sessions

package main

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

	"github.com/jonstaryuk/sessions"
)

var key [sessions.KeySize]byte

func main() {
	// Define a type to hold the session data you want to save on the client.
	// Only include the most essential data, since HTTP cookies have limited
	// storage capacity (around 4 KB).
	type Session struct {
		UserID    int
		SessionID string
		Started   time.Time
	}

	// Create a Store when you initialize your server.
	store, err := sessions.NewStore(key)
	if err != nil {
		panic(err)
	}
	store.CookieTemplate = http.Cookie{
		Name:   "myapp_session",
		Path:   "/",
		MaxAge: 7 * 24 * 60 * 60,
	}

	// Save the data to the client when a user successfully logs in.
	http.HandleFunc("/login", func(w http.ResponseWriter, r *http.Request) {
		// ... authenticate the user ...

		sess := Session{
			UserID:    12345,
			SessionID: "example",
			Started:   time.Now(),
		}

		if err := store.SetCookie(w, sess); err != nil {
			log.Println(err)
			http.Error(w, "internal error", http.StatusInternalServerError)
			return
		}

		fmt.Fprintln(w, "OK")
	})

	// Retrieve the data as desired.
	http.HandleFunc("/my_account", func(w http.ResponseWriter, r *http.Request) {
		var sess Session
		if err := store.GetFromCookie(r, &sess); err != nil {
			if err != sessions.ErrMissing {
				log.Println(err)
			}
			http.Error(w, "not logged in", http.StatusForbidden)
			return
		}

		fmt.Fprintf(w, "Logged in as user %d", sess.UserID)
	})
}

Output: