http: response.setHeaders()

[marco-ippolito]

from: #46082
I've extracted from res.writeHead the part where it sets multiple headers into res.setHeaders.
I've removed this part in writeHead:
if (k === undefined && this._header) { throw new ERR_HTTP_HEADERS_SENT('render'); }
because since #45508 it never enters that condition.

[nodejs-github-bot]

Review requested:

• @nodejs/http
• @nodejs/net

[mcollina]

lgtm

[marco-ippolito]

One problem that emerged is that I cannot check if (headers instanceof Headers) because importing Headers creates a circular dependency with undici. I need to check it in another way. Maybe if headers has a keys and get function, this would also allow Maps

[ShogunPanda]

One problem that emerged is that I cannot check if (headers instanceof Headers) because importing Headers creates a circular dependency with undici. I need to check it in another way. Maybe if headers has a keys and get function, this would also allow Maps

+1 on this. I would also outline in the docs somehow.

[ShogunPanda]

Little bit. Rest looks fine.

[jimmywarting]

One problem that emerged is that I cannot check if (headers instanceof Headers) because importing Headers creates a circular dependency with undici. I need to check it in another way. Maybe if headers has a keys and get function, this would also allow Maps

Hmm confused as to why you can't import Headers 😕
Don't know how NodeJS/undici creates a circular dependency. (haven't really dug into the code. But if that's they way it got to be then OK.

Maybe that was the reason why you could not do something similar to:

res.setHeaders = function (headers) {
  if (headers instanceof Headers === false) headers = new Headers(headers)
  if (headers[symbol.toStringTag] !== 'Headers') headers = new Headers(headers) // or this
  
  for (const [key, value] of headers) {
    this.setHeader(key, value)
  }
}

?

[marco-ippolito]

@jimmywarting it created a circular dependency because Headers is export by Undici which requires the http module. (the globalThis.Headers is forbidden)
Since Headers is basically an extension of Map I think it was a good idea to allow Map.

[RafaelGSS]

@marco-ippolito this didn't land cleanly on v19.x-staging because you are removing ERR_HTTP_HEADERS_SENT without removing it from the top (the v19.x doesn't include the #45508).

I'll open a backport for you.

[RafaelGSS]

Actually, I can't. Your test relies on a feature available only on main requireHostHeader (semver-major). Can you create a manual backport?

[juanarbol]

This is breaking test/parallel/test-http-write-head.js in v18.x

/usr/local/opt/python@3.10/bin/python3.10 tools/test.py  --mode=release \                                                                                                                      
                 \                                                                                                                                                                             
                --skip-tests= \                                                                                                                                                                
                default \                                                                                                                                                                      
                addons js-native-api node-api                                                                                                                                                  
=== release test-http-write-head ===                                                                                                                                                           
Path: parallel/test-http-write-head                                                                                                                                                            
node:assert:124                                                                                                                                                                                
  throw new AssertionError(obj);                                                                                                                                                               
  ^

AssertionError [ERR_ASSERTION]: Missing expected exception (Error).
    at Server.<anonymous> (/Users/juan/GitHub/node/test/parallel/test-http-write-head.js:56:10) 
    at Server.<anonymous> (/Users/juan/GitHub/node/test/common/index.js:446:15)
    at Server.emit (node:events:513:28)
    at parserOnIncoming (node:_http_server:1069:12)
    at HTTPParser.parserOnHeadersComplete (node:_http_common:119:17) {
  generatedMessage: false,
  code: 'ERR_ASSERTION',
  actual: undefined,
  expected: {
    code: 'ERR_HTTP_HEADERS_SENT',
    name: 'Error',
    message: 'Cannot render headers after they are sent to the client'
  },
  operator: 'throws'
}

[marco-ippolito]

I have created a manual backport to 19.x #46272, should I create another for 18.x?

[juanarbol]

I have created a manual backport to 19.x #46272, should I create another for 18.x?

It would great! Thanks!