Nuxt/docs/3.api/1.composables/use-fetch.md

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# `useFetch`
This composable provides a convenient wrapper around [`useAsyncData`](/docs/api/composables/use-async-data) and [`$fetch`](/docs/api/utils/dollarfetch).
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.
## Type
```ts [Signature]
function useFetch(
url: string | Request | Ref<string | Request> | () => string | Request,
options?: UseFetchOptions<DataT>
): Promise<AsyncData<DataT>>
type UseFetchOptions = {
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
default?: () => DataT
transform?: (input: DataT) => DataT
pick?: string[]
watch?: WatchSource[]
}
type AsyncData<DataT> = {
data: Ref<DataT>
pending: Ref<boolean>
refresh: (opts?: { dedupe?: boolean }) => Promise<void>
execute: () => Promise<void>
error: Ref<Error | boolean>
}
```
## Params
* **URL**: The URL to fetch.
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* **Options (extends [unjs/ofetch](https://github.com/unjs/ofetch) options & [AsyncDataOptions](/docs/api/composables/use-async-data#params))**:
* `method`: Request method.
* `query`: Adds query search params to URL using [ufo](https://github.com/unjs/ufo)
* `params`: Alias for `query`
* `body`: Request body - automatically stringified (if an object is passed).
* `headers`: Request headers.
* `baseURL`: Base URL for the request.
::alert{type=info}
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`)**:
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* `key`: a unique key to ensure that data fetching can be properly de-duplicated across requests, if not provided, it will be generated based on the static code location where `useAsyncData` is used.
* `server`: Whether to fetch the data on the server (defaults to `true`).
* `default`: A factory function to set the default value of the data, before the async function resolves - particularly useful with the `lazy: true` option.
* `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`.
* `transform`: A function that can be used to alter `handler` function result after resolving.
* `immediate`: When set to `false`, will prevent the request from firing immediately. (defaults to `true`)
::alert{type=warning}
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`.
::
## 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.
By default, Nuxt waits until a `refresh` is finished before it can be executed again.
::alert{type=warning}
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>`.
::
## Example
```ts
const { data, pending, error, refresh } = await useFetch('https://api.nuxtjs.dev/mountains',{
pick: ['title']
})
```
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Adding Query Search Params:
Using the `query` option, you can add search parameters to your query. This option is extended from [unjs/ofetch](https://github.com/unjs/ofetch) and is using [unjs/ufo](https://github.com/unjs/ufo) to create the URL. Objects are automatically stringified.
```ts
const param1 = ref('value1')
const { data, pending, error, refresh } = await useFetch('https://api.nuxtjs.dev/mountains',{
query: { param1, param2: 'value2' }
})
```
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Results in `https://api.nuxtjs.dev/mountains?param1=value1&param2=value2`
Using [interceptors](https://github.com/unjs/ofetch#%EF%B8%8F-interceptors):
```ts
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
return response._data
},
onResponseError({ request, response, options }) {
// Handle the response errors
}
})
```
::alert{type=warning}
`useFetch` is a reserved function name transformed by the compiler, so you should not name your own function `useFetch`.
::
:ReadMore{link="/docs/getting-started/data-fetching"}
::LinkExample{link="/docs/examples/composables/use-fetch"}
::