Why isn't my GoLang POST request being populated with data?

func forwarderHandlerFunc(w http.ResponseWriter, r *http.Request) {
	client := &http.Client{}
	u, _ := url.Parse(r.RequestURI)
	req, _ := http.NewRequest(r.Method, fmt.Sprintf("%s%s", apiUrl, u.Path), r.Body)
	fmt.Printf(fmt.Sprintf("%s\n", nutils.ReaderToString(req.Body)))
	resp, _ := client.Do(req)
	resp.Write(w)
}

I am trying to forward an incoming HTTP request to another endpoint, while copying the body, including POST/PUT form data into the new request.

However, it doesn't seem to work, even if the Body seems to print out correct with data.

Print output is:

> email=meh%!g(MISSING)mail.com

How can I fix it?

Edit: Added more debug info, this time, printing out the output of resp

func forwarderHandlerFunc(w http.ResponseWriter, r *http.Request) {
	client := &http.Client{}
	u, _ := url.Parse(r.RequestURI)

	req, _ := http.NewRequest(r.Method, fmt.Sprintf("%s%s", apiUrl, u.Path), r.Body)
    fmt.Printf(fmt.Sprintf("%s\n", nutils.ReaderToString(req.Body)))

	resp, _ := client.Do(req)
	b,_ := ioutil.ReadAll(resp.Body)
	fmt.Printf(fmt.Sprintf("%s\n", nutils.BytesToString(b)))

	resp.Write(w)
}

> $ go install && gom-proxy-forwarder run --listen localhost:5002 --api-url http://localhost:5001
> email=meh2%!g(MISSING)mail.com
> {
> "email": null
> }

It should not be null. It should be meh@gmail.com

Got it. The problem was my endpoint in Python's Flask server does not support chunked encoding, which Go's Request insists on.

When I manually specified the ContentLength like req.ContentLength = 25, it worked.

Lesson learnt: It might not always be your Go code be the problem.

You may want to set the request content type

req.Header.Set("Content-Type", "application/x-www-form-urlencoded")

reference http://golang.org/src/net/http/client.go?s=14234:14316#L450

1. To fix your print output you need to change this:

    fmt.Printf(fmt.Sprintf("%s\n", nutils.ReaderToString(req.Body)))
   

   Into this:

    fmt.Printf("%s", fmt.Sprintf("%s\n", nutils.ReaderToString(req.Body)))
   

   Or this:

    fmt.Println(fmt.Sprintf("%s\n", nutils.ReaderToString(req.Body)))
   

2. By printing out the request body you are consuming it. Use a TeeReader:

    req, _ := http.NewRequest(r.Method, fmt.Sprintf("%s%s", apiUrl, u.Path), io.TeeReader(r.Body, os.Stdout))
   

   And get rid of the nutils.ReaderToString call. You can only read once from a Reader (unless it's also a Seeker but then you still need to Seek it before reusing it)