go - 无法按键获取 gorilla session 值

Question

我无法通过这种方式从 session 中获取值，它是nil:

session := initSession(r)
valWithOutType := session.Values[key]

完整代码:

package main

import (
    "fmt"
    "github.com/gorilla/mux"
    "github.com/gorilla/sessions"
    "log"
    "net/http"
)

func main() {
    rtr := mux.NewRouter()
    rtr.HandleFunc("/setSession", handler1).Methods("GET")
    rtr.HandleFunc("/getSession", handler2).Methods("GET")
    http.Handle("/", rtr)
    log.Println("Listening...")
    http.ListenAndServe(":3000", http.DefaultServeMux)
}

func handler1(w http.ResponseWriter, r *http.Request) {
    SetSessionValue(w, r, "key", "value")
    w.Write([]byte("setSession"))
}

func handler2(w http.ResponseWriter, r *http.Request) {
    w.Write([]byte("getSession"))
    value := GetSessionValue(w, r, "key")
    fmt.Println("value from session")
    fmt.Println(value)
}

var authKey = []byte("secret") // Authorization Key

var encKey = []byte("encKey") // Encryption Key

var store = sessions.NewCookieStore(authKey, encKey)

func initSession(r *http.Request) *sessions.Session {
    store.Options = &sessions.Options{
        MaxAge:   3600 * 1, // 1 hour
        HttpOnly: true,
    }
    session, err := store.Get(r, "golang_cookie")
    if err != nil {
        panic(err)
    }

    return session
}

func SetSessionValue(w http.ResponseWriter, r *http.Request, key, value string) {
    session := initSession(r)
    session.Values[key] = value
    fmt.Printf("set session with key %s and value %s\n", key, value)
    session.Save(r, w)
}

func GetSessionValue(w http.ResponseWriter, r *http.Request, key string) string {
    session := initSession(r)
    valWithOutType := session.Values[key]
    fmt.Printf("valWithOutType: %s\n", valWithOutType)
    value, ok := valWithOutType.(string)
    if !ok {
        fmt.Println("cannot get session value by key: " + key)
    }
    return value
}

输出:

myMac ~/forStack/session $ go run ./session.go
2015/01/30 16:47:26 Listening...

首先我打开 url http://localhost:3000/setSession 并获得输出:

set session with key key and value value

然后我打开 url http://localhost:3000/getSession 并获得输出:

valWithOutType: %!s(<nil>)
cannot get session value by key: key
value from session

为什么 valWithOutType 是 nil，尽管我将它设置为请求 /setSession？

更新

我根据@isza 的回答更改了代码，但是 session 值仍然是nil。

package main

import (
    "fmt"
    "github.com/gorilla/mux"
    "github.com/gorilla/sessions"
    "log"
    "net/http"
)

func main() {
    rtr := mux.NewRouter()
    rtr.HandleFunc("/setSession", handler1).Methods("GET")
    rtr.HandleFunc("/getSession", handler2).Methods("GET")
    http.Handle("/", rtr)
    log.Println("Listening...")
    store.Options = &sessions.Options{
        MaxAge:   3600 * 1, // 1 hour
        HttpOnly: true,
        Path:     "/", // to match all requests
    }
    http.ListenAndServe(":3000", http.DefaultServeMux)

}

func handler1(w http.ResponseWriter, r *http.Request) {
    SetSessionValue(w, r, "key", "value")
    w.Write([]byte("setSession"))
}

func handler2(w http.ResponseWriter, r *http.Request) {
    w.Write([]byte("getSession"))
    value := GetSessionValue(w, r, "key")
    fmt.Println("value from session")
    fmt.Println(value)
}

var authKey = []byte("secret") // Authorization Key

var encKey = []byte("encKey") // Encryption Key

var store = sessions.NewCookieStore(authKey, encKey)

func initSession(r *http.Request) *sessions.Session {
    session, err := store.Get(r, "golang_cookie")
    if err != nil {
        panic(err)
    }
    return session
}

func SetSessionValue(w http.ResponseWriter, r *http.Request, key, value string) {
    session := initSession(r)
    session.Values[key] = value
    fmt.Printf("set session with key %s and value %s\n", key, value)
    session.Save(r, w)
}

func GetSessionValue(w http.ResponseWriter, r *http.Request, key string) string {
    session := initSession(r)
    valWithOutType := session.Values[key]
    fmt.Printf("valWithOutType: %s\n", valWithOutType)
    value, ok := valWithOutType.(string)
    if !ok {
        fmt.Println("cannot get session value by key: " + key)
    }
    return value
}

Answer 1

您可能在使用 get 方法在初始化 session 函数中执行的操作会再次重新启动整个 session ，因此每次执行此操作时 session 都是空的。我对您所写的内容进行了快速破解，以向您展示错误所在。请绕过这个例子!

package appSession

import (        
    "net/http"
    "fmt"
    "log"
    "github.com/gorilla/sessions"    
)

var appSession *sessions.Session;

var authKey = []byte("qwer")
var encKey = []byte("asdf")

var store = sessions.NewCookieStore(authKey, encKey)    

func initSession(r *http.Request) *sessions.Session {

    log.Println("session before get", appSession)

    if appSession != nil {    
        return appSession;    
    }

    session, err := store.Get(r, "golang_cookie")
    appSession = session;

    log.Println("session after get", session)
    if err != nil {
        panic(err)
    }
    return session
}

func SetSessionValue(w http.ResponseWriter, r *http.Request, key, value string) {
    session := initSession(r)
    session.Values[key] = value
    fmt.Printf("set session with key %s and value %s\n", key, value)
    session.Save(r, w)
}

func GetSessionValue(w http.ResponseWriter, r *http.Request, key string) string {   
    session := initSession(r)
    valWithOutType := session.Values[key]
    fmt.Printf("valWithOutType: %s\n", valWithOutType)
    value, ok := valWithOutType.(string)
    log.Println("returned value: ", value);

    if !ok {
        fmt.Println("cannot get session value by key: " + key)
    }
    return value
}