Google OAuth API to get user's email address?

Question

I am playing with Google\'s OAuth 2.0 Playground using my own personal Google account, but I cannot seem to recover my Gmail address using the playground.

The scope

Answer 1

I have been following Prisoner's answer right above, and it helped me... until I received the email from Google Developers about how Google+ API will be shutdown on March 7, 2019.

I scrounged around and found this solution to get the email using an id_token that is returned when you authorize an app with the email scope on your developer console.

From Google Sign-in for Websites:

To validate an ID token in PHP, use the Google API Client Library for PHP. Install the library (for example, using Composer):

composer require google/apiclient

Then, call the verifyIdToken() function. For example:

require_once 'vendor/autoload.php';

// Get $id_token via HTTPS POST.

$client = new Google_Client(['client_id' => $CLIENT_ID]);  // Specify the CLIENT_ID of the app that accesses the backend
$payload = $client->verifyIdToken($id_token);
if ($payload) {
  $userid = $payload['sub'];
  // If request specified a G Suite domain:
  //$domain = $payload['hd'];
} else {
  // Invalid ID token
}

This will return an array that contains the user information, that also contains the email of the user who logged in. Hope this helps anyone else.