---
title: 'usePathParams'
description: 'A hook to validate request path parameters'
group: 'Hooks'
---

An Exobase hook that validates path parameters in the request.

Install

``sh
yarn add @exobase/use-path-params


or


yarn add @exobase/hooks
`

Import

`ts
import { usePathParams } from '@exobase/use-path-params'
// or
import { usePathParams } from '@exobase/hooks'
`

Usage

`ts
import { compose } from 'radash'
import type { Props } from '@exobase/core'
import { useNext } from '@exobase/use-next'
import { usePathParams } from '@exobase/use-path-params'

export const findBookById = async (props: Props) => {
return db.books.find(props.args.bookId)
}

export default compose(
useNext(),
usePathParams(z => ({
libraryId: z.string(),
bookId: z.string().tranform(id => parseInt(id)),
}))
findBookById
)
`

when called with

`sh
curl /api/libraries/ny-public-library/books/3328
`

In some cases, you may need to parse the path params first. Sometimes the framework + root hook will do the param parsing. In other cases the useRouter hook, if you use it, will do the param parsing. If you're using AWS Lambda (without a router) there is no built in path param utility so you'll need to parse the path params manually using usePathParamsParser.

`ts
import { compose } from 'radash'
import type { Props } from '@exobase/core'
import { useLambda } from '@exobase/use-lambda'
import { usePathParamsParser } from '@exobase/use-path-params-parser'
import { usePathParams } from '@exobase/use-path-params'

export const findBookById = async (props: Props) => {
return db.books.find(props.args.bookId)
}

export default compose(
useLambda(),
usePathParamsParser('/libraries/{libraryId}/books/{bookId}'),
usePathParams(z => ({
libraryId: z.string(),
bookId: z.string().tranform(id => parseInt(id)),
}))
findBookById
)
``