How to remove 'text/plain;charset=UTF-8' from content-type header?

Hi, I am trying to send a post request to PostgREST to invoke a stored procedure:

  const data = await $fetch('http://http-logger:3001/rpc/test_proc', {
    method: 'post',
    headers: {
      Prefer: 'params=single-object',
      Accept: 'application/json',
      'Content-Type':  'application/json'
    },
    body: {some: 'json'}
})

Results in this request:

POST /rpc/test_proc HTTP/1.1
host: http-logger:3001
connection: keep-alive
prefer: params=single-object
accept: application/json
content-type: application/json, text/plain;charset=UTF-8
accept-language: *
sec-fetch-mode: cors
user-agent: undici
accept-encoding: gzip, deflate
content-length: 15


{"some":"json"}

I need to remove the ‘text/plain;charset=UTF-8’ part from the content-type. Is this possible? Should it even be there as I have explicitly defined the content-type header? Many thanks Ian

[phorcys420]

Actually, it is only an issue with undici fetch in ohmyfetch context, here’s a snippet to test it out :

import http from "node:http";

import { $fetch } from "ohmyfetch/node";

const server = http.createServer((req, res) => {
   console.log(req.headers);

  res.end();
});

server.listen(8000);

for(const fetchImpl of [fetch, $fetch]) {
	await fetchImpl("http://localhost:8000", {
		body: { lo: "dibidon" },

		headers: {
			"content-type": "application/json"
		},

		method: "POST"
	});
}

globalThis.fetch:

{
  host: 'localhost:8000',
  connection: 'keep-alive',
  'content-type': 'application/json',
  accept: '*/*',
  'accept-language': '*',
  'sec-fetch-mode': 'cors',
  'user-agent': 'undici',
  'accept-encoding': 'gzip, deflate',
  'content-length': '0'
}

ohmyfetch:

{
  host: 'localhost:8000',
  connection: 'keep-alive',
  'content-type': 'application/json, text/plain;charset=UTF-8',
  accept: 'application/json',
  'accept-language': '*',
  'sec-fetch-mode': 'cors',
  'user-agent': 'undici',
  'accept-encoding': 'gzip, deflate',
  'content-length': '16'
}

I tried on node 16 and I had no issue with node-fetch. So, it’s an issue with ohmyfetch’s implementation of undici fetching. It doesn’t happen with unjs/node-fetch-native alone. I also realized it doesn’t happen if you omit the body.

[phorcys420]

I can confirm that this is only an issue with undici fetch (globalThis.fetch)