Nuxt/docs/2.guide/4.recipes/3.custom-usefetch.md
2024-08-13 16:39:40 +01:00

110 lines
3.7 KiB
Markdown

---
navigation.title: 'Custom useFetch'
title: Custom useFetch in Nuxt
description: How to create a custom fetcher for calling your external API in Nuxt 3.
---
When working with Nuxt, you might be making the frontend and fetching an external API, and you might want to set some default options for fetching from your API.
The [`$fetch`](/docs/api/utils/dollarfetch) utility function (used by the [`useFetch`](/docs/api/composables/use-fetch) composable) is intentionally not globally configurable. This is important so that fetching behavior throughout your application remains consistent, and other integrations (like modules) can rely on the behavior of core utilities like `$fetch`.
However, Nuxt provides a way to create a custom fetcher for your API (or multiple fetchers if you have multiple APIs to call).
## Custom `$fetch`
Let's create a custom `$fetch` instance with a [Nuxt plugin](/docs/guide/directory-structure/plugins).
::note
`$fetch` is a configured instance of [ofetch](https://github.com/unjs/ofetch) which supports adding the base URL of your Nuxt server as well as direct function calls during SSR (avoiding HTTP roundtrips).
::
Let's pretend here that:
- The main API is https://api.nuxt.com
- We are storing the JWT token in a session with [nuxt-auth-utils](https://github.com/atinux/nuxt-auth-utils)
- If the API responds with a `401` status code, we redirect the user to the `/login` page
```ts [plugins/api.ts]
export default defineNuxtPlugin((nuxtApp) => {
const { session } = useUserSession()
const api = $fetch.create({
baseURL: 'https://api.nuxt.com',
onRequest({ request, options, error }) {
if (session.value?.token) {
const headers = options.headers ||= {}
if (Array.isArray(headers)) {
headers.push(['Authorization', `Bearer ${session.value?.token}`])
} else if (headers instanceof Headers) {
headers.set('Authorization', `Bearer ${session.value?.token}`)
} else {
headers.Authorization = `Bearer ${session.value?.token}`
}
}
},
async onResponseError({ response }) {
if (response.status === 401) {
await nuxtApp.runWithContext(() => navigateTo('/login'))
}
}
})
// Expose to useNuxtApp().$api
return {
provide: {
api
}
}
})
```
With this Nuxt plugin, `$api` is exposed from `useNuxtApp()` to make API calls directly from the Vue components:
```vue [app.vue]
<script setup>
const { $api } = useNuxtApp()
const { data: modules } = await useAsyncData('modules', () => $api('/modules'))
</script>
```
::callout
Wrapping with [`useAsyncData`](/docs/api/composables/use-async-data) **avoid double data fetching when doing server-side rendering** (server & client on hydration).
::
## Custom `useFetch`/`useAsyncData`
Now that `$api` has the logic we want, let's create a `useAPI` composable to replace the usage of `useAsyncData` + `$api`:
```ts [composables/useAPI.ts]
import type { UseFetchOptions } from 'nuxt/app'
export function useAPI<T>(
url: string | (() => string),
options?: UseFetchOptions<T>,
) {
return useFetch(url, {
...options,
$fetch: useNuxtApp().$api
})
}
```
Let's use the new composable and have a nice and clean component:
```vue [app.vue]
<script setup>
const { data: modules } = await useAPI('/modules')
</script>
```
::note
This example demonstrates how to use a custom `useFetch`, but the same structure is identical for a custom `useAsyncData`.
::
::callout{icon="i-simple-icons-youtube" color="red" to="https://www.youtube.com/watch?v=jXH8Tr-exhI"}
Watch a video about custom `$fetch` and Repository Pattern in Nuxt.
::
::note
We are currently discussing to find a cleaner way to let you create a custom fetcher, see https://github.com/nuxt/nuxt/issues/14736.
::