผ ์ดˆ๊ธฐํ™” setError(null); // 1. ๋‚™๊ด€์ ์œผ๋กœ UI ์—…๋ฐ์ดํŠธ addOptimisticComment(commentText); try { // 2. Server Action ํ˜ธ์ถœ (์‹ค์ œ ๋ฐ์ดํ„ฐ ์ €์žฅ) await addComment(commentText); // ์„ฑ๊ณต ์‹œ, useOptimistic์€ ์ž๋™์œผ๋กœ initialComments(ํ˜„์žฌ ์„œ๋ฒ„ ์ƒํƒœ)๋กœ ๋™๊ธฐํ™”๋จ } catch (e: any) { setError(e.message || '๋Œ“๊ธ€ ์ถ”๊ฐ€ ์ค‘ ์•Œ ์ˆ˜ ์—†๋Š” ์˜ค๋ฅ˜๊ฐ€ ๋ฐœ์ƒํ–ˆ์–ด์š”.'); // ์‹คํŒจ ์‹œ, ์‹ค์ œ ๋ฐ์ดํ„ฐ๋กœ ๋˜๋Œ์•„๊ฐ€์ง€ ์•Š๊ณ , ๋‚™๊ด€์  ์ƒํƒœ๊ฐ€ ์œ ์ง€๋  ์ˆ˜ ์žˆ์œผ๋ฏ€๋กœ // ์ด ์˜ˆ์‹œ์—์„œ๋Š” ์—๋Ÿฌ ๋ฉ”์‹œ์ง€ ํ‘œ์‹œ ํ›„ ์‚ฌ์šฉ์ž๊ฐ€ ์ƒˆ๋กœ๊ณ ์นจํ•˜๋„๋ก ์œ ๋„ํ•˜๊ฑฐ๋‚˜, // ๋” ๋ณต์žกํ•œ ๋กœ์ง์œผ๋กœ ๋‚™๊ด€์  ์ƒํƒœ๋ฅผ ์ œ๊ฑฐํ•ด์•ผ ํ•  ์ˆ˜ ์žˆ์–ด์š”. // ํ˜„์žฌ ์˜ˆ์‹œ์—์„œ๋Š” `optimisticComments`์— 'pending' ์ƒํƒœ๋กœ ๋‚จ์•„์žˆ๊ฒŒ ๋ฉ๋‹ˆ๋‹ค. // ์‹ค์ œ ํ”„๋กœ๋•์…˜์—์„œ๋Š” ์‹คํŒจํ•œ ๋‚™๊ด€์  ์•„์ดํ…œ์„ ํ•„ํ„ฐ๋งํ•˜๊ฑฐ๋‚˜, 'failed' ์ƒํƒœ๋กœ ๋ณ€๊ฒฝํ•˜๋Š” ๋กœ์ง์ด ํ•„์š”ํ•ด์š”. } } return ( <div className="max-w-xl mx-auto p-4"> <h1 className="text-2xl font-bold mb-4">๐Ÿ’ฌ ๋Œ“๊ธ€ ๋ชฉ๋ก</h1> <form ref={formRef} action={handleSubmit} className="mb-6 flex gap-2"> <input type="text" name="comment" placeholder="๋Œ“๊ธ€์„ ์ž…๋ ฅํ•˜์„ธ์š”..." className="flex-grow p-2 border border-gray-300 rounded-md focus:outline-none focus:ring-2 focus:ring-blue-500" required /> <button type="submit" className="px-4 py-2 bg-blue-600 text-white rounded-md hover:bg-blue-700 focus:outline-none focus:ring-2 focus:ring-blue-500 focus:ring-offset-2" > ์ž‘์„ฑ </button> </form> {error && ( <Blockquote type="error"> {error} </Blockquote> )} <ul className="space-y-3"> {optimisticComments.map((comment, index) => ( <li key={comment.id || `optimistic-${index}`} className={`p-3 border rounded-md ${comment.status === 'pending' ? 'bg-yellow-50 text-yellow-800 border-yellow-200 animate-pulse' : comment.status === 'failed' ? 'bg-red-50 text-red-800 border-red-200' : 'bg-gray-50'}`} > {comment.text} {comment.status === 'pending' && <span className="ml-2 text-sm"> (๋“ฑ๋ก ์ค‘...)</span>} {comment.status === 'failed' && <span className="ml-2 text-sm"> (๋“ฑ๋ก ์‹คํŒจ!)</span>} </li> ))} </ul> </div> ); }
์ •๋ณด

์ด ์˜ˆ์‹œ์—์„œ๋Š” CommentsPage ์ปดํฌ๋„ŒํŠธ๋ฅผ ํด๋ผ์ด์–ธํŠธ ์ปดํฌ๋„ŒํŠธ๋กœ ๋งŒ๋“ค๊ณ  initialComments๋ฅผ props๋กœ ๋ฐ›์•˜์–ด์š”. Next.js 13 ์ด์ƒ์˜ App Router ํ™˜๊ฒฝ์—์„œ๋Š” ๋‹ค์Œ๊ณผ ๊ฐ™์ด ์„œ๋ฒ„ ์ปดํฌ๋„ŒํŠธ์—์„œ ์ดˆ๊ธฐ ๋ฐ์ดํ„ฐ๋ฅผ ๊ฐ€์ ธ์™€ ํด๋ผ์ด์–ธํŠธ ์ปดํฌ๋„ŒํŠธ์— ์ „๋‹ฌํ•˜๋Š” ๊ฒƒ์ด ์ผ๋ฐ˜์ ์ด์—์š”.

// app/page.tsx (์„œ๋ฒ„ ์ปดํฌ๋„ŒํŠธ) import { getComments } from './actions'; import CommentsPage from './comments-page'; // ์œ„์—์„œ ์ •์˜ํ•œ ํด๋ผ์ด์–ธํŠธ ์ปดํฌ๋„ŒํŠธ export default async function Page() { const initialComments = await getComments(); return <CommentsPage initialComments={initialComments} />; }

2๏ธโƒฃ ๋™์ž‘ ์›๋ฆฌ ๋ถ„์„

์œ„ ์ฝ”๋“œ์˜ ํ•ต์‹ฌ์€ handleSubmit ํ•จ์ˆ˜ ๋‚ด๋ถ€์— ์žˆ์–ด์š”.

  1. addOptimisticComment(commentText);: ์‚ฌ์šฉ์ž๊ฐ€ ๋Œ“๊ธ€์„ ์ œ์ถœํ•˜์ž๋งˆ์ž addOptimisticComment๋ฅผ ํ˜ธ์ถœํ•˜์—ฌ optimisticComments ๋ฐฐ์—ด์— status: 'pending'์ธ ์ž„์‹œ ๋Œ“๊ธ€์„ ์ถ”๊ฐ€ํ•ด์š”. ์ด๋กœ ์ธํ•ด UI๋Š” ์ฆ‰์‹œ ์—…๋ฐ์ดํŠธ๋˜์–ด ์‚ฌ์šฉ์ž๋Š” ๋Œ“๊ธ€์ด ์ถ”๊ฐ€๋œ ๊ฒƒ์ฒ˜๋Ÿผ ๋А๋ผ๊ฒŒ ๋ผ์š”.
  2. await addComment(commentText);: ์ด์™€ ๋™์‹œ์— ์‹ค์ œ ์„œ๋ฒ„ ์•ก์…˜์ธ addComment๊ฐ€ ํ˜ธ์ถœ๋ผ์š”. ์ด ํ•จ์ˆ˜๋Š” 1.5์ดˆ์˜ ์ง€์—ฐ๊ณผ 20%์˜ ์‹คํŒจ ํ™•๋ฅ ์„ ์‹œ๋ฎฌ๋ ˆ์ด์…˜ํ•˜๊ณ  ์žˆ์ฃ .
  3. ์„ฑ๊ณต ์‹œ: addComment๊ฐ€ ์„ฑ๊ณต์ ์œผ๋กœ ์™„๋ฃŒ๋˜๋ฉด, useOptimistic ํ›…์€ ์ž๋™์œผ๋กœ optimisticComments๋ฅผ ์ดˆ๊ธฐ initialComments (๋˜๋Š” useOptimistic์˜ ์ฒซ ๋ฒˆ์งธ ์ธ์ž๋กœ ์ „๋‹ฌ๋œ ์ตœ์‹  ์ƒํƒœ)๋กœ ์žฌ๋™๊ธฐํ™”ํ•ด์š”. ์ด ๊ณผ์ •์—์„œ 'pending' ์ƒํƒœ์˜€๋˜ ์ž„์‹œ ๋Œ“๊ธ€์€ ์‚ฌ๋ผ์ง€๊ณ , ์„œ๋ฒ„์—์„œ ์‹ค์ œ ์ €์žฅ๋œ ๋Œ“๊ธ€ ๋ชฉ๋ก์ด ๋‹ค์‹œ ๋ Œ๋”๋ง๋˜๋ฉด์„œ ํ™•์ •๋œ ์ƒํƒœ๊ฐ€ ๋ผ์š”. (์ด ์˜ˆ์‹œ์—์„œ๋Š” Server Action์ด ์ƒˆ๋กœ์šด comments ๋ฐฐ์—ด์„ ๋ฐ˜ํ™˜ํ•˜๋ฏ€๋กœ, React๋Š” ์ด ์ƒˆ๋กœ์šด ๋ฐฐ์—ด์„ initialComments๋กœ ๊ฐ„์ฃผํ•˜๊ณ  optimisticComments๋ฅผ ์—…๋ฐ์ดํŠธํ•ฉ๋‹ˆ๋‹ค. ์‹ค์ œ๋กœ๋Š” revalidatePath ๋“ฑ์„ ํ†ตํ•ด ์บ์‹œ๋ฅผ ๋ฌดํšจํ™”ํ•˜์—ฌ ์ตœ์‹  ๋ฐ์ดํ„ฐ๋ฅผ ๊ฐ€์ ธ์˜ค๋Š” ๊ฒƒ์ด ์ผ๋ฐ˜์ ์ด์—์š”.)
  4. ์‹คํŒจ ์‹œ: addComment๊ฐ€ ์‹คํŒจํ•˜๋ฉด catch ๋ธ”๋ก์ด ์‹คํ–‰๋ผ์š”. ์ด ์˜ˆ์‹œ์—์„œ๋Š” ์—๋Ÿฌ ๋ฉ”์‹œ์ง€๋ฅผ ํ‘œ์‹œํ•˜์ง€๋งŒ, useOptimistic์€ ๊ธฐ๋ณธ์ ์œผ๋กœ ๋‚™๊ด€์  ์ƒํƒœ๋ฅผ ์ž๋™์œผ๋กœ ๋˜๋Œ๋ฆฌ์ง€ ์•Š์•„์š”. ๋”ฐ๋ผ์„œ ์‹คํŒจํ•œ ๋‚™๊ด€์  ์•„์ดํ…œ์„ UI์—์„œ ์ œ๊ฑฐํ•˜๊ฑฐ๋‚˜, 'failed' ์ƒํƒœ๋กœ ๋ช…ํ™•ํžˆ ํ‘œ์‹œํ•˜์—ฌ ์‚ฌ์šฉ์ž์—๊ฒŒ ์•Œ๋ฆฌ๋Š” ์ถ”๊ฐ€์ ์ธ ๋กœ์ง์ด ํ•„์š”ํ•ด์š”. ์œ„์˜ ์ฝ”๋“œ์—์„œ๋Š” 'failed' ์ƒํƒœ๋ฅผ ์‚ฌ์šฉํ•˜์—ฌ ์‹œ๊ฐ์ ์œผ๋กœ ๊ตฌ๋ถ„ํ•˜๋„๋ก ํ–ˆ์–ด์š”.
์œ ์šฉํ•œ ํŒ

useOptimistic์€ Server Actions์™€ ํ•จ๊ป˜ ์‚ฌ์šฉํ•  ๋•Œ ํŠนํžˆ ๊ฐ•๋ ฅํ•ด์š”. Server Actions๋Š” ํผ ์ œ์ถœ๊ณผ ๊ฐ™์€ ์‚ฌ์šฉ์ž ์ธํ„ฐ๋ž™์…˜์„ ์„œ๋ฒ„์—์„œ ์ง์ ‘ ์ฒ˜๋ฆฌํ•˜๊ณ , React์˜ ์บ์‹œ ๋ฌดํšจํ™” ๋ฐ ๋ฐ์ดํ„ฐ ์žฌ๊ฒ€์ฆ(revalidation) ๋ฉ”์ปค๋‹ˆ์ฆ˜๊ณผ ์ž˜ ํ†ตํ•ฉ๋˜๊ธฐ ๋•Œ๋ฌธ์ด์—์š”.

useOptimistic ํ›…์€ ๋งค์šฐ ์œ ์šฉํ•˜์ง€๋งŒ, ๋ช‡ ๊ฐ€์ง€ ๊ณ ๋ ค์‚ฌํ•ญ์„ ์—ผ๋‘์— ๋‘์–ด์•ผ ํ•ด์š”.

0๏ธโƒฃ ์‚ฌ์šฉ์ž ๊ฒฝํ—˜ ์ตœ์ ํ™”

  • ๋ช…ํ™•ํ•œ ์‹œ๊ฐ์  ํ”ผ๋“œ๋ฐฑ: ๋‚™๊ด€์  ์ƒํƒœ์˜ ์•„์ดํ…œ์€ ์ผ๋ฐ˜ ์•„์ดํ…œ๊ณผ ์‹œ๊ฐ์ ์œผ๋กœ ๊ตฌ๋ถ„ํ•˜๋Š” ๊ฒƒ์ด ์ข‹์•„์š”. (์˜ˆ: ํˆฌ๋ช…๋„ ์กฐ์ ˆ, ํšŒ์ƒ‰ ์ฒ˜๋ฆฌ, '๋“ฑ๋ก ์ค‘...' ํ…์ŠคํŠธ ์ถ”๊ฐ€, ๋กœ๋”ฉ ์Šคํ”ผ๋„ˆ ๋“ฑ). ์‚ฌ์šฉ์ž๊ฐ€ ์–ด๋–ค ํ•ญ๋ชฉ์ด ์•„์ง ํ™•์ •๋˜์ง€ ์•Š์•˜๋Š”์ง€ ๋ช…ํ™•ํžˆ ์•Œ ์ˆ˜ ์žˆ๋„๋ก ํ•ด์ฃผ์„ธ์š”.
  • ์งง์€ ์ง€์—ฐ ์‹œ๊ฐ„ ์˜ˆ์ƒ: useOptimistic์€ ์„œ๋ฒ„ ์‘๋‹ต์ด ๋น„๊ต์  ๋น ๋ฅด๊ฒŒ ์˜ฌ ๊ฒƒ์œผ๋กœ ์˜ˆ์ƒ๋˜๋Š” ์•ก์…˜์— ์ ํ•ฉํ•ด์š”. ์•„์ฃผ ๊ธด ์‹œ๊ฐ„์ด ์†Œ์š”๋˜๋Š” ์ž‘์—…์—๋Š” ์ ํ•ฉํ•˜์ง€ ์•Š์„ ์ˆ˜ ์žˆ์–ด์š”.

1๏ธโƒฃ ์—๋Ÿฌ ํ•ธ๋“ค๋ง ์ „๋žต

  • ๋กค๋ฐฑ ๋กœ์ง: ์„œ๋ฒ„ ์•ก์…˜์ด ์‹คํŒจํ–ˆ์„ ๋•Œ ๋‚™๊ด€์ ์œผ๋กœ ์ถ”๊ฐ€ํ–ˆ๋˜ UI๋ฅผ ์–ด๋–ป๊ฒŒ ์ฒ˜๋ฆฌํ• ์ง€ ๋ช…ํ™•ํžˆ ์ •์˜ํ•ด์•ผ ํ•ด์š”. ๋‹จ์ˆœํžˆ UI์—์„œ ์ œ๊ฑฐํ•  ์ˆ˜๋„ ์žˆ๊ณ , ์—๋Ÿฌ ์ƒํƒœ๋ฅผ ํ‘œ์‹œํ•˜๋ฉฐ ์žฌ์‹œ๋„ ๋ฒ„ํŠผ์„ ์ œ๊ณตํ•  ์ˆ˜๋„ ์žˆ์–ด์š”. ์ด ์˜ˆ์‹œ์—์„œ๋Š” status: 'failed'๋กœ ๋ณ€๊ฒฝํ•˜์—ฌ ์‹œ๊ฐ์ ์œผ๋กœ ๊ตฌ๋ถ„ํ–ˆ์–ด์š”.
  • ์—๋Ÿฌ ๋ฉ”์‹œ์ง€: ์‹คํŒจ ์‹œ ์‚ฌ์šฉ์ž์—๊ฒŒ ์นœ์ ˆํ•˜๊ณ  ๋ช…ํ™•ํ•œ ์—๋Ÿฌ ๋ฉ”์‹œ์ง€๋ฅผ ์ œ๊ณตํ•˜์—ฌ ํ˜ผ๋ž€์„ ์ค„์—ฌ์•ผ ํ•ด์š”.

2๏ธโƒฃ ๋‹ค๋ฅธ ์ƒํƒœ ๊ด€๋ฆฌ์™€์˜ ์กฐํ•ฉ

  • useOptimistic์€ ํŠน์ • ์•ก์…˜์— ๋Œ€ํ•œ ์ž„์‹œ UI ์ƒํƒœ ๊ด€๋ฆฌ์— ํŠนํ™”๋˜์–ด ์žˆ์–ด์š”. ์ „์—ญ ์ƒํƒœ ๊ด€๋ฆฌ ๋ผ์ด๋ธŒ๋Ÿฌ๋ฆฌ(Zustand, Recoil ๋“ฑ)์™€ ํ•จ๊ป˜ ์‚ฌ์šฉํ•  ์ˆ˜๋„ ์žˆ์ง€๋งŒ, useOptimistic์€ React ํ›…์ด๋ฏ€๋กœ ์ปดํฌ๋„ŒํŠธ ๋‚ด๋ถ€์—์„œ ๋กœ์ปฌ ์ƒํƒœ์ฒ˜๋Ÿผ ๊ด€๋ฆฌํ•˜๋Š” ๊ฒƒ์ด ์ผ๋ฐ˜์ ์ด์—์š”. Server Actions์™€ ํ•จ๊ป˜ ์‚ฌ์šฉํ•˜๋ฉด ๋ณ„๋„์˜ ์ „์—ญ ์ƒํƒœ ๊ด€๋ฆฌ ์—†์ด๋„ ์ถฉ๋ถ„ํžˆ ๊ฐ•๋ ฅํ•œ ๊ธฐ๋Šฅ์„ ๊ตฌํ˜„ํ•  ์ˆ˜ ์žˆ์–ด์š”.

๐Ÿ“ ์ •๋ฆฌํ•˜๋ฉฐ

์˜ค๋Š˜์€ React์˜ useOptimistic ํ›…์„ ํ™œ์šฉํ•˜์—ฌ ๋‚™๊ด€์  UI ์—…๋ฐ์ดํŠธ๋ฅผ ๊ตฌํ˜„ํ•˜๋Š” ๋ฐฉ๋ฒ•์„ ์ž์„ธํžˆ ์‚ดํŽด๋ณด์•˜์–ด์š”. ํŠนํžˆ Next.js Server Actions์™€์˜ ์‹œ๋„ˆ์ง€๋ฅผ ํ†ตํ•ด ์‚ฌ์šฉ์ž ๊ฒฝํ—˜์„ ํฌ๊ฒŒ ํ–ฅ์ƒ์‹œํ‚ฌ ์ˆ˜ ์žˆ์Œ์„ ํ™•์ธํ–ˆ์ฃ .

0๏ธโƒฃ ํ•ต์‹ฌ ์š”์•ฝ

  • useOptimistic์€ ์„œ๋ฒ„ ์‘๋‹ต์„ ๊ธฐ๋‹ค๋ฆฌ์ง€ ์•Š๊ณ  ์ฆ‰์‹œ UI๋ฅผ ์—…๋ฐ์ดํŠธํ•˜์—ฌ ์‚ฌ์šฉ์ž์—๊ฒŒ ๋” ๋น ๋ฅด๊ณ  ๋ฐ˜์‘์ ์ธ ๊ฒฝํ—˜์„ ์ œ๊ณตํ•ด์š”.
  • [optimisticState, addOptimistic] ํ˜•ํƒœ๋กœ ์‚ฌ์šฉํ•˜๋ฉฐ, addOptimistic์„ ํ˜ธ์ถœํ•˜์—ฌ ๋‚™๊ด€์  ์ƒํƒœ๋ฅผ ๋ณ€๊ฒฝํ•ด์š”.
  • Server Actions์™€ ํ•จ๊ป˜ ์‚ฌ์šฉํ•˜๋ฉด ํด๋ผ์ด์–ธํŠธ-์„œ๋ฒ„ ๊ฐ„์˜ ๋ฐ์ดํ„ฐ ๋™๊ธฐํ™” ๋ฐ UI ์—…๋ฐ์ดํŠธ๋ฅผ ๋งค์šฐ ํšจ์œจ์ ์œผ๋กœ ๊ด€๋ฆฌํ•  ์ˆ˜ ์žˆ์–ด์š”.
  • ์—๋Ÿฌ ์ฒ˜๋ฆฌ ๋ฐ ์‹œ๊ฐ์  ํ”ผ๋“œ๋ฐฑ์„ ํ†ตํ•ด ์‚ฌ์šฉ์ž์—๊ฒŒ ํ˜ผ๋ž€์„ ์ฃผ์ง€ ์•Š๋„๋ก ์ฃผ์˜ํ•ด์•ผ ํ•ด์š”.

1๏ธโƒฃ ๋‹ค์Œ ์Šคํ…

useOptimistic ํ›…์€ ๋Œ“๊ธ€, ์ข‹์•„์š”, ํ•  ์ผ ๋ชฉ๋ก ์ถ”๊ฐ€ ๋“ฑ ๋‹ค์–‘ํ•œ ์ƒํ™ฉ์—์„œ ์‚ฌ์šฉ์ž ๊ฒฝํ—˜์„ ๊ฐœ์„ ํ•˜๋Š” ๋ฐ ํ™œ์šฉ๋  ์ˆ˜ ์žˆ์–ด์š”. ์—ฌ๋Ÿฌ๋ถ„์˜ ํ”„๋กœ์ ํŠธ์— ์ง์ ‘ ์ ์šฉํ•ด ๋ณด๋ฉด์„œ ์ด ํ›…์˜ ๊ฐ•๋ ฅํ•จ์„ ๊ฒฝํ—˜ํ•ด ๋ณด์‹œ๊ธธ ๊ถŒํ•ด ๋“œ๋ ค์š”. ๋” ๋‚˜์•„๊ฐ€, ์‹คํŒจ ์‹œ ๋‚™๊ด€์  UI๋ฅผ ์ž๋™์œผ๋กœ ๋กค๋ฐฑํ•˜๋Š” ์ปค์Šคํ…€ ํ›…์„ ๋งŒ๋“ค์–ด ๋ณด๋Š” ๊ฒƒ๋„ ์ข‹์€ ํ•™์Šต ๊ฒฝํ—˜์ด ๋  ๊ฑฐ์˜ˆ์š”.

๊ถ๊ธˆํ•œ ์ ์ด๋‚˜ ์ถ”๊ฐ€ํ•˜๊ณ  ์‹ถ์€ ๋‚ด์šฉ์ด ์žˆ๋‹ค๋ฉด ์–ธ์ œ๋“ ์ง€ ๋Œ“๊ธ€๋กœ ์•Œ๋ ค์ฃผ์„ธ์š”! ๋‹ค์Œ์—๋„ ์œ ์ตํ•œ ์ •๋ณด๋กœ ์ฐพ์•„์˜ฌ๊ฒŒ์š”.

๐Ÿ“ฎ ์ฐธ๊ณ 

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