Tom•11mo ago

Return TRPC Error from NextJS middleware

I am using trpc for my app's api but Im using NextJS middleware + upstash ratelimitting for.... well ratelimitting. Is there a way return a TRPC error from the middleware route?

26 Replies

Tom•11mo ago

Bump?

Alex / KATT 🐱•11mo ago

Throw it and use an error formatter

Tom•11mo ago

well in the nextjs middleware i can't really throw it. i could superjson the error and res.send() it. would that work?

BillyBob•6mo ago

@Tom How did you get on with this? and how were you able to run tRPC in the middleware? I am currently trying to redirect if a user is not authenticated in nextjs middleware Something like this:

import { api } from './app/trpc/server'
import { TRPCClientError } from '@trpc/client'
import { NextResponse } from 'next/server'
import type { NextRequest } from 'next/server'

// This function can be marked `async` if using `await` inside
export function middleware(request: NextRequest) {
  console.log('Haha LOL 123')
  return api.userRouter.getCurrentUser.query().catch((err) => {
    if (err instanceof TRPCClientError) {
      if (err.data.code === 'UNAUTHORIZED') {
        return NextResponse.redirect(new URL('/login', request.url))
      }
    }
  })
}

//See "Matching Paths" below to learn more
export const config = {
  matcher: '/dashboard/',
}

import { api } from './app/trpc/server'
import { TRPCClientError } from '@trpc/client'
import { NextResponse } from 'next/server'
import type { NextRequest } from 'next/server'

// This function can be marked `async` if using `await` inside
export function middleware(request: NextRequest) {
  console.log('Haha LOL 123')
  return api.userRouter.getCurrentUser.query().catch((err) => {
    if (err instanceof TRPCClientError) {
      if (err.data.code === 'UNAUTHORIZED') {
        return NextResponse.redirect(new URL('/login', request.url))
      }
    }
  })
}

//See "Matching Paths" below to learn more
export const config = {
  matcher: '/dashboard/',
}

but i keep getting the error : Invariant: headers() expects to have requestAsyncStorage, none available.

Tom•6mo ago

To be honest, I never got a great answer. So I just manually worked around it on the client side. So if I ever got a json error from my service I assume it was the middleware rejecting it

BillyBob•6mo ago

I got advised today to do a simple fetch() query to the tRPC endpoint. The code snippet above i shared did not work at all

MarvinKR•6mo ago

Why use NextJS middleware and not t.middleware?

BillyBob•6mo ago

@MarvinKR Because in my case I want to redirect the user when they become unauthenticated

MarvinKR•6mo ago

Can’t you redirect inside tRPC?

BillyBob•6mo ago

Apparently not unless I am missing something? Isn’t trpc doing fetch requests under the hood? So a redirect would not work.

Alex / KATT 🐱•6mo ago

you're correct this looks good to me

BillyBob•6mo ago

I couldn't get the above to work.

Alex / KATT 🐱•6mo ago

seems to be something with client setup

BillyBob•6mo ago

I am using App Router with NextJS 14 - Monorepo but with separated server and client This works: But i don't like that it will do an extra API call on every request.

const fetchUser = (req: NextRequest): Promise<User | null> =>
  fetch('http://localhost:4000/trpc/userRouter.getCurrentUser', {
    headers: Object.fromEntries(req.headers),
  })
    .then((response) => {
      if (!response.ok) {
        throw new Error(`HTTP error! Status: ${response.status}`)
      }
      return response.json() as Promise<ApiResponse>
    })
    .then(({ result }) => result.data.json)
    .catch((error) => {
      console.error('Error fetching user:', error)
      return null // Return null or handle the error in an appropriate way
    })

export async function middleware(request: NextRequest) {
  const user = await fetchUser(request)
  if (!user) return NextResponse.redirect(new URL('/login', request.url))
  return NextResponse.next()
}

const fetchUser = (req: NextRequest): Promise<User | null> =>
  fetch('http://localhost:4000/trpc/userRouter.getCurrentUser', {
    headers: Object.fromEntries(req.headers),
  })
    .then((response) => {
      if (!response.ok) {
        throw new Error(`HTTP error! Status: ${response.status}`)
      }
      return response.json() as Promise<ApiResponse>
    })
    .then(({ result }) => result.data.json)
    .catch((error) => {
      console.error('Error fetching user:', error)
      return null // Return null or handle the error in an appropriate way
    })

export async function middleware(request: NextRequest) {
  const user = await fetchUser(request)
  if (!user) return NextResponse.redirect(new URL('/login', request.url))
  return NextResponse.next()
}

Alex / KATT 🐱•6mo ago

can you show me your experimental_createTRPCNextAppDirServer-setup? i have an idea or like show me where const api is defined

BillyBob•6mo ago

'use server'

import { headers } from 'next/headers'
import type { TRPCLink } from '@trpc/client'
import { loggerLink, httpBatchLink, createTRPCProxyClient } from '@trpc/client'
import superjson from 'superjson'
import type { AppRouter } from '@api/server/router'
import { observable } from '@trpc/server/observable'
import { permanentRedirect } from 'next/navigation'

// export const api = experimental_createTRPCNextAppDirServer<AppRouter>({
//   config() {
//     return {
//       transformer: superjson,
//       links: [
//         loggerLink({
//           enabled: (opts) => {
//             //console.log(opts)
//             return (
//               process.env.NODE_ENV === 'development' ||
//               (opts.direction === 'down' && opts.result instanceof Error)
//             )
//           },
//         }),
//         httpBatchLink({
//           url: 'http://localhost:4000/trpc',
//           headers: Object.fromEntries(headers()),
//           fetch(url, options) {
//             return fetch(url, {
//               ...options,
//               credentials: 'include',
//             })
//           },
//         }),
//       ],
//     }
//   },
// })

export const api = createTRPCProxyClient<AppRouter>({
  transformer: superjson,
  links: [
    // loggerLink commented out
    //customLink,
    httpBatchLink({
      url: 'http://localhost:4000/trpc',
      headers: Object.fromEntries(headers()),
      fetch(url, options) {
        return fetch(url, {
          ...options,
          credentials: 'include',
        })
      },
    }),
  ],
})

'use server'

import { headers } from 'next/headers'
import type { TRPCLink } from '@trpc/client'
import { loggerLink, httpBatchLink, createTRPCProxyClient } from '@trpc/client'
import superjson from 'superjson'
import type { AppRouter } from '@api/server/router'
import { observable } from '@trpc/server/observable'
import { permanentRedirect } from 'next/navigation'

// export const api = experimental_createTRPCNextAppDirServer<AppRouter>({
//   config() {
//     return {
//       transformer: superjson,
//       links: [
//         loggerLink({
//           enabled: (opts) => {
//             //console.log(opts)
//             return (
//               process.env.NODE_ENV === 'development' ||
//               (opts.direction === 'down' && opts.result instanceof Error)
//             )
//           },
//         }),
//         httpBatchLink({
//           url: 'http://localhost:4000/trpc',
//           headers: Object.fromEntries(headers()),
//           fetch(url, options) {
//             return fetch(url, {
//               ...options,
//               credentials: 'include',
//             })
//           },
//         }),
//       ],
//     }
//   },
// })

export const api = createTRPCProxyClient<AppRouter>({
  transformer: superjson,
  links: [
    // loggerLink commented out
    //customLink,
    httpBatchLink({
      url: 'http://localhost:4000/trpc',
      headers: Object.fromEntries(headers()),
      fetch(url, options) {
        return fetch(url, {
          ...options,
          credentials: 'include',
        })
      },
    }),
  ],
})

Ive been switching between createTRPCProxyClient and experimental_createTRPCNextAppDirServer see above

customLink: Currently not working
export const customLink: TRPCLink<AppRouter> = () => {
  return ({ next, op }) => {
    return observable((observer) => {
      const unsubscribe = next(op).subscribe({
        next(value) {
          observer.next(value)
        },
        error(err) {
          observer.error(err)
          if (err?.data?.code === 'UNAUTHORIZED') {
            console.log('LIAM123') // Works
            permanentRedirect('/login') // Does not work both 'redirect' and 'permanentRedirect' 
          }
        },
        complete() {
          observer.complete()
        },
      })
      return unsubscribe
    })
  }
}

customLink: Currently not working
export const customLink: TRPCLink<AppRouter> = () => {
  return ({ next, op }) => {
    return observable((observer) => {
      const unsubscribe = next(op).subscribe({
        next(value) {
          observer.next(value)
        },
        error(err) {
          observer.error(err)
          if (err?.data?.code === 'UNAUTHORIZED') {
            console.log('LIAM123') // Works
            permanentRedirect('/login') // Does not work both 'redirect' and 'permanentRedirect' 
          }
        },
        complete() {
          observer.complete()
        },
      })
      return unsubscribe
    })
  }
}

Alex / KATT 🐱•6mo ago

so something like this maybe

export const api = createTRPCProxyClient<AppRouter>({
  transformer: superjson,
  links: [
    // loggerLink commented out
    //customLink,
    httpBatchLink({
      url: 'http://localhost:4000/trpc',
      headers(opts) {
        // Any of the passed operations can override the headers
        const headersOverride = opts.opList.find(
          (op) => op.context?.headersOverride,
        ) as Record<string, string> | undefined;

        if (headersOverride) {
          console.log('headersOverride', headersOverride);
          return headersOverride;
        }

        return Object.fromEntries(headers());
      },
      fetch(url, options) {
        return fetch(url, {
          ...options,
          credentials: 'include',
        });
      },
    }),
  ],
});

export const api = createTRPCProxyClient<AppRouter>({
  transformer: superjson,
  links: [
    // loggerLink commented out
    //customLink,
    httpBatchLink({
      url: 'http://localhost:4000/trpc',
      headers(opts) {
        // Any of the passed operations can override the headers
        const headersOverride = opts.opList.find(
          (op) => op.context?.headersOverride,
        ) as Record<string, string> | undefined;

        if (headersOverride) {
          console.log('headersOverride', headersOverride);
          return headersOverride;
        }

        return Object.fromEntries(headers());
      },
      fetch(url, options) {
        return fetch(url, {
          ...options,
          credentials: 'include',
        });
      },
    }),
  ],
});

& this becomes something like

import { TRPCClientError } from '@trpc/client';
import { NextResponse } from 'next/server';
import type { NextRequest } from 'next/server';
import { api } from './app/trpc/server';

// This function can be marked `async` if using `await` inside
export function middleware(request: NextRequest) {
  console.log('Haha LOL 123');
  return api.userRouter.getCurrentUser
    .query(undefined, {
      context: {
        headersOverride: Object.entries(request.headers),
      },
    })
    .catch((err) => {
      if (err instanceof TRPCClientError) {
        if (err.data.code === 'UNAUTHORIZED') {
          return NextResponse.redirect(new URL('/login', request.url));
        }
      }
    });
}

//See "Matching Paths" below to learn more
export const config = {
  matcher: '/dashboard/',
};

import { TRPCClientError } from '@trpc/client';
import { NextResponse } from 'next/server';
import type { NextRequest } from 'next/server';
import { api } from './app/trpc/server';

// This function can be marked `async` if using `await` inside
export function middleware(request: NextRequest) {
  console.log('Haha LOL 123');
  return api.userRouter.getCurrentUser
    .query(undefined, {
      context: {
        headersOverride: Object.entries(request.headers),
      },
    })
    .catch((err) => {
      if (err instanceof TRPCClientError) {
        if (err.data.code === 'UNAUTHORIZED') {
          return NextResponse.redirect(new URL('/login', request.url));
        }
      }
    });
}

//See "Matching Paths" below to learn more
export const config = {
  matcher: '/dashboard/',
};

BillyBob•6mo ago

I can test this.

Alex / KATT 🐱•6mo ago

basically override on demand for middlewares

BillyBob•6mo ago

Thank you very much for helping

Alex / KATT 🐱•6mo ago

the underlying issue seems to be that you can't call headers() in middlewares

BillyBob•6mo ago

Am i likely to be able to get the customLink to work? That way i wouldn't be doing an extra API call on every request

Alex / KATT 🐱•6mo ago

perhaps, i'm not sure

BillyBob•6mo ago

@Alex / KATT 🐱 Edit: Your solution works. At first it was not entering the catch, but that was my fault. btw your solution did solve another issue for me though: I was intermittently getting Error: Invariant: headers() expects to have requestAsyncStorage, in some route page.tsx @Alex / KATT 🐱 - Actually had to make some changes but it worked in the end:

export const api = createTRPCProxyClient<AppRouter>({
  transformer: superjson,
  links: [
    // loggerLink({
    //customLink,
    httpBatchLink({
      url: 'http://localhost:4000/trpc',
      headers(opts) {
        // Any of the passed operations can override the headers
        const headersOverride = opts.opList.find(
          (op) => op.context?.headersOverride,
        )?.context.headersOverride as Record<string, string> | undefined // THIS LINE WAS UPDATED

        if (headersOverride) {
          console.log('headersOverride', headersOverride)
          //console.log('headers', Object.fromEntries(headers()))
          return headersOverride
        }

        return Object.fromEntries(headers())
      },
      fetch(url, options) {
        return fetch(url, {
          ...options,
          credentials: 'include',
        })
      },
    }),
  ],
})

export const api = createTRPCProxyClient<AppRouter>({
  transformer: superjson,
  links: [
    // loggerLink({
    //customLink,
    httpBatchLink({
      url: 'http://localhost:4000/trpc',
      headers(opts) {
        // Any of the passed operations can override the headers
        const headersOverride = opts.opList.find(
          (op) => op.context?.headersOverride,
        )?.context.headersOverride as Record<string, string> | undefined // THIS LINE WAS UPDATED

        if (headersOverride) {
          console.log('headersOverride', headersOverride)
          //console.log('headers', Object.fromEntries(headers()))
          return headersOverride
        }

        return Object.fromEntries(headers())
      },
      fetch(url, options) {
        return fetch(url, {
          ...options,
          credentials: 'include',
        })
      },
    }),
  ],
})

export async function middleware(request: NextRequest) {
  return api.userRouter.getCurrentUser
    .query(undefined, {
      context: {
        headersOverride: Object.fromEntries(request.headers), // entries() changed to fromEntries()
      },
    })
    .then(() => NextResponse.next())
    .catch((err) => {
      if (err instanceof TRPCClientError) {
        if (err.data.code === 'UNAUTHORIZED') {
          console.log('in if')
          return NextResponse.redirect(new URL('/login', request.url))
        }
      }
      return NextResponse.next()
    })
}

export async function middleware(request: NextRequest) {
  return api.userRouter.getCurrentUser
    .query(undefined, {
      context: {
        headersOverride: Object.fromEntries(request.headers), // entries() changed to fromEntries()
      },
    })
    .then(() => NextResponse.next())
    .catch((err) => {
      if (err instanceof TRPCClientError) {
        if (err.data.code === 'UNAUTHORIZED') {
          console.log('in if')
          return NextResponse.redirect(new URL('/login', request.url))
        }
      }
      return NextResponse.next()
    })
}

Alex / KATT 🐱•6mo ago

nice, glad it worked out!

BillyBob•5mo ago

@Alex / KATT 🐱 I think this might be interfereing with POST requests / mutations as there is a content-length mismatch. If you have a quick fix by better understanding that would be helpful. I am working on it now though Yes i am having to do this to get it to work

headers(opts) {
        // Any of the passed operations can override the headers
        const headersOverride = opts.opList.find(
          (op) => op.context?.headersOverride
        )?.context.headersOverride as Record<string, string> | undefined

        

        if (headersOverride) {
          // console.log('headersOverride', headersOverride)
          // console.log('headers', Object.fromEntries(headers()))
          delete headersOverride['content-length']
          delete headersOverride['content-type']
          return headersOverride
        }

        const h = Object.fromEntries(headers())
        delete h['content-length']
        delete h['content-type']

        return h
      }

headers(opts) {
        // Any of the passed operations can override the headers
        const headersOverride = opts.opList.find(
          (op) => op.context?.headersOverride
        )?.context.headersOverride as Record<string, string> | undefined

        

        if (headersOverride) {
          // console.log('headersOverride', headersOverride)
          // console.log('headers', Object.fromEntries(headers()))
          delete headersOverride['content-length']
          delete headersOverride['content-type']
          return headersOverride
        }

        const h = Object.fromEntries(headers())
        delete h['content-length']
        delete h['content-type']

        return h
      }

seems messy also not sure what changed. but now a simple

      headers() {
        return {
          cookie: cookies().toString(),
        }
      },

      headers() {
        return {
          cookie: cookies().toString(),
        }
      },

seems to work