Next.js: Слои кеширования (request/data/full route) — пример кода

Question

Accepted Answer

Opt-in Data Cache (Next 15 default off), on-demand invalidation в Server Action, segment exports для force-dynamic и ISR.

## Пример

```ts
// Opt a fetch INTO the Data Cache (Next 15 default is off)
await fetch(url, { cache: 'force-cache' });                 // cache indefinitely
await fetch(url, { next: { revalidate: 3600 } });           // time-based: hourly
await fetch(url, { next: { tags: ['products'] } });         // taggable for on-demand
await fetch(url, { cache: 'no-store' });                    // never cache (dynamic)
```

```ts
// On-demand invalidation — the surgical tool, e.g. inside a Server Action
'use server';
import { revalidateTag, revalidatePath } from 'next/cache';
export async function publish() {
  await db.publish();
  revalidateTag('products');       // purge every fetch tagged 'products'
  revalidatePath('/dashboard');    // purge a specific route's Full Route Cache
}
```

```ts
// Force a whole segment's rendering/caching behaviour
export const dynamic = 'force-dynamic';   // no Full Route Cache, render every request
export const revalidate = 60;             // segment-level ISR window
export const fetchCache = 'force-cache';  // override per-fetch defaults for the segment
```

## Итог

Паттерн: tag fetch → mutate → `revalidateTag`; segment `revalidate` + fetch tags — точный контроль четырёх cache layers.