Lesson 37 · Which redirects change the method

Which redirects change the method

The redirect status code decides whether the follow-up repeats your POST or switches to a GET. Today you pin that rule - the one place the 3xx codes genuinely differ.

The goal

Decide the follow-up method and whether to keep the body from the redirect status and original method.

Start here - the target

TO DO

Scenario: Method changes across a redirect

Givena redirect received in response to a POST request

Whenthe follow-up method is decided from the status code

Thena 303 uses GET and drops the body, while a 307 keeps POST and keeps the body

Anda 302 uses GET and drops the body, and a 308 keeps POST and keeps the body

Background

This is the one place the redirect codes genuinely diverge, and it is worth pinning exactly. 303 See Other always switches the follow-up to GET and drops the body

it exists precisely to turn a POST into a GET of some result page. 307 Temporary Redirect and 308 Permanent Redirect are the opposite: they preserve the method and the body, so a POST stays a POST. The older 301 and 302 are messier - the specification says preserve, but browsers historically turned POST into GET, and real clients follow that convention.

So for a POST, a 303 or 302 sends a bodyless GET to the new location, while a 307 or 308 re-sends the whole POST. Getting this right is what keeps a redirect from either losing data or re-submitting a form unexpectedly. It is a small function, but it encodes a genuine and often-misunderstood rule of HTTP.

Make it work

// 303           -> always GET, drop the body
// 307, 308      -> preserve the method AND the body
// 301, 302      -> a POST becomes GET (drop body); GET/HEAD unchanged
func redirectMethod(status int, method string) (newMethod string, keepBody bool) {
  // switch on status; return the method + whether to resend the body
}

CheckpointDONE

The client picks the correct follow-up method and body for each redirect code. Commit and stop here.