Get headers in a 302 response

[sralloza]

I'm trying to get the response headers from a 302 response and so far I'm unable to.

It seems that due to the http client returning the redirect error the validators aren't applied, so the headers are not copied. Is there any other way to to this?

This is the code I used for testing:

package main

import (
	"context"
	"errors"
	"fmt"
	"net/http"

	"github.com/carlmjohnson/requests"
)

var (
	errRedirect = errors.New("redirect intercepted")
)

func main() {
	myClient := *http.DefaultClient
	myClient.CheckRedirect = func(req *http.Request, via []*http.Request) error {
		return errRedirect
	}

	statusCodes := []int{200, 302}

	for _, statusCode := range statusCodes {
		headers := map[string][]string{}
		err := requests.URL(fmt.Sprintf("http://httpbin.org/status/%d", statusCode)).
			Client(&myClient).
			CopyHeaders(headers).
			CheckStatus(statusCode).
			Fetch(context.Background())

		if err != nil && !errors.Is(err, errRedirect) {
			panic(err)
		}
		fmt.Printf("Headers with %d: %#v\n", statusCode, headers)
	}

}

Output:

Headers with 200: map[string][]string{"Access-Control-Allow-Credentials":[]string{"true"}, "Access-Control-Allow-Origin":[]string{"*"}, "Connection":[]string{"keep-alive"}, "Content-Length":[]string{"0"}, "Content-Type":[]string{"text/html; charset=utf-8"}, "Date":[]string{"Wed, 10 Apr 2024 08:21:27 GMT"}, "Server":[]string{"gunicorn/19.9.0"}}
Headers with 302: map[string][]string{}

Thanks in advance.

[sralloza]

And once again, a little bit of extra investigation time resolved the issue. The solution is to return http.ErrUseLastResponse in CheckRedirect instead of a custom error.

myClient.CheckRedirect = func(req *http.Request, via []*http.Request) error {
  return http.ErrUseLastResponse
}

[earthboundkid]

Did you see requests.NoFollow? I'm not 100% sure, but it sounds like it would do the thing you want.