Integration with Expo

Starting from Expo SDK 50, and App Router v3, Expo allows us to create API route directly in an Expo app.

1. Create app/[...slugs]+api.ts
2. Define an Elysia server
3. Export Elysia.fetch name of HTTP methods you want to use

app/[...slugs]+api.ts

import { Elysia, t } from 'elysia'

const app = new Elysia()
    .get('/', 'hello Expo')
    .post('/', ({ body }) => body, {
        body: t.Object({
            name: t.String()
        })
    })

export const GET = app.fetch 
export const POST = app.fetch 

You can treat the Elysia server as if normal Expo API route.

Prefix

If you place an Elysia server not in the root directory of the app router, you need to annotate the prefix to the Elysia server.

For example, if you place Elysia server in app/api/[...slugs]+api.ts, you need to annotate prefix as /api to Elysia server.

app/api/[...slugs]+api.ts

import { Elysia, t } from 'elysia'

const app = new Elysia({ prefix: '/api' }) 
    .get('/', 'Hello Expo')
    .post('/', ({ body }) => body, {
        body: t.Object({
            name: t.String()
        })
    })

export const GET = app.fetch
export const POST = app.fetch

This will ensure that Elysia routing will work properly in any location you place it in.

Eden

We can add Eden for end-to-end type safety similar to tRPC.

1. Export type from the Elysia server

app/[...slugs]+api.ts

import { Elysia } from 'elysia'

const app = new Elysia()
	.get('/', 'Hello Nextjs')
	.post(
		'/user',
		({ body }) => body,
		{
			body: treaty.schema('User', {
				name: 'string'
			})
		}
	)

export type app = typeof app 

export const GET = app.fetch
export const POST = app.fetch

2. Create a Treaty client

lib/eden.ts

import { treaty } from '@elysiajs/eden'
import type { app } from '../app/[...slugs]+api'

export const api = treaty<app>('localhost:3000/api')

3. Use the client in both server and client components

app/page.tsx

import { api } from '../lib/eden'

export default async function Page() {
	const message = await api.get()

	return <h1>Hello, {message}</h1>
}

Deployment

You can either directly use API route using Elysia and deploy as normal Elysia app normally if need or using experimental Expo server runtime.

If you are using Expo server runtime, you may use expo export command to create optimized build for your expo app, this will include an Expo function which is using Elysia at dist/server/_expo/functions/[...slugs]+api.js

TIP

Please note that Expo Functions are treated as Edge functions instead of normal server, so running the Edge function directly will not allocate any port.

You may use the Expo function adapter provided by Expo to deploy your Edge Function.

Currently Expo support the following adapter:

• Express
• Netlify
• Vercel