如何使用golang或go提交表单后在json中正确获取消息

Question

How to properly get message in json after form submision using golang. Am just trying golang today for the first time.

Here is what am trying to achieve with golang:

In php for instance I can echo/print a json message after user submmitted a form and can then access it from the front end

Eg.

  if($everything == 'ok'){
 $messages = [
      'message' => 'User Registered successfully'
    ];
   echo json_encode($messages);
exit();
  }

Please How do I do this with golang.

The code below works fine by inserting records to database. Upon a successful insert, it display a success message in the code below and everything is working fine.

res.Write([]byte("User Registered successfully!" +username))

Here is my qusetion: How do I get json response of the successful message so that I can access it from my front end just like in php code above.

I have tried

messageJson := `{"message": "User Registered successfully"}`
jsonresult_send := json.Marshal(messageJson)

return jsonresult_send

But it displays error too many argument to return

Here is the entire code



package main

import "database/sql"
import _ "github.com/go-sql-driver/mysql"

import "net/http"
import "fmt"
import "encoding/json"

var db *sql.DB
var err error



type MessageInfo struct {
  Message string
}



func signupPage(res http.ResponseWriter, req *http.Request) {
    if req.Method != "POST" {
        http.ServeFile(res, req, "signupjson.html")
        return
    }



        username := req.FormValue("username")
    password := req.FormValue("password")



    var user string
         err := db.QueryRow("SELECT username FROM users WHERE username=?", username).Scan(&user)


    switch {
    case err == sql.ErrNoRows:
        _, err = db.Exec("INSERT INTO users(username, password) VALUES(?, ?)", username, password)
        if err != nil {
            http.Error(res, "insert error, unable to create your account.", 500)
            return
        }

res.Write([]byte("User Registered successfully!" +username))

// get json response message

messageJson := `{"message": "User Registered successfully"}`
jsonresult_send := json.Marshal(messageJson)

return jsonresult_send

        return
    default:
        http.Redirect(res, req, "/", 301)
    }
}



func homePage(res http.ResponseWriter, req *http.Request) {
    http.ServeFile(res, req, "index.html")
}

func main() {
    db, err = sql.Open("mysql", "root:@/golang44")
    if err != nil {
        panic(err.Error())
    }
    defer db.Close()

    err = db.Ping()
    if err != nil {
        panic(err.Error())
    }

    http.HandleFunc("/signupjson", signupPage)
    http.HandleFunc("/", homePage)
        fmt.Println("Listening on 127.0.0.1:8088")
    http.ListenAndServe(":8088", nil)
}

Answer 1

If I understood correctly, what you need is this:

func GetPeople(w http.ResponseWriter, r *http.Request) {
    json.NewEncoder(w).Encode(people)
}

In your case, you could solve it in two ways:

1. With a struct

type Info struct {
    Message string `json:"message"`
}

func MyHandler(w http.ResponseWriter, r *http.Request) {
    ... Some processing here ...

    info := Info{Message: "User Registered successfully"}
    json.NewEncoder(w).Encode(info)
}

1. With a map

func MyHandler(w http.ResponseWriter, r *http.Request) {
    ... Some processing here ...

    info := map[string]string{"message": "User Registered successfully"}
    json.NewEncoder(w).Encode(info)
}

If anyone can test to look for some syntax error I appreciate it.