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.

Create context from request headers

import * as trpc from '@trpc/server';
import { inferAsyncReturnType } from '@trpc/server';
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'd 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,
  };
}
type Context = inferAsyncReturnType<typeof createContext>;


// [..] Define API handler and app router

Option 1: Authorize using resolver

import * as trpc from '@trpc/server';
import { TRPCError } from '@trpc/server';
import { createRouter } from './[trpc]';

export const appRouter = createRouter()
  // open for anyone
  .query('hello', {
    input: z.string().nullish(),
    resolve: ({ input, ctx }) => {
      return `hello ${input ?? ctx.user?.name ?? 'world'}`;
    },
  })
  // checked in resolver
  .query('secret', {
    resolve: ({ ctx }) => {
      if (!ctx.user) {
        throw new TRPCError({ code: 'UNAUTHORIZED' });
      }
      return {
        secret: 'sauce',
      };
    },
  });

Option 2: Authorize using middleware

import * as trpc from '@trpc/server';
import { TRPCError } from '@trpc/server';
import { createRouter } from './[trpc]';

export const appRouter = createRouter()
  // this is accessible for everyone
  .query('hello', {
    input: z.string().nullish(),
    resolve: ({ input, ctx }) => {
      return `hello ${input ?? ctx.user?.name ?? 'world'}`;
    },
  })
  .merge(
    'admin.',
    createRouter()
      // this protects all procedures defined next in this router
      .middleware(async ({ ctx, next }) => {
        if (!ctx.user?.isAdmin) {
          throw new TRPCError({ code: 'UNAUTHORIZED' });
        }
        return next()
      })
      .query('secret', {
        resolve: ({ ctx }) => {
          return {
            secret: 'sauce',
          }
        },
    }),
  );

This middleware can be re-used for multiple sub-routers by creating a protected router helper.