nuxt: Cannot read properties of undefined (reading 'content-type') using express js

Environment

Operating System: Linux
Node Version: v16.10.0
Nuxt Version: 3.0.0-27265876.3cd4494
Package Manager: yarn@1.22.17
Bundler: Vite
User Config: serverMiddleware
Runtime Modules: -
Build Modules: -

Describe the bug

serverMiddleware doesn’t work with express.js (4.17.1) and throws “Cannot read properties of undefined (reading 'content-type')” error

Reproduction

Clone a repository with the bug and run it as dev server

$ git clone https://github.com/martiliones/nuxt-express-bug
$ cd nuxt-express-bug && yarn install
$ yarn dev

Open http://localhost:3000/projects/ in your browser

Additional context

I tested serverMiddleware with h3 and it works just fine:

// api/index.js
import { createApp } from 'h3'

const app = createApp()
app.use('/projects', () => JSON.stringify([
    {
      name: 'asdsad',
      type: ['asdsad', 'asdsad']
    }
]))

Logs

Cannot read properties of undefined (reading 'content-type')
  at ServerResponse.getHeader (node:_http_outgoing:597:24)  
  at ServerResponse.res.get (./node_modules/express/lib/response.js:789:15)  
  at ServerResponse.json (./node_modules/express/lib/response.js:263:13)  
  at file://./.nuxt/nitro/index.mjs:139:7  
  at Layer.handle [as handle_request] (./node_modules/express/lib/router/layer.js:95:5)  
  at next (./node_modules/express/lib/router/route.js:137:13)  
  at Route.dispatch (./node_modules/express/lib/router/route.js:112:3)  
  at Layer.handle [as handle_request] (./node_modules/express/lib/router/layer.js:95:5)  
  at ./node_modules/express/lib/router/index.js:281:22  
  at Function.process_params (./node_modules/express/lib/router/index.js:335:12)

About this issue

Original URL
State: closed
Created 3 years ago
Reactions: 4
Comments: 33 (13 by maintainers)

Most upvoted comments

Using the full URL prevents Nitro from making a local call. So it’s a workaround with a performance cost.

danielroe on Jan 20, 2022

Using the direct full URL eg

http://localhost:3000/api/whatever

Instead of

api/whatever

Worked for me …

calumk on Dec 12, 2021

I ended up writing my own router based on h3 that can handle different request methods and route parameters. It’s probably not the best approach, but if anyone wants to use it here it is: router.ts

n3wsw3 on Jan 7, 2022

So is this a bug then? Using the full url works for me but would love to have the url relative

MikeyBeLike on Dec 24, 2021

The problem only seems to exist when the API is used while SSR. Requesting with postman does not throw any errors.

n3wsw3 on Nov 24, 2021

Not sure if that’s the case 🤔 cc @danielroe

manniL on Feb 7, 2023

If you want to debug it, the issue is that express sets the prototype of req/res to be the native Node classes, rather than the unenv-provided classes we’re using in Nuxt. That means the internal object that Node uses to store headers is undefined and can’t be read from.

danielroe on Dec 7, 2021