Google Cloud Endpoints - Switch user / Require sign in again

Question

When you authenticate with Google Cloud Endpoints if there is several Google Accounts signed in,that have already given your app permission, it simply chooses the default account, just like Gmail would do.

1) Gmail has the ability to switch Google Accounts in the top right corner. How would I achieve something similar?

2) Can you require a user to sign into their Google account again even if they are already signed in? Similar to when a user goes to change their account settings.

Answer 1

I've found a way, but it is a bit sad that this feature is not included (or not documented) in gapi.auth.authorize.

Anyway, if you open the authorization popup manually, and then process the resulting token, you can pass additional parameters such as prompt=select_account, which will allow the user to select their account.

Here's a code example. With popup blocking, you will have to call this function in an onclick event for the popup not to be blocked.

As such, the code is not really production-ready. We do not manage cases such as when the user refuses to give his consent, and we do not pass extra token information such as the expiration time.

var switchUserAccount = function (callback) {
        var popup = window.open("https://accounts.google.com/o/oauth2/auth?client_id=102862643449-geb89aoann7dj6tsha4mtkhvos5mk01b.apps.googleusercontent.com"
                + "&prompt=select_account"
                + "&scope=https://www.googleapis.com/auth/userinfo.email"
                + "&redirect_uri=https://david-sandbox.appspot.com/autoclose.html"
                + "&access_type=online&response_type=token", "thewindow");

        var waitForPopup = function () {
            try {
                var token = popup.location.hash.substring(14).split("&")[0];
                console.log("FOund token !" + token);
                if (token == "") {
                    console.log("Not ready yet")
                    setTimeout(waitForPopup, 500);
                } else {
                    gapi.auth.setToken({access_token: token});
                    popup.close();
                    callback();
                }
            }
            catch (e) {
                console.log("Not ready yet, exception")
                setTimeout(waitForPopup, 500);
            }
        };

        waitForPopup();
    }