Next.js Adapter

tip

tRPC's support for Next.js is far more expansive than just an adapter. This page covers a brief summary of how to set up the adapter, but complete documentation is available here

Example app

Description	Links
Next.js Minimal Starter	CodeSandbox Source

Next.js example

Serving your tRPC router in a Next.js project is straight-forward. Just create an API handler in pages/api/trpc/[trpc].ts as shown below:

pages/api/trpc/[trpc].ts
ts
import { createNextApiHandler } from '@trpc/server/adapters/next';
import { createContext } from '../../../server/trpc/context';
import { appRouter } from '../../../server/trpc/router/_app';
// @link https://nextjs.org/docs/api-routes/introduction
export default createNextApiHandler({
  router: appRouter,
  createContext,
});

pages/api/trpc/[trpc].ts
ts
import { createNextApiHandler } from '@trpc/server/adapters/next';
import { createContext } from '../../../server/trpc/context';
import { appRouter } from '../../../server/trpc/router/_app';
// @link https://nextjs.org/docs/api-routes/introduction
export default createNextApiHandler({
  router: appRouter,
  createContext,
});

Handling CORS, and other Advanced usage

While you can usually just "set and forget" the API Handler as shown above, sometimes you might want to modify it further.

The API handler created by createNextApiHandler and equivalents in other frameworks is just a function that takes req and res objects. This means you can also modify those objects before passing them to the handler, for example to enable CORS.

pages/api/trpc/[trpc].ts
ts
import { createNextApiHandler } from '@trpc/server/adapters/next';
import { createContext } from '../../../server/trpc/context';
import { appRouter } from '../../../server/trpc/router/_app';
// create the API handler, but don't return it yet
const nextApiHandler = createNextApiHandler({
  router: appRouter,
  createContext,
});
// @link https://nextjs.org/docs/api-routes/introduction
export default async function handler(
  req: NextApiRequest,
  res: NextApiResponse,
) {
  // We can use the response object to enable CORS
  res.setHeader('Access-Control-Allow-Origin', '*');
  res.setHeader('Access-Control-Request-Method', '*');
  res.setHeader('Access-Control-Allow-Methods', 'OPTIONS, GET');
  res.setHeader('Access-Control-Allow-Headers', '*');
  // If you need to make authenticated CORS calls then
  // remove what is above and uncomment the below code
  // Allow-Origin has to be set to the requesting domain that you want to send the credentials back to
  // res.setHeader('Access-Control-Allow-Origin', 'http://example:6006');
  // res.setHeader('Access-Control-Request-Method', '*');
  // res.setHeader('Access-Control-Allow-Methods', 'OPTIONS, GET');
  // res.setHeader('Access-Control-Allow-Headers', 'content-type');
  // res.setHeader('Referrer-Policy', 'no-referrer');
  // res.setHeader('Access-Control-Allow-Credentials', 'true');
  if (req.method === 'OPTIONS') {
    res.writeHead(200);
    return res.end();
  }
  // finally pass the request on to the tRPC handler
  return nextApiHandler(req, res);
}

pages/api/trpc/[trpc].ts
ts
import { createNextApiHandler } from '@trpc/server/adapters/next';
import { createContext } from '../../../server/trpc/context';
import { appRouter } from '../../../server/trpc/router/_app';
// create the API handler, but don't return it yet
const nextApiHandler = createNextApiHandler({
  router: appRouter,
  createContext,
});
// @link https://nextjs.org/docs/api-routes/introduction
export default async function handler(
  req: NextApiRequest,
  res: NextApiResponse,
) {
  // We can use the response object to enable CORS
  res.setHeader('Access-Control-Allow-Origin', '*');
  res.setHeader('Access-Control-Request-Method', '*');
  res.setHeader('Access-Control-Allow-Methods', 'OPTIONS, GET');
  res.setHeader('Access-Control-Allow-Headers', '*');
  // If you need to make authenticated CORS calls then
  // remove what is above and uncomment the below code
  // Allow-Origin has to be set to the requesting domain that you want to send the credentials back to
  // res.setHeader('Access-Control-Allow-Origin', 'http://example:6006');
  // res.setHeader('Access-Control-Request-Method', '*');
  // res.setHeader('Access-Control-Allow-Methods', 'OPTIONS, GET');
  // res.setHeader('Access-Control-Allow-Headers', 'content-type');
  // res.setHeader('Referrer-Policy', 'no-referrer');
  // res.setHeader('Access-Control-Allow-Credentials', 'true');
  if (req.method === 'OPTIONS') {
    res.writeHead(200);
    return res.end();
  }
  // finally pass the request on to the tRPC handler
  return nextApiHandler(req, res);
}

Route Handlers

If you're trying out the Next.js App Router and want to use route handlers, you can do so by using the fetch adapter, as they build on web standard Request and Response objects:

app/api/trpc/[trpc]/route.ts
ts
import { fetchRequestHandler } from '@trpc/server/adapters/fetch';
import { appRouter } from '~/server/api/router';
function handler(req: Request) {
  return fetchRequestHandler({
    endpoint: '/api/trpc',
    req,
    router: appRouter,
    createContext: () => ({ ... })
  });
}
export { handler as GET, handler as POST };

app/api/trpc/[trpc]/route.ts
ts
import { fetchRequestHandler } from '@trpc/server/adapters/fetch';
import { appRouter } from '~/server/api/router';
function handler(req: Request) {
  return fetchRequestHandler({
    endpoint: '/api/trpc',
    req,
    router: appRouter,
    createContext: () => ({ ... })
  });
}
export { handler as GET, handler as POST };