Nuxt/docs/3.api/2.composables/use-fetch.md

title	description	links
useFetch	Fetch data from an API endpoint with a SSR-friendly composable.	label icon to size Source i-simple-icons-github https://github.com/nuxt/nuxt/blob/main/packages/nuxt/src/app/composables/fetch.ts xs

This composable provides a convenient wrapper around useAsyncData and $fetch. It automatically generates a key based on URL and fetch options, provides type hints for request url based on server routes, and infers API response type.

::callout useFetch is a composable meant to be called directly in a setup function, plugin, or route middleware. It returns reactive composables and handles adding responses to the Nuxt payload so they can be passed from server to client without re-fetching the data on client side when the page hydrates. ::

Usage

<script setup>
const route = useRoute()

const { data, pending, error, refresh } = await useFetch(`https://api.nuxtjs.dev/mountains/${route.params.slug}`, {
  pick: ['title']
})
</script>

::callout data, pending, status and error are Vue refs and they should be accessed with .value when used within the <script setup>, while refresh/execute is a plain function for refetching data. ::

Using the query option, you can add search parameters to your query. This option is extended from unjs/ofetch and is using unjs/ufo to create the URL. Objects are automatically stringified.

const param1 = ref('value1')
const { data, pending, error, refresh } = await useFetch('https://api.nuxtjs.dev/mountains', {
  query: { param1, param2: 'value2' }
})

The above example results in https://api.nuxtjs.dev/mountains?param1=value1&param2=value2.

You can also use interceptors:

const { data, pending, error, refresh } = await useFetch('/api/auth/login', {
  onRequest({ request, options }) {
    // Set the request headers
    options.headers = options.headers || {}
    options.headers.authorization = '...'
  },
  onRequestError({ request, options, error }) {
    // Handle the request errors
  },
  onResponse({ request, response, options }) {
    // Process the response data
    localStorage.setItem('token', response._data.token)
  },
  onResponseError({ request, response, options }) {
    // Handle the response errors
  }
})

::callout{color="amber" icon="i-ph-warning-duotone"} useFetch is a reserved function name transformed by the compiler, so you should not name your own function useFetch. ::

:link-example{to="/docs/examples/advanced/use-custom-fetch-composable"}

:read-more{to="/docs/getting-started/data-fetching"}

:link-example{to="/docs/examples/features/data-fetching"}

Params

• URL: The URL to fetch.
• Options (extends unjs/ofetch options & AsyncDataOptions):
  • method: Request method.
  • query: Adds query search params to URL using ufo
  • params: Alias for query
  • body: Request body - automatically stringified (if an object is passed).
  • headers: Request headers.
  • baseURL: Base URL for the request.
  • timeout: Milliseconds to automatically abort request

::callout All fetch options can be given a computed or ref value. These will be watched and new requests made automatically with any new values if they are updated. ::

• Options (from useAsyncData):
  • key: a unique key to ensure that data fetching can be properly de-duplicated across requests, if not provided, it will be automatically generated based on URL and fetch options
  • server: whether to fetch the data on the server (defaults to true)
  • lazy: whether to resolve the async function after loading the route, instead of blocking client-side navigation (defaults to false)
  • immediate: when set to false, will prevent the request from firing immediately. (defaults to true)
  • default: a factory function to set the default value of the data, before the async function resolves - useful with the lazy: true or immediate: false option
  • transform: a function that can be used to alter handler function result after resolving
  • getCachedData: Provide a function which returns cached data. A null or undefined return value will trigger a fetch. By default, this is: key => nuxt.isHydrating ? nuxt.payload.data[key] : nuxt.static.data[key], which only caches data when payloadExtraction is enabled.
  • pick: only pick specified keys in this array from the handler function result
  • watch: watch an array of reactive sources and auto-refresh the fetch result when they change. Fetch options and URL are watched by default. You can completely ignore reactive sources by using watch: false. Together with immediate: false, this allows for a fully-manual useFetch.
  • deep: return data in a deep ref object (it is true by default). It can be set to false to return data in a shallow ref object, which can improve performance if your data does not need to be deeply reactive.
  • dedupe: avoid fetching same key more than once at a time (defaults to cancel). Possible options:
    • cancel - cancels existing requests when a new one is made
    • defer - does not make new requests at all if there is a pending request

::callout If you provide a function or ref as the url parameter, or if you provide functions as arguments to the options parameter, then the useFetch call will not match other useFetch calls elsewhere in your codebase, even if the options seem to be identical. If you wish to force a match, you may provide your own key in options. ::

::callout{icon="i-simple-icons-youtube" color="gray" to="https://www.youtube.com/watch?v=aQPR0xn-MMk" target="_blank"} Learn how to use transform and getCachedData to avoid superfluous calls to an API and cache data for visitors on the client. ::

Return Values

• data: the result of the asynchronous function that is passed in.
• pending: a boolean indicating whether the data is still being fetched.
• refresh/execute: a function that can be used to refresh the data returned by the handler function.
• error: an error object if the data fetching failed.
• status: a string indicating the status of the data request ("idle", "pending", "success", "error").

By default, Nuxt waits until a refresh is finished before it can be executed again.

::callout If you have not fetched data on the server (for example, with server: false), then the data will not be fetched until hydration completes. This means even if you await useFetch on client-side, data will remain null within <script setup>. ::

Type

function useFetch<DataT, ErrorT>(
  url: string | Request | Ref<string | Request> | () => string | Request,
  options?: UseFetchOptions<DataT>
): Promise<AsyncData<DataT, ErrorT>>

type UseFetchOptions<DataT> = {
  key?: string
  method?: string
  query?: SearchParams
  params?: SearchParams
  body?: RequestInit['body'] | Record<string, any>
  headers?: Record<string, string> | [key: string, value: string][] | Headers
  baseURL?: string
  server?: boolean
  lazy?: boolean
  immediate?: boolean
  getCachedData?: (key: string) => DataT
  deep?: boolean
  dedupe?: 'cancel' | 'defer'
  default?: () => DataT
  transform?: (input: DataT) => DataT
  pick?: string[]
  watch?: WatchSource[] | false
}

type AsyncData<DataT, ErrorT> = {
  data: Ref<DataT | null>
  pending: Ref<boolean>
  refresh: (opts?: AsyncDataExecuteOptions) => Promise<void>
  execute: (opts?: AsyncDataExecuteOptions) => Promise<void>
  error: Ref<ErrorT | null>
  status: Ref<AsyncDataRequestStatus>
}

interface AsyncDataExecuteOptions {
  dedupe?: 'cancel' | 'defer'
}

type AsyncDataRequestStatus = 'idle' | 'pending' | 'success' | 'error'