Why POST redirects to GET and PUT redirects to PUT?

Question

I am using express 4.13.3 (latest) and following code:

var express = require('express')

var app = express()

app.get('/test', function (req, res, next) {
  res.send('hello!')
})

app.post('/test', function (req, res, next) {
  res.redirect('/test')
})

app.put('/test', function (req, res, next) {
  res.redirect('/test')
})

app.listen(5001)

// GET /test -> 'hello!'
// POST /test -> 'hello!'
// PUT /test -> ERR_TOO_MANY_REDIRECTS

POST redirects to GET but PUT redirects to PUT. Is it possible to make PUT redirect to GET (same as POST)?

Answer 1

Before diving in the details, below is one way of how you could solve the problem:

app.put('/test', function(req, res, next) {
    res.redirect(303, '/test') // Notice the 303 parameter
})

By default Express uses HTTP code 302 for the redirect. According to the HTTP specification, this prevents POST/PUT requests from being redirected as POST/PUT requests and explains what you observed in your code:

If the 302 status code is received in response to a request other than GET or HEAD, the user agent MUST NOT automatically redirect the request unless it can be confirmed by the user, since this might change the conditions under which the request was issued.

On the other hand, if you use a 303 redirect, the POST/PUT request is allowed to be redirected as a POST/PUT request as explained in this great SO answer:

303: Redirect for undefined reason. Typically, 'Operation has completed, continue elsewhere.' Clients making subsequent requests for this resource should not use the new URI. Clients should follow the redirect for POST/PUT/DELETE requests.