Integration with Next.js

With Next.js App Router, we can run Elysia on Next.js routes.

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

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

import { Elysia, t } from 'elysia'

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

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

Elysia will work normally as expected because of WinterCG compliance.

You can treat the Elysia server as a normal Next.js API route.

With this approach, you can have co-location of both frontend and backend in a single repository and have End-to-end type safety with Eden with both client-side and server action

Prefix

Because our Elysia server is 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/user/[[...slugs]]/route.ts, you need to annotate prefix as /user to Elysia server.

app/user/[[...slugs]]/route.ts

import { Elysia, t } from 'elysia'

export default new Elysia({ prefix: '/user' }) 
	.get('/', 'Hello Nextjs')
    .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.

Eden

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

1. Export type from the Elysia server

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

import { Elysia } from 'elysia'

const app = new Elysia({ prefix: '/api' })
	.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/api/[[...slugs]]/route'

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>
}

Please refer to Next.js Route Handlers for more information.