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This PRs unifies the caching story across the docs, making Cache Components the happy path, while still providing guidance to users in the old model. However, instead of explaining the old model and its caching layers, we've created a new guide focusing on what APIs to use and when. This follow-up PR aligns terminology across the docs: https://github.com/vercel/next.js/pull/90589 ## IA updates Getting Started section: - Improves Getting Started progression: - **Before:** CC → Fetching Data → Updating Data → Caching and Revalidating (old and new model mixed) - **After:** Fetching Data (Dynamic) → Mutating Data (Dynamic) → Caching with CC (Prerendering) → Revalidating with CC. - New: `caching.mdx` (CC-first) - Structure: - Enabling Cache Components - Data vs UI-level caching - Working with request time APIs - Passing request values to cached functions - Working with non-deterministic operations - Working with synchronous operations - How rendering works (PPR and static shell story) - New: `revalidating.mdx` (CC-first) - Explains how to use `cacheLife` and `cacheTag` Guides Section: - New: `caching-and-revalidating.mdx` (Previous Model) - For users who are not using CC, includes `fetch` options and route segment config - Moves route segment config options that don't apply to CC from API reference to this guide (for easy archiving in the future). - New: `migrating-to-cache-components.mdx` (WIP) - Del: `caching.mdx` 😌 ## Terminology We should remove caching layers from the docs. Users only needed to be exposed to them when they were configured independently, but the new CC APIs work across layers. To make it easier to review this PR, I'm consolidating terminology and fixing broken links in a new PR: https://github.com/vercel/next.js/pull/90589 --------- Co-authored-by: Vercel <vercel[bot]@users.noreply.github.com> Co-authored-by: Joseph <[email protected]>
243 lines
6.9 KiB
Plaintext
243 lines
6.9 KiB
Plaintext
---
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title: useParams
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description: API Reference for the useParams hook in the Pages Router.
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---
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`useParams` is a hook that lets you read a route's [dynamic params](/docs/pages/building-your-application/routing/dynamic-routes) filled in by the current URL.
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```tsx filename="pages/shop/[slug].tsx" switcher
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import { useParams } from 'next/navigation'
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export default function ShopPage() {
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const params = useParams<{ slug: string }>()
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if (!params) {
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// Render fallback UI while params are not yet available
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return null
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}
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// Route -> /shop/[slug]
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// URL -> /shop/shoes
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// `params` -> { slug: 'shoes' }
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return <>Shop: {params.slug}</>
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}
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```
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```jsx filename="pages/shop/[slug].js" switcher
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import { useParams } from 'next/navigation'
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export default function ShopPage() {
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const params = useParams()
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if (!params) {
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// Render fallback UI while params are not yet available
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return null
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}
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// Route -> /shop/[slug]
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// URL -> /shop/shoes
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// `params` -> { slug: 'shoes' }
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return <>Shop: {params.slug}</>
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}
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```
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## Parameters
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```tsx
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const params = useParams()
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```
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`useParams` does not take any parameters.
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## Returns
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`useParams` returns an object containing the current route's filled in [dynamic parameters](/docs/pages/building-your-application/routing/dynamic-routes), or `null` during [prerendering](#behavior-during-prerendering).
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- Each property in the object is an active dynamic segment.
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- The property name is the segment's name, and the property value is what the segment is filled in with.
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- The property value will either be a `string` or array of `string`s depending on the [type of dynamic segment](/docs/pages/building-your-application/routing/dynamic-routes).
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- If the route contains no dynamic parameters, `useParams` returns an empty object.
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For example:
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| Route | URL | `useParams()` |
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| ---------------------------- | ----------- | ------------------------- |
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| `pages/shop/page.js` | `/shop` | `{}` |
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| `pages/shop/[slug].js` | `/shop/1` | `{ slug: '1' }` |
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| `pages/shop/[tag]/[item].js` | `/shop/1/2` | `{ tag: '1', item: '2' }` |
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| `pages/shop/[...slug].js` | `/shop/1/2` | `{ slug: ['1', '2'] }` |
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> **Good to know**: `useParams` is a [React Hook](https://react.dev/learn#using-hooks) and cannot be used with classes.
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## Behavior
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### Behavior during prerendering
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For pages that are [statically optimized](/docs/pages/building-your-application/rendering/automatic-static-optimization), `useParams` will return `null` on the initial render. After hydration, the value will be updated to the actual params once the router is ready.
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This is because params cannot be known during static generation for dynamic routes.
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```tsx filename="pages/shop/[slug].tsx" switcher
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import { useParams } from 'next/navigation'
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export default function ShopPage() {
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const params = useParams<{ slug: string }>()
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if (!params) {
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// Return a fallback UI while params are loading
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// This prevents hydration mismatches
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return <ShopPageSkeleton />
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}
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return <>Shop: {params.slug}</>
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}
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```
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```jsx filename="pages/shop/[slug].js" switcher
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import { useParams } from 'next/navigation'
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export default function ShopPage() {
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const params = useParams()
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if (!params) {
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// Return a fallback UI while params are loading
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// This prevents hydration mismatches
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return <ShopPageSkeleton />
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}
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return <>Shop: {params.slug}</>
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}
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```
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### Using with `getServerSideProps`
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When using [`getServerSideProps`](/docs/pages/building-your-application/data-fetching/get-server-side-props), the page is server-rendered on each request and `useParams` will return the actual params immediately:
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```tsx filename="pages/shop/[slug].tsx" switcher
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import { useParams } from 'next/navigation'
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export default function ShopPage() {
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const params = useParams<{ slug: string }>()
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// With getServerSideProps, this fallback is never rendered because
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// params is always available on the server. However, keeping
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// the fallback allows this component to be reused on other pages
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// that may not use getServerSideProps.
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if (!params) {
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return null
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}
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return <>Shop: {params.slug}</>
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}
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export async function getServerSideProps() {
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return { props: {} }
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}
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```
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```jsx filename="pages/shop/[slug].js" switcher
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import { useParams } from 'next/navigation'
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export default function ShopPage() {
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const params = useParams()
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// With getServerSideProps, this fallback is never rendered because
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// params is always available on the server. However, keeping
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// the fallback allows this component to be reused on other pages
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// that may not use getServerSideProps.
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if (!params) {
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return null
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}
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return <>Shop: {params.slug}</>
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}
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export async function getServerSideProps() {
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return { props: {} }
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}
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```
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### Comparison with `router.query`
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`useParams` only returns the dynamic route parameters, whereas [`router.query`](/docs/pages/api-reference/functions/use-router#router-object) from `useRouter` includes both dynamic parameters and query string parameters.
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```tsx filename="pages/shop/[slug].tsx" switcher
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import { useRouter } from 'next/router'
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import { useParams } from 'next/navigation'
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export default function ShopPage() {
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const router = useRouter()
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const params = useParams()
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// URL -> /shop/shoes?color=red
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// router.query -> { slug: 'shoes', color: 'red' }
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// params -> { slug: 'shoes' }
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// ...
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}
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```
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```jsx filename="pages/shop/[slug].js" switcher
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import { useRouter } from 'next/router'
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import { useParams } from 'next/navigation'
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export default function ShopPage() {
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const router = useRouter()
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const params = useParams()
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// URL -> /shop/shoes?color=red
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// router.query -> { slug: 'shoes', color: 'red' }
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// params -> { slug: 'shoes' }
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// ...
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}
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```
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## Examples
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### Sharing components with App Router
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`useParams` from `next/navigation` works in both the Pages Router and App Router. This allows you to create shared components that work in either context:
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```tsx filename="components/breadcrumb.tsx" switcher
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import { useParams } from 'next/navigation'
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// This component works in both pages/ and app/
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export function Breadcrumb() {
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const params = useParams<{ slug: string }>()
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if (!params) {
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// Fallback for Pages Router during prerendering
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return <nav>Home / ...</nav>
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}
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return <nav>Home / {params.slug}</nav>
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}
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```
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```jsx filename="components/breadcrumb.js" switcher
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import { useParams } from 'next/navigation'
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// This component works in both pages/ and app/
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export function Breadcrumb() {
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const params = useParams()
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if (!params) {
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// Fallback for Pages Router during prerendering
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return <nav>Home / ...</nav>
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}
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return <nav>Home / {params.slug}</nav>
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}
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```
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> **Good to know**: When using this component in the App Router, `useParams` never returns `null`, so the fallback branch will not be rendered.
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## Version History
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| Version | Changes |
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| --------- | ----------------------- |
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| `v13.3.0` | `useParams` introduced. |
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