Using Google+ API for PHP — Need to get the users email

The UserInfo API is now supported by the Google API PHP Client.

Here's a small sample application: http://code.google.com/p/google-api-php-client/source/browse/trunk/examples/userinfo/index.php

The important bit of the sample is here:

  $client = new apiClient();
  $client->setApplicationName(APP_NAME);
  $client->setClientId(CLIENT_ID);
  $client->setClientSecret(CLIENT_SECRET);
  $client->setRedirectUri(REDIRECT_URI);
  $client->setDeveloperKey(DEVELOPER_KEY);
  $client->setScopes(array('https://www.googleapis.com/auth/userinfo.email',
        'https://www.googleapis.com/auth/plus.me'));      // Important!

  $oauth2 = new apiOauth2Service($client);

  // Authenticate the user, $_GET['code'] is used internally:
  $client->authenticate();

  // Will get id (number), email (string) and verified_email (boolean):
  $user = $oauth2->userinfo->get();
  $email = filter_var($user['email'], FILTER_SANITIZE_EMAIL);
  print $email;

I'm assuming this snippet was called with a GET request including the authorization code. Remember to include or require apiOauth2Service.php in order for this to work. In my case is something like this:

  require_once 'google-api-php-client/apiClient.php';
  require_once 'google-api-php-client/contrib/apiOauth2Service.php';

Good luck.

Forgive me if I'm missing something, but how do you know what Google account to link them with if you don't have their email address? Usually, you'd prompt the user to enter their Google Account's email in order to find their profile in the first place.

Using OAuth2, you can request permissions through the scope parameter. (Documentation.) I imagine the scopes you want are https://www.googleapis.com/auth/userinfo.email and https://www.googleapis.com/auth/userinfo.profile.

Then, it's a simple matter to get the profile info once you've obtained your access token. (I assume you've been able to redeem the returned authorization code for an access token?) Just make a get request to https://www.googleapis.com/oauth2/v1/userinfo?access_token={accessToken}, which returns a JSON array of profile data, including email:

{
 "id": "00000000000000",
 "email": "[email protected]",
 "verified_email": true,
 "name": "Fred Example",
 "given_name": "Fred",
 "family_name": "Example",
 "picture": "https://lh5.googleusercontent.com/-2Sv-4bBMLLA/AAAAAAAAAAI/AAAAAAAAABo/bEG4kI2mG0I/photo.jpg",
 "gender": "male",
 "locale": "en-US"
}

There's got to be a method in the PHP library to make that request, but I can't find it. No guarantees, but try this:

$url = "https://www.googleapis.com/oauth2/v1/userinfo";
$request = apiClient::$io->makeRequest($client->sign(new apiHttpRequest($url, 'GET')));

if ((int)$request->getResponseHttpCode() == 200) {
        $response = $request->getResponseBody();
        $decodedResponse = json_decode($response, true);
        //process user info
      } else {
        $response = $request->getResponseBody();
        $decodedResponse = json_decode($response, true);
        if ($decodedResponse != $response && $decodedResponse != null && $decodedResponse['error']) {
          $response = $decodedResponse['error'];
        }
      }
 }

Anyway, in the code you posted, just pass the desired scope to createAuthUrl():

else {
    $authUrl = $client->createAuthUrl("https://www.googleapis.com/auth/userinfo.email https://www.googleapis.com/auth/userinfo.profile");
    print "<a class='login' href='$authUrl'>Connect Me!</a>";
}

Updated with today's API:

$googlePlus = new Google_Service_Plus($client);
$userProfile = $googlePlus->people->get('me');
$emails = $userProfile->getEmails();

This assumes the following:

1. You've authenticated the current user with the proper scopes.
2. You've set up $client with your client_id and client_secret.