tRPC Bun Adapter

Description

trpc-bun-adapter is a tRPC adapter for Bun.

Start both HTTP and WebSockets transports with ease.

Quick Start

Install packages:

bun install @trpc/server trpc-bun-adapter

Create a server.ts file with the following content:

import {initTRPC} from '@trpc/server';
import {createBunServeHandler} from 'trpc-bun-adapter';

const t = initTRPC.create();

export const router = t.router({
    ping: t.procedure.query(() => "pong"),
});

Bun.serve(createBunServeHandler({ router }));

To start the server, run:

bun run server.ts
bun run --watch server.ts # to restart on file changes

Check that it works:

curl http://localhost:3000/ping

Example

for a full example, see the example directory.

API Reference

Ensure you have created a router.ts file as outlined in the tRPC documentation: Define Routers.

createBunServeHandler

Creates a Bun serve handler:

import {createBunServeHandler, CreateBunContextOptions} from 'trpc-bun-adapter';
import {router} from './router';

const createContext = (opts: CreateBunContextOptions) => ({
    user: 1,
});

Bun.serve(
    createBunServeHandler(
        {
            router,
            // optional arguments:
            endpoint: '/trpc', // Default to ""
            createContext,
            onError: console.error,
            responseMeta(opts) {
                return {
                    status: 202,
                    headers: {},
                }
            },
            batching: {
                enabled: true,
            },
        },
        {
            // Bun serve options
            port: 3001,
            fetch(request, server) {
                // will be executed if it's not a TRPC request
                return new Response("Hello world");
            },
        },
    ),
);

To add response headers like Cross-origin resource sharing (CORS) use responseMeta option:

Bun.serve(
   createBunServeHandler({
         router: appRouter,
         responseMeta(opts) {
            return {
               status: 200,
               headers: {
                  "Access-Control-Allow-Origin": "*",
                  "Access-Control-Allow-Methods": "GET, POST, OPTIONS",
                  "Access-Control-Allow-Headers": "Content-Type, Authorization"
               }
            };
         }
      }
   )
);

createBunHttpHandler

Creates a Bun HTTP handler for tRPC HTTP requests:

import {createBunHttpHandler, CreateBunContextOptions} from 'trpc-bun-adapter';
import {router} from './router';

const createContext = (opts: CreateBunContextOptions) => ({
    user: 1,
});

const bunHandler = createBunHttpHandler({
    router,
    // optional arguments:
    endpoint: '/trpc', // Default to ""
    createContext,
    onError: console.error,
    responseMeta(opts) {
        return {
            status: 202,
            headers: {},
        }
    },
    batching: {
        enabled: true,
    },
    emitWsUpgrades: false, // pass true to upgrade to WebSocket
});

Bun.serve({
    fetch(request, response) {
        return bunHandler(request, response) ?? new Response("Not found", {status: 404});
    }
});

createBunWsHandler

Creates a Bun WebSocket handler for tRPC websocket requests:

import { createBunWSHandler, CreateBunContextOptions } from './src';
import { router } from './router';

const createContext = (opts: CreateBunContextOptions) => ({
    user: 1,
});

const websocket = createBunWSHandler({
    router,
    // optional arguments:
    createContext,
    onError: console.error,
    batching: {
        enabled: true,
    },
});

Bun.serve({
    fetch(request, server) {
        const data = {
            req: request // This is required for the adapter to work properly.
        };
        if (server.upgrade(request, { data })) {
            return;
        }

        return new Response("Please use websocket protocol", {status: 404});
    },
    websocket,
});

Note that it is required to store the request object on the socket data context in order for this adapter to work.

CreateBunContextOptions

To ensure your router recognizes the context type, define a createContext function utilizing the CreateBunContextOptions type:

import { initTRPC } from '@trpc/server';
import type { CreateBunContextOptions } from "src/createBunHttpHandler";

export const createContext = async (opts: CreateBunContextOptions) => {
    return {
        authorization: req.headers.get('Authorization')
    };
};

With createContext defined, you can use it in your router to access the context, such as the authorization information:

const t = initTRPC.context<typeof createContext>().create();

export const router = t.router({
    session: t.procedure.query(({ ctx }) => ctx.authorization),
});

Finally, pass your createContext function besides router to createBunHttpHandler. This integrates your custom context into the HTTP handler setup:

createBunHttpHandler({
    router,
    createContext,
})

Read more documentation about tRPC contexts here: Contexts

License

This project is licensed under the MIT License - see the LICENSE file for details.

Contributing

Contributions are welcome! Feel free to open issues and pull requests.