Authorization

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

Before you can access request headers in any context or middleware, you need to set the outgoing request headers. See here.

Create context from request headers

server/trpc/context.ts
import { inferAsyncReturnType } from '@trpc/server'
import { decodeAndVerifyJwtToken } from './somewhere/in/your/app/utils'

export async function createContext(event: H3Event) {
  // 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
  const authorization = getRequestHeader(event, 'authorization')
  async function getUserFromHeader() {
    if (authorization) {
      const user = await decodeAndVerifyJwtToken(authorization.split(' ')[1])
      return user
    }
    return null
  }
  const user = await getUserFromHeader()

  return {
    user,
  }
}
type Context = inferAsyncReturnType<typeof createContext>

Option 1: Authorize using resolver

import { TRPCError, initTRPC } 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(({ input, ctx }) => `hello ${input ?? ctx.user?.name ?? 'world'}`),
  // checked in resolver
  secret: t.procedure.query(({ ctx }) => {
    if (!ctx.user) {
      throw new TRPCError({ code: 'UNAUTHORIZED' })
    }
    return {
      secret: 'sauce',
    }
  }),
})

Option 2: Authorize using middleware

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

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

const isAuthed = t.middleware(({ next, ctx }) => {
  if (!ctx.user?.isAdmin) {
    throw new TRPCError({ code: 'UNAUTHORIZED' })
  }
  return next({
    ctx: {
      user: ctx.user,
    },
  })
})

// you can reuse this for any procedure
export const protectedProcedure = t.procedure.use(isAuthed)

t.router({
  // this is accessible for everyone
  hello: t.procedure
    .input(z.string().nullish())
    .query(({ input, ctx }) => `hello ${input ?? ctx.user?.name ?? 'world'}`),
  admin: t.router({
    // this is accessible only to admins
    secret: protectedProcedure.query(({ ctx }) => {
      return {
        secret: 'sauce',
      }
    }),
  }),
})

This page is entirely based on authorization docs of tRPC with a minimal change made to work with Nuxt.

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