Web server on Go apparently is not creating new requests

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Web server on Go apparently is not creating new requests

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#1 by (3 votes)
#2 by (0 votes)

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I'm now starting to develop in Go, and I'm currently studying Go for Web development, so through examples I've started a simple server in Go:

package main

import (
  "fmt"
  "log"
  "net/http"
  "time"

  "github.com/gorilla/mux"
)

var Nome string

func SetNewName(w http.ResponseWriter, r *http.Request){
    fmt.Println("Old Name: "+Nome)
    Nome = r.PostFormValue("nome")
    fmt.Println("New Name: "+Nome+" \n")
    w.Write([]byte("OK"))
}

//Entry point of the program
func main() {
    r := mux.NewRouter()

    fs := http.FileServer(http.Dir("public"))
    r.Handle("/", fs)

    r.HandleFunc("/teste-post", SetNewName).Methods("POST")  

    srv := &http.Server{
        Handler:      r,
        Addr:         ":8000",
        WriteTimeout: 15 * time.Second,
        ReadTimeout:  15 * time.Second,
   }

   log.Fatal(srv.ListenAndServe())
}

In the public folder I have a simple index.html file, where:

1) Request jQuery
2) It has a form

  <form id="frm-post-teste">
        <input type="text" name="nome">
        <input type="submit" id="btn-send" value="Enviar">
  </form>

3) And this script:

$("#btn-send").click(function(e){
  e.preventDefault();

  $.ajax({
    type: "POST",
    url: window.location.origin+"/teste-post",
    data: $("#frm-post-teste").serialize(),
    dataType: "JSON"
  }).done(function(data){
    console.log(data)
  });

});

The problem I've been facing is : Even requests from different browsers, from different devices, and even requests made for this example hosted on DigitalOcean, all display strange behavior, apparently the only application creates a connection because the Name variable has the value of the last stored request, even though they are different requests made by different clients.

This behavior has left me extremely confused because the code is simple and I do not know where the error is coming from.

http golang webserver

asked by anonymous 14.06.2017 / 20:13

2 answers

0

You have declared the Name variable in global context:

var Nome string

If you want to have different contexts, you need to do some session control.

It seems Gorilla can help with this:

link

14.06.2017 / 21:10

Trigger for update before insert LinkedIn profile plugin on website

score 3 · Accepted Answer

This is because of where the variable is defined, when you define:

var Nome string

It becomes global, accessible to everything, so not just a connection.

Doing:

curl -X POST -d "nome=inkeliz" 127.0.0.1:8000/teste-post

Return:

Old Name:
New Name: inkeliz

Then:

curl -X POST -d "nome=x" 127.0.0.1:8000/teste-post

Return:

Old Name: inkeliz
New Name: x

The way to get around this is to set the local variable, in this case you could do:

func SetNewName(w http.ResponseWriter, r *http.Request){
    var nome string
    //...

This will result in:

Old Name:
New Name: inkeliz

Old Name:
New Name: x

Another option would be to simply use := , as in:

func SetNewName(w http.ResponseWriter, r *http.Request){

    nome := r.PostFormValue("nome")

    fmt.Println("New Name: "+nome+" \n")
    w.Write([]byte("OK"))

}