进行HTTP表单解析-返回空的slice / empty值？

Question

I have written a simple web application in Go that needs to read values of an HTTP form (username, password) etc. However, I found that the values were empty when printed. len(r.Form) and len(r.Form["password"]) both return 0.

I have called r.ParseForm() in the application before trying to read the fields and I'm using Postman to send the requests. Tested on both Linux and macOS.

The code I am using to test this is some example code from the Astaxie golang web tutorial. I have attached my Postman request. It looks like this so far:

package main

import (
    "fmt"
    "html/template"
    "log"
    "net/http"
    "strings"
    "time"
)

func sayhelloName(w http.ResponseWriter, r *http.Request) {
    r.ParseForm() //Parse url parameters passed, then parse the response packet for the POST body (request body)
    // attention: If you do not call ParseForm method, the following data can not be obtained form
    fmt.Println(r.Form) // print information on server side.
    fmt.Println("path", r.URL.Path)
    fmt.Println("scheme", r.URL.Scheme)
    fmt.Println(r.Form["url_long"])
    for k, v := range r.Form {
        fmt.Println("key:", k)
        fmt.Println("val:", strings.Join(v, ""))
    }
    fmt.Fprintf(w, "Hello astaxie!") // write data to response
}

func login(w http.ResponseWriter, r *http.Request) {
    fmt.Println("method:", r.Method) //get request method
    if r.Method == "GET" {
        t, _ := template.ParseFiles("login.gtpl")
        t.Execute(w, nil)
    } else {
        r.ParseForm()
        time.Sleep(3 * time.Second)
        // logic part of log in
        fmt.Println("username:", len(r.Form))
        fmt.Println("password:", len(r.Form["password"]))
    }

}

func main() {
    http.HandleFunc("/", sayhelloName) // setting router rule
    http.HandleFunc("/login", login)
    err := http.ListenAndServe(":9090", nil) // setting listening port
    if err != nil {
        log.Fatal("ListenAndServe: ", err)
    }
}

Any suggestions on what to do next?

Thanks!

Answer 1

try changing the content-type on your Postman request from form-data to x-www-form-urlencoded

Because according to the docs on r.ParseForm() the body won't be parsed unless it's x-www-form-urlencoded

For other HTTP methods, or when the Content-Type is not application/x-www-form-urlencoded, the request Body is not read, and r.PostForm is initialized to a non-nil, empty value.