The createContext function is called for each incoming request, so here you can add contextual information about the calling user from the request object.

server/context.ts

ts

import * as trpcNext from '@trpc/server/adapters/next';

import { decodeAndVerifyJwtToken } from './somewhere/in/your/app/utils';

export async function createContext({

req,

res,

}: trpcNext.CreateNextContextOptions) {

// Create your context based on the request object

// Will be available as `ctx` in all your resolvers

// This is just an example of something you might want to do in your ctx fn

async function getUserFromHeader() {

`if (req.headers.authorization) {`

  `const user = await decodeAndVerifyJwtToken(`

    `req.headers.authorization.split(' ')[1],`

  `);`

  `return user;`

`}`

`return null;`

}

const user = await getUserFromHeader();

return {

`user,`

};

}

export type Context = Awaited<ReturnType<typeof createContext>>;

server/routers/_app.ts

ts

import { initTRPC, TRPCError } from '@trpc/server';

import type { Context } from '../context';

export const t = initTRPC.context<Context>().create();

const appRouter = t.router({

// open for anyone

hello: t.procedure

`.input(z.string().nullish())`

``.query((opts) => `hello ${opts.input ?? opts.ctx.user?.name ?? 'world'}`),``

// checked in resolver

secret: t.procedure.query((opts) => {

`if (!opts.ctx.user) {`

  `throw new TRPCError({ code: 'UNAUTHORIZED' });`

`}`

`return {`

  `secret: 'sauce',`

`};`

}),

});

Option 2: Authorize using middleware​

server/routers/_app.ts

ts

import { initTRPC, TRPCError } from '@trpc/server';

export const t = initTRPC.context<Context>().create();

// you can reuse this for any procedure

export const protectedProcedure = t.procedure.use(

async function isAuthed(opts) {

`const { ctx } = opts;`

``// `ctx.user` is nullable``

`if (!ctx.user) {`

  `//     ^?`

  `throw new TRPCError({ code: 'UNAUTHORIZED' });`

`}`

`return opts.next({`

  `ctx: {`

    `// ✅ user value is known to be non-null now`

    `user: ctx.user,`

    `// ^?`

  `},`

`});`

},

);

t.router({

// this is accessible for everyone

hello: t.procedure

`.input(z.string().nullish())`

``.query((opts) => `hello ${opts.input ?? opts.ctx.user?.name ?? 'world'}`),``

admin: t.router({

`// this is accessible only to admins`

`secret: protectedProcedure.query((opts) => {`

  `return {`

    `secret: 'sauce',`

  `};`

`}),`

}),

});