Fastify Adapter

Use oRPC with Fastify servers via RPCHandler or OpenAPIHandler, with content type parser tips and event stream options.

Server Usage

import { onError } from '@orpc/server'
import { RPCHandler } from '@orpc/server/fastify'
import { CORSHandlerPlugin } from '@orpc/server/plugins'
import Fastify from 'fastify'

const handler = new RPCHandler(router, {
  plugins: [new CORSHandlerPlugin()],
  interceptors: [
    onError((error) => {
      console.error(error)
    }),
  ],
})

const app = Fastify()

app.all('/rpc/*', async (req, reply) => {
  const { matched } = await handler.handle(req, reply, {
    prefix: '/rpc',
    context: {}, // Provide initial context if needed, can be an async function
  })

  if (matched) {
    return reply
  }

  return reply.status(404).send('Not found')
})

app.listen({ port: 3000 }).then(() => console.log('Listening on port 3000'))

import { OpenAPIHandler } from '@orpc/openapi/fastify'
import { onError } from '@orpc/server'
import { CORSHandlerPlugin } from '@orpc/server/plugins'
import Fastify from 'fastify'

const handler = new OpenAPIHandler(router, {
  plugins: [new CORSHandlerPlugin()],
  interceptors: [
    onError((error) => {
      console.error(error)
    }),
  ],
})

const app = Fastify()

app.all('/api/*', async (req, reply) => {
  const { matched } = await handler.handle(req, reply, {
    prefix: '/api',
    context: {}, // Provide initial context if needed, can be an async function
  })

  if (matched) {
    return reply
  }

  return reply.status(404).send('Not found')
})

app.listen({ port: 3000 }).then(() => console.log('Listening on port 3000'))

Fastify only accepts content types it has a registered parser for, and parses request bodies itself. Registering a catch-all parser lets oRPC handle every content type, but bodies it receives skip Fastify’s bodyLimit, so cap them with Request Limit or Tmp File Upload:

// Optional, let oRPC parse all content types
app.removeAllContentTypeParsers()

// Optional, support all content types
app.addContentTypeParser('*', (request, payload, done) => {
  done(null, undefined)
})

To better support Blob, File, and ReadableStream<Uint8Array> at the root level in cross-origin scenarios, extend your CORS allowlist to allow clients to read the Content-Disposition and Standard-Server response headers. Learn more in the Standard Server documentation. If you use the CORS Plugin, include them in exposeHeaders:

const cors = new CORSHandlerPlugin({
  exposeHeaders: ['Content-Disposition', 'Standard-Server'],
})

Event Stream Options

You can configure how an AsyncIteratorObject is streamed to the client using the sendStandardResponse.eventStream options when creating the handler.

const handler = new OpenAPIHandler(router, {
  sendStandardResponse: {
    eventStream: {
      /**
       * Initial comment sent immediately upon stream start to flush headers. This allows the
       * receiving side to establish the connection without waiting for the first event.
       *
       * `false` disables it, an object customizes it.
       *
       * @default true
       */
      initialComment: {
        /**
         * The content of the initial comment sent upon stream start. Must not include newline characters.
         *
         * @default ''
         */
        comment: '',
      },
      /**
       * Ping comment sent periodically to keep the connection alive.
       *
       * `false` disables it, an object customizes it.
       *
       * @default true
       */
      keepAlive: {
        /**
         * Interval (in milliseconds) between ping comments sent after the last event.
         *
         * @default 15000
         */
        interval: 15000,
        /**
         * The content of the ping comment. Must not include newline characters.
         *
         * @default ''
         */
        comment: '',
      },
    },
  },
})