metaloozee/next-cache-components

Cache Components (Next.js 16+)

Cache Components enable Partial Prerendering (PPR) - mix static, cached, and dynamic content in a single route.

Enable Cache Components

// next.config.ts
import type { NextConfig } from "next";

const nextConfig: NextConfig = {
  cacheComponents: true,
};

export default nextConfig;

This replaces the old experimental.ppr flag.

---

Three Content Types

With Cache Components enabled, content falls into three categories:

1. Static (Auto-Prerendered)

Synchronous code, imports, pure computations - prerendered at build time:

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

2. Cached (use cache)

Async data that doesn't need fresh fetches every request:

async function BlogPosts() {
  "use cache";
  cacheLife("hours");

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

3. Dynamic (Suspense)

Runtime data that must be fresh - wrap in Suspense:

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

"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

"use cache"; // Default: 5m stale, 15m revalidate

"use cache: remote"; // Platform-provided cache (Redis, KV)

"use cache: private"; // For compliance, allows runtime APIs

cacheLife() - Custom Lifetime

import { cacheLife } from "next/cache";

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

Built-in profiles: 'default', 'minutes', 'hours', 'days', 'weeks', 'max'

Inline Configuration

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

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

Use when you need the cache refreshed within the same request:

"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

Use for stale-while-revalidate behavior:

"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

Cannot access cookies(), headers(), or searchParams inside use cache.

Solution: Pass as Arguments

// 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

For compliance requirements when you can't refactor:

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

---

Cache Key Generation

Cache keys are automatic based on:

• 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

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

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

| Old Config | Replacement | | --------------------------- | ---------------------------------- | | experimental.ppr | cacheComponents: true | | dynamic = 'force-dynamic' | Remove (default behavior) | | dynamic = 'force-static' | 'use cache' + cacheLife('max') | | revalidate = N | cacheLife({ revalidate: N }) | | unstable_cache() | 'use cache' directive |

---

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

For request-time randomness outside cache:

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>;
}

Sources:

• Cache Components Guide
• use cache Directive