golang http server,can't get post value

func login(rw http.ResponseWriter, req *http.Request) {
	req.ParseForm()

	if req.Method == "GET" {
		fmt.Fprintf(rw, "Error Method")
	} else {
		name := strings.TrimSpace(req.FormValue("userid"))
		fmt.Println("userid:", name)
		fmt.Println("pwd:", req.FormValue("pwd"))
		fmt.Fprintf(rw, "welcome back,%s", req.FormValue("userid"))
	}
}

and i using ASIhttprequst send a from,like this.

[self setRequest:[ASIFormDataRequest requestWithURL:[NSURL URLWithString:@"http://127.0.0.1:8080/login"]]];
[request setPostValue:@"userid" forKey:@"fdfs@jkjlf.cm"];
[request setPostValue:@"pwd" forKey:@"fdsfdsfdkskfjhds"];
[request setRequestMethod:@"POST"];

i got a null value with req.FormValue("userid")

what happend? and how to fix it?

How about this?

req.ParseForm()
req.Form.Get(key)

did you already test it with req.PostFormValue instead of req.FormValue ?

I've found solution with calling ParseMultipartForm before ParseForm, it works for me.

If you make multipart/form-data POST request, ParseForm does not parse request body correctly (this might be a bug). So, use ParseMultipartForm if that is the case.

Or you can call FormValue or PostFormValue directly without calling these parse methods.

I had similar issues using ParseForm. I ended up doing something like this:

type UserRequest struct {
  UserId  string `json:"userid"`
  Pwd     string `json:"pwd"`
}

func login(w http.ResponseWriter, r *http.Request) {
   var ur UserRequest
   decode := json.NewDecoder(r.Body)
   decoder.Decode(&ur)
  
   // Access data via struct
}

Hope that helps!

To extract a value from a post request you have to call r.ParseForm() at first. This parses the raw query from the URL and updates r.Form.

> For POST or PUT requests, it also parses the request body as a form
> and put the results into both r.PostForm and r.Form. POST and PUT body
> parameters take precedence over URL query string values in r.Form.

Now your r.From is a map of all values your client provided. To extract a particular value you can use r.FormValue("<your param name>") or r.Form.Get("<your param name>").

So basically you will have this:

r.ParseForm()
res := r.FormValue("<your param name>")

    // Form contains the parsed form data, including both the URL
    // field's query parameters and the POST or PUT form data.
    // **This field is only available after ParseForm is called.**
    // The HTTP client ignores Form and uses Body instead.
    Form url.Values

    // PostForm contains the parsed form data from POST, PATCH,
    // or PUT body parameters.
    //
    // **This field is only available after ParseForm is called.**
    // The HTTP client ignores PostForm and uses Body instead.
    PostForm url.Values

Make sure the req.Body io.Reader buffer is getting cleared by reading it in some level

ex: ioutil.ReadAll if Body buffer got cleared it will return empty value on FormValue even you ParseForm

Try this buddy.

hope it will work as it works for me

r.FormValue("userid")