app.render from '/' to '/something' do not work

[6be709c0]

Bug report

Describe the bug

I use the parameters [langs] in my project to use multi lang.
So If I can easily access: /fr /fr/about, /en, /en/about

Thing is, I want my default locale to redirect to / and /about.
So I use a custom router to do that and the following method:

app.render(req, res, `/en/${pathname.slice(1)}`, query);

But when I access to /, it doesn't redirect me in the app into /en.
However, it work with /en/about > /about, and it work within the app.

To Reproduce

• Use [lang] as parameters and have a [lang] directory
• server.js

const { createServer } = require("http");
const { parse } = require("url");
const next = require("next");

// locales =  ['en','fr']
const { locales } = require("./translations/config");

const dev = process.env.NODE_ENV !== "production";
const app = next({ dev });
const handle = app.getRequestHandler();

app.prepare().then(() => {
  createServer((req, res) => {
    // Be sure to pass `true` as the second argument to `url.parse`.
    // This tells it to parse the query portion of the URL.
    const parsedUrl = parse(req.url, true);
    const { pathname, query } = parsedUrl;

    const pathNameSplit = pathname.split("/");
    if (
      (pathNameSplit[pathNameSplit.length - 1].indexOf(".") < 0 &&
        pathname.indexOf("_next/webpack-hmr") < 0) ||
      !pathname
    ) {
      if (locales.indexOf(pathname.slice(1, 3)) < 0) {
        // Display english version if the lang is not detected
        console.log("Render", `/en/${pathname.slice(1)}`);
        app.render(req, res, `/en/${pathname.slice(1)}`, query); // Here is my issue /en is not redirected to /en in the app but to /
      } else if (pathname.slice(1, 4) === "en/" || pathname == "/en") {
        res.writeHead(301, { Location: `/${pathname.slice(4)}` });
        return res.end();
      }
    }
    handle(req, res, parsedUrl);
  }).listen(3001, err => {
    if (err) throw err;
    console.log("> Ready on http://localhost:3001");
  });
});

[timneutkens]

This is more so a question which belongs on https://spectrum.chat/next-js. When creating issues please make sure a clear and concise full reproduction is provided otherwise it becomes incredibly hard to help.

I guess this specifically will be covered by #9081

[balazsorban44]

This issue has been automatically locked due to no recent activity. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.