Cache Components (Next.js 16+)

Enable Cache Components

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// next.config.ts
import type { NextConfig } from 'next'

const nextConfig: NextConfig = {
  cacheComponents: true,
}

export default nextConfig

Three Content Types

1. Static (Auto-Prerendered)

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export default function Page() {
  return (
    <header>
      <h1>Our Blog</h1>  {/* Static - instant */}
      <nav>...</nav>
    </header>
  )
}

2. Cached (use cache)

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async function BlogPosts() {
  'use cache'
  cacheLife('hours')

  const posts = await db.posts.findMany()
  return <PostList posts={posts} />
}

3. Dynamic (Suspense)

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import { Suspense } from 'react'

export default function Page() {
  return (
    <>
      <BlogPosts />  {/* Cached */}

      <Suspense fallback={<p>Loading...</p>}>
        <UserPreferences />  {/* Dynamic - streams in */}
      </Suspense>
    </>
  )
}

async function UserPreferences() {
  const theme = (await cookies()).get('theme')?.value
  return <p>Theme: {theme}</p>
}

use cache Directive

File Level

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'use cache'

export default async function Page() {
  // Entire page is cached
  const data = await fetchData()
  return <div>{data}</div>
}
`### Component Level`
export async function CachedComponent() {
  'use cache'
  const data = await fetchData()
  return <div>{data}</div>
}
`### Function Level`
export async function getData() {
  'use cache'
  return db.query('SELECT * FROM posts')
}

Cache Profiles

Built-in Profiles

cacheLife() - Custom Lifetime

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import { cacheLife } from 'next/cache'

async function getData() {
  'use cache'
  cacheLife('hours')  // Built-in profile
  return fetch('/api/data')
}

Inline Configuration

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async function getData() {
  'use cache'
  cacheLife({
    stale: 3600,      // 1 hour - serve stale while revalidating
    revalidate: 7200, // 2 hours - background revalidation interval
    expire: 86400,    // 1 day - hard expiration
  })
  return fetch('/api/data')
}

Cache Invalidation

cacheTag() - Tag Cached Content

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import { cacheTag } from 'next/cache'

async function getProducts() {
  'use cache'
  cacheTag('products')
  return db.products.findMany()
}

async function getProduct(id: string) {
  'use cache'
  cacheTag('products', `product-${id}`)
  return db.products.findUnique({ where: { id } })
}

updateTag() - Immediate Invalidation

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'use server'

import { updateTag } from 'next/cache'

export async function updateProduct(id: string, data: FormData) {
  await db.products.update({ where: { id }, data })
  updateTag(`product-${id}`)  // Immediate - same request sees fresh data
}

revalidateTag() - Background Revalidation

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'use server'

import { revalidateTag } from 'next/cache'

export async function createPost(data: FormData) {
  await db.posts.create({ data })
  revalidateTag('posts')  // Background - next request sees fresh data
}

Runtime Data Constraint

Solution: Pass as Arguments

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// Wrong - runtime API inside use cache
async function CachedProfile() {
  'use cache'
  const session = (await cookies()).get('session')?.value  // Error!
  return <div>{session}</div>
}

// Correct - extract outside, pass as argument
async function ProfilePage() {
  const session = (await cookies()).get('session')?.value
  return <CachedProfile sessionId={session} />
}

async function CachedProfile({ sessionId }: { sessionId: string }) {
  'use cache'
  // sessionId becomes part of cache key automatically
  const data = await fetchUserData(sessionId)
  return <div>{data.name}</div>
}

Exception: use cache: private

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async function getData() {
  'use cache: private'
  const session = (await cookies()).get('session')?.value  // Allowed
  return fetchData(session)
}

Cache Key Generation

• Build ID - invalidates all caches on deploy
• Function ID - hash of function location
• Serializable arguments - props become part of key
• Closure variables - outer scope values included

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async function Component({ userId }: { userId: string }) {
  const getData = async (filter: string) => {
    'use cache'
    // Cache key = userId (closure) + filter (argument)
    return fetch(`/api/users/${userId}?filter=${filter}`)
  }
  return getData('active')
}

Complete Example

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import { Suspense } from 'react'
import { cookies } from 'next/headers'
import { cacheLife, cacheTag } from 'next/cache'

export default function DashboardPage() {
  return (
    <>
      {/* Static shell - instant from CDN */}
      <header><h1>Dashboard</h1></header>
      <nav>...</nav>

      {/* Cached - fast, revalidates hourly */}
      <Stats />

      {/* Dynamic - streams in with fresh data */}
      <Suspense fallback={<NotificationsSkeleton />}>
        <Notifications />
      </Suspense>
    </>
  )
}

async function Stats() {
  'use cache'
  cacheLife('hours')
  cacheTag('dashboard-stats')

  const stats = await db.stats.aggregate()
  return <StatsDisplay stats={stats} />
}

async function Notifications() {
  const userId = (await cookies()).get('userId')?.value
  const notifications = await db.notifications.findMany({
    where: { userId, read: false }
  })
  return <NotificationList items={notifications} />
}

Migration from Previous Versions

Limitations

• Edge runtime not supported - requires Node.js
• Static export not supported - needs server
• Non-deterministic values (Math.random(), Date.now()) execute once at build time inside use cache

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import { connection } from 'next/server'

async function DynamicContent() {
  await connection()  // Defer to request time
  const id = crypto.randomUUID()  // Different per request
  return <div>{id}</div>
}

• Cache Components Guide
• use cache Directive