为什么我的GoLang POST请求没有填充数据？

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
", 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
", nutils.ReaderToString(req.Body)))

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

   Into this:

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

   Or this:

   fmt.Println(fmt.Sprintf("%s
   ", 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)