如何使用Go登录以使用您的Google日历？

Question

I am new to GO and APIs and I am making a back end using GO. the user should be able to login using his/her google account and modifies his calendar. I opened the sample on this link Google Quickstart

but the way I get the client is by the keys google gives it to me how should I make the user login and get his calendar

Answer 1

You'll need to do something like:

import (
    "crypto/rand"
    "encoding/base64"
    "encoding/gob"
    "golang.org/x/oauth2/google"
    "golang.org/x/oauth2"
    calendar "google.golang.org/api/calendar/v3"
    "github.com/gorilla/sessions"
)
var conf oauth2.Config

func init() {
    gob.Register(&oauth2.Token{})
}

func getLoginURL(state string) string {
    // State can be some kind of random generated hash string.
    // See relevant RFC: http://tools.ietf.org/html/rfc6749#section-10.12
    return conf.AuthCodeURL(state)
}

func randToken() string {
    b := make([]byte, 32) 
    rand.Read(b)
    return base64.StdEncoding.EncodeToString(b)
}

func Login(w http.ResponseWriter, r *http.Request) {
    conf = &oauth2.Config{
        ClientID: "your-client-id",
        ClientSecret: "your-client-secret",
        RedirectUrl: "https://www.yoursite.com/auth",
        Endpoint: google.Endpoint,
        Scopes: []string{"https://www.googleapis.com/auth/calendar"}
    }
    state := randToken()
    sess, _ := session.Get(r, "session")
    sess.Values["state"] = state
    sess.Save(r, w)
    http.Redirect(w, r, conf.AuthCodeURL(state), http.StatusFound)
}

func Auth(w http.ResponseWriter, r *http.Request) {
    sess, _ := session.Get(r, "session")
    state = sess.Values["state"]
    if state != r.URL.Query().Get("state") {
        http.Error(w, "authorization failed", http.StatusUnauthorized)
        return
    }
    tok, _ := conf.Exchange(oauth2.NoContext, c.QueryParam("code"))
    sess.Values["token"] = tok 
    sess.Save(r, w)
    http.Redirect(w, r, "https://www.yoursite.com/profile", http.StatusFound)
}

func GetClient(r *http.Request) *http.Client {
    sess, _ := session.Get(r, "session")
    tok, _ := sess.Values["token"].(*oauth2.Token)
    client := conf.Client(oauth2.NoContext, tok)
    return client
}

func Calendar(w http.ResponseWriter, r *http.Request) {
    client := GetClient(r)
    calendarService, _ = calendar.New(client)
    //do stuff
}

So, you send them to your Login handler, this generates a random key, and sends it (and the user) to google to have them login and authorize you to access their calendars, which will then redirect them to you Auth handler. This will make sure that the state key they sent back matches the one you sent, and if so, will get the token from Google. You then save it to the session. When you want to get their client, you fetch the token from your session, and use it to exchange for a new Client, which you then use to create your Calendar service.

I haven't checked the code exactly, but I tried to make a minimal example from my app which actually uses basically this code, so it should work (aside from probably missing an import or typos or some really minor stuff).