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Usage with Express.js

Example app#

DescriptionURLLinks
Next.js starter with Prisma, E2E testing, & ESLint

Quick start with create-next-appnpx create-next-app --example https://github.com/trpc/trpc --example-path examples/next-prisma-starter trpc-prisma-starter
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Express server & procedure calls with node.js.
Uses experimental subscriptions.
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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 * as trpcNext from '@trpc/server/adapters/next';
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 API
export 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 request
const createContext = ({
req,
res,
}: trpcExpress.CreateExpressContextOptions) => ({}) // no context
type 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}