Redirect status code causing no redirect to occur

[jonnow]

Hey, I was looking at the fastify-session authentication example when I noticed this.
I have a post request to /login that does a redirect to the homepage. Without setting a status code this works without any issue. However, I wanted to send a status code along to then change the UI if it's a specific code (say 213 for arguments sake).

However, when I try to include a status code with the reply things seem to break as the redirect no longer happens.

Can anyone let me know if this is a known issue or perhaps I'm not doing something right with fastify.redirect(statusCode, url)?

// Homepage GET
  fastify.get('/', (request, reply) => {
    reply.type('text/html')
    reply.send(defaultPage(request.session.authenticated))
  });

// Login POST
fastify.post('/login', (request, reply) => {
    const { email, password } = request.body
    if (password === 'abcdef') {
      request.session.authenticated = true
      reply.redirect(213, '/')
      //reply.redirect('/') // <- This way works and redirects to the '/' GET but without the custom status code
    } else {
      reply.redirect(401, '/login')
    }
  });

[metcoder95]

Hey! Can we know which HTTP Status code you were using?
It is important to respect the HTTP 3xx redirect semantics as that will indicate to the browser how to handle the redirect and what to do next. If you're trying to execute a redirect by replying with a, e.g. 213, as it falls into the range >=200 < 300 for instance the browser will understand it is ok and nothing else has to be done, as the server indicated so.

For a redirect for being successful, it should fall in the range of > 300 depending on your feature need.

[metcoder95]

By default, fastify uses 302 as redirection status code

[jonnow]

I was trying 213 which didn't redirect. I've just tried it with 302 and that does redirect to the '/' route. However, the request.statusCode is still undefined rather than being 302. Should I be able to see this status code in the incoming request to '/'

[metcoder95]

By HTTP specs, the status code is not part of the HTTP Request semantics. As the Status Code is part of the HTTP Response and will remain with the browser, and then the browser executes the redirection constructing a new HTTP Request.

If you want to share data between redirects, the most common option is to share it by the query string of the redirected path (e.g. reply.redirect('/redirect?myprop=myvalue'))

[jonnow]

Great, thank you!