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Usage with Express.js

Example app#

DescriptionURLLinks
Express server & procedure calls with node.js.n/a

How to add tRPC to existing Express.js project#

1. Install deps#

yarn add @trpc/server zod

Zod isn't a required dependency, but it's used in the sample router below.

2. Create a tRPC router#

Implement your tRPC router. A sample router is given below:

import * as trpc from '@trpc/server';import { z } from 'zod';
const appRouter = trpc  .router()  .query('getUser', {    input: z.string(),    async resolve(req) {      req.input; // string      return { id: req.input, name: 'Bilbo' };    },  })  .mutation('createUser', {    // validate input with Zod    input: z.object({ name: z.string().min(5) }),    async resolve(req) {      // use your ORM of choice      return await UserModel.create({        data: req.input,      });    },  });
// export type definition of APIexport type AppRouter = typeof appRouter;

If your router file starts getting too big, split your router into several subrouters each implemented in its own file. Then merge them into a single root appRouter.

3. Use the Express.js adapter#

tRPC includes an adapter for Express.js out of the box. This adapter lets you convert your tRPC router into an Express.js middleware.

import * as trpcExpress from '@trpc/server/adapters/express';
const appRouter = /* ... */;
const app = express();
// created for each requestconst createContext = ({  req,  res,}: trpcExpress.CreateExpressContextOptions) => ({}) // no contexttype Context = trpc.inferAsyncReturnType<typeof createContext>;
app.use(  '/trpc',  trpcExpress.createExpressMiddleware({    router: appRouter,    createContext: () => null, // no context  }));
app.listen(4000);

Your endpoints are now available via HTTP!

EndpointHTTP URI
getUserGET http://localhost:4000/trpc/getUser?input=INPUT

where INPUT is a URI-encoded JSON string.
createUserPOST http://localhost:4000/trpc/createUser

with req.body of type {name: string}