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Version: 10.x

Usage with Express

Example app

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

How to add tRPC to existing Express project

1. Install deps

bash
yarn add @trpc/server@next zod
bash
yarn add @trpc/server@next 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:

server.ts
ts
import { initTRPC } from '@trpc/server';
import { z } from 'zod';
export const t = initTRPC.create();
export const appRouter = t.router({
getUser: t.procedure.input(z.string()).query((req) => {
req.input; // string
return { id: req.input, name: 'Bilbo' };
}),
createUser: t.procedure
.input(z.object({ name: z.string().min(5) }))
.mutation(async (req) => {
// use your ORM of choice
return await UserModel.create({
data: req.input,
});
}),
});
// export type definition of API
export type AppRouter = typeof appRouter;
server.ts
ts
import { initTRPC } from '@trpc/server';
import { z } from 'zod';
export const t = initTRPC.create();
export const appRouter = t.router({
getUser: t.procedure.input(z.string()).query((req) => {
req.input; // string
return { id: req.input, name: 'Bilbo' };
}),
createUser: t.procedure
.input(z.object({ name: z.string().min(5) }))
.mutation(async (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 adapter

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

server.ts
ts
import { inferAsyncReturnType, initTRPC } from '@trpc/server';
import * as trpcExpress from '@trpc/server/adapters/express';
// created for each request
const createContext = ({
req,
res,
}: trpcExpress.CreateExpressContextOptions) => ({}); // no context
type Context = inferAsyncReturnType<typeof createContext>;
const t = initTRPC.context<Context>().create();
const appRouter = t.router({
// [...]
});
const app = express();
app.use(
'/trpc',
trpcExpress.createExpressMiddleware({
router: appRouter,
createContext,
}),
);
app.listen(4000);
server.ts
ts
import { inferAsyncReturnType, initTRPC } from '@trpc/server';
import * as trpcExpress from '@trpc/server/adapters/express';
// created for each request
const createContext = ({
req,
res,
}: trpcExpress.CreateExpressContextOptions) => ({}); // no context
type Context = inferAsyncReturnType<typeof createContext>;
const t = initTRPC.context<Context>().create();
const appRouter = t.router({
// [...]
});
const app = express();
app.use(
'/trpc',
trpcExpress.createExpressMiddleware({
router: appRouter,
createContext,
}),
);
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}