dongou3158 2019-01-20 10:51
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如何从golang中读取cookie？

I set a cookie from javascript such as :

setCookie("appointment", JSON.stringify({
                appointmentDate: selectedDay.date,
                appointmentStartMn: appointment.mnRange[0],
                appointmentId: appointment.id || 0,
                appointmentUserId: appointment.user.id || 0
          })
);

After cookie is set I want to redirect the user to a booking page :

window.location.href = "https://localhost:8080/booking/"

The setCookie function :

function setCookie(cookieName, cookieValue) {
    document.cookie = `${cookieName}=${cookieValue};secure;`;
}

I'd like to retrieve that cookie from my go backend but I can't figure out how to do this. I've read about this question since I've never used cookies before but the answers seems to tell that I don't have to do much aside from setting document.cookie.

In my browser storage I can see the cookie is indeed set as expected.

In my go backend I want to print the cookie :

r.HandleFunc("/booking/", handler.serveTemplate)

func (handler *templateHandler) serveTemplate(w http.ResponseWriter, r *http.Request) {
    c, err := r.Cookie("appointment")
    if err != nil {
        fmt.Println(err.Error())
    } else {
        fmt.Println(c.Value)
    }
}

//output http: named cookie not present

What is the specific I am missing ? I think I'm confusing local/http cookie but how to achieve the reading of client set cookies ?

UPDATE (see answer for more)

It has nothing to do with golang. My :

appointmentDate: selectedDay.date

What formatted as 2019-01-01 and - is not a valid character that can be send to the backend. It worked into my browser, but it needs to be URI encoded to be passed.

So this did the trick : 

`${cookieName}=${encodeURIComponent(cookieValue)};secure;` + "path=/";`

And in go (didn't catch err here to save space) :

cookie, _ := r.Cookie("appointment")
data, _ := url.QueryUnescape(cookie.Value)
  • 写回答

1条回答 默认 最新

  • dongtiao2105 2019-01-20 12:12
    关注

    A better way would be to encode your json into base64 for example. I made a working example...

    main.go

    package main

import (
    "encoding/base64"
    "encoding/json"
    "fmt"
    "io"
    "io/ioutil"
    "net/http"
)

// Contains everything about an appointment
type Appointment struct {
    Date    string `json:"appointmentDate"`    // Contains date as string
    StartMn string `json:"appointmentStartMn"` // Our startMn ?
    ID      int    `json:"appointmentId"`      // AppointmentId
    UserID  int    `json:"appointmentUserId"`  // UserId
}

func main() {
    handler := http.NewServeMux()

    // Main request
    handler.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
        fmt.Printf("Requested /
")

        // set typical headers
        w.Header().Set("Content-Type", "text/html")
        w.WriteHeader(http.StatusOK)

        // Read file
        b, _ := ioutil.ReadFile("index.html")
        io.WriteString(w, string(b))
    })

    // booking request
    handler.HandleFunc("/booking/", func(w http.ResponseWriter, r *http.Request) {
        fmt.Printf("Requested /booking/
")

        // set typical headers
        w.Header().Set("Content-Type", "text/html")
        w.WriteHeader(http.StatusOK)

        // Read cookie
        cookie, err := r.Cookie("appointment")
        if err != nil {
            fmt.Printf("Cant find cookie :/
")
            return
        }

        fmt.Printf("%s=%s
", cookie.Name, cookie.Value)

        // Cookie data
        data, err := base64.StdEncoding.DecodeString(cookie.Value)
        if err != nil {
            fmt.Printf("Error:", err)
        }

        var appointment Appointment
        er := json.Unmarshal(data, &appointment)
        if err != nil {
            fmt.Printf("Error: ", er)
        }

        fmt.Printf("%s, %s, %d, %d
", appointment.Date, appointment.StartMn, appointment.ID, appointment.UserID)

        // Read file
        b, _ := ioutil.ReadFile("booking.html")
        io.WriteString(w, string(b))
    })

    // Serve :)
    http.ListenAndServe(":8080", handler)
}

    index.html

    <html>
    <head>
        <title>Your page</title>
    </head>
<body>
    Setting cookie via Javascript

    <script type="text/javascript">
    window.onload = () => {
        function setCookie(name, value, days) {
            var expires = "";
            if (days) {
                var date = new Date();
                date.setTime(date.getTime() + (days*24*60*60*1000));
                expires = "; expires=" + date.toUTCString();
            }
            document.cookie = name + "=" + btoa((value || ""))  + expires + "; path=/";
        }

        setCookie("appointment", JSON.stringify({
                    appointmentDate: "20-01-2019 13:06",
                    appointmentStartMn: "1-2",
                    appointmentId: 2,
                    appointmentUserId: 3
            })
        );

        document.location = "/booking/";
    }
    </script>
</body>

    booking.html

    <html>
    <head>
        <title>Your page</title>
    </head>
<body>
    Your booking is okay :)
</body>
    本回答被题主选为最佳回答 , 对您是否有帮助呢?
    评论

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