Java

import com.google.gdata.client.*;
import com.google.gdata.client.calendar.*;

CalendarService client = new CalendarService("yourCompany-yourAppName-v1");
client.setUserCredentials("user@example.com", "pa$$word");

If you know your users will be using a G Suite account (as opposed to a Google/Gmail Account), you can streamline the login process by specifying the appropriate ClientLogin account type:

import com.google.gdata.client.*;
import com.google.gdata.client.calendar.*;

CalendarService client = new CalendarService("yourCompany-yourAppName-v1");
client.setUserCredentials("user@example.com", "pa$$word", ClientLoginAccountType.HOSTED);

.NET

using Google.GData.Client;
using Google.GData.Calendar;

CalendarService client = new CalendarService("yourCompany-yourAppName-v1");
client.setUserCredentials("user@example.com", "pa$$word");
client.QueryAuthenticationToken(); // Authenticate the user immediately

If you know your users will be using a G Suite account (as opposed to a Google/Gmail Account), you can streamline the login process by specifying the appropriate ClientLogin account type:

using Google.GData.Client;
using Google.GData.Calendar;

GDataGAuthRequestFactory authFactory = new GDataGAuthRequestFactory("cl", "yourCompany-yourAppName-v1");
authFactory.AccountType = "HOSTED";

CalendarService client = new CalendarService(authFactory.ApplicationName);
client.RequestFactory = authFactory;
client.setUserCredentials("user@example.com", "pa$$word");
client.QueryAuthenticationToken(); // Authenticate the user immediately

PHP

require_once 'Zend/Loader.php';
Zend_Loader::loadClass('Zend_Gdata_ClientLogin');
Zend_Loader::loadClass('Zend_Gdata_Calendar');

$serviceName = Zend_Gdata_Calendar::AUTH_SERVICE_NAME; // predefined service name ('cl') for calendar
$applicationName = 'yourCompany-yourAppName-v1';

// Create an authenticated HTTP client
$httpClient = Zend_Gdata_ClientLogin::getHttpClient('user@example.com', 'pa$$word', $serviceName, null, $applicationName);
$client = new Zend_Gdata_Calendar($httpClient, $applicationName); // Create an instance of the Calendar service

If you know your users will be using a G Suite account (as opposed to a Google/Gmail Account), you can streamline the login process by specifying the appropriate ClientLogin account type:

require_once 'Zend/Loader.php';
Zend_Loader::loadClass('Zend_Gdata_ClientLogin');
Zend_Loader::loadClass('Zend_Gdata_Calendar');

$serviceName = Zend_Gdata_Calendar::AUTH_SERVICE_NAME;
$applicationName = 'yourCompany-yourAppName-v1';
$accountType = 'HOSTED';

$httpClient = Zend_Gdata_ClientLogin::getHttpClient(
    'user@example.com', 'pa$$word', $serviceName, null, $applicationName, null, null, null, $accountType);
$client = new Zend_Gdata_Calendar($httpClient, $applicationName);

Python

If you're using the newer v2.0+ classes based off of GDClient, use:

import gdata.calendar.client

email = 'user@example.com'
password = 'pa$$word'
application_name = 'yourCompany-yourAppName-v1'

client = gdata.calendar.client.CalendarClient()
auth_token = client.ClientLogin(email, password,
                                application_name,
                                service='cl')

If you know your users will be using a G Suite account (as opposed to a Google/Gmail Account), you can streamline the login process by specifying the appropriate ClientLogin account type:

auth_token = client.ClientLogin(email, password,
                                application_name,
                                account_type='HOSTED',
                                service='cl')

Alternatively, if you're using the older v1.0 classes based off of GDataService, the calls are a bit different:

import gdata.calendar.service

email = 'user@example.com'
password = 'pa$$word'
application_name = 'yourCompany-yourAppName-v1'

client = gdata.calendar.service.CalendarService()
client.ClientLogin(email, password, source=application_name)

# OR, you can use ProgrammaticLogin()

client = gdata.calendar.service.CalendarService(email=email, password=password, source=application_name)
client.ProgrammaticLogin()

As in v2.0+, if your users will be using a G Suite account you can specify the appropriate ClientLogin account type:

import gdata.calendar.service

client = gdata.calendar.service.CalendarService()
client.ClientLogin('user@example.com', 'pa$$word', account_type='HOSTED', source='yourCompany-yourAppName-v1')

Java

String token = '12345abcde'; // TODO: Read user's token from your database
client.setUserToken(token);

UserToken auth_token = (UserToken) client.getAuthTokenFactory().getAuthToken();
token = auth_token.getValue(); // token is '12345abcde'

.NET

String token = '12345abcde'; // TODO: Read user's token from your database
client.SetAuthenticationToken(token);

GDataGAuthRequestFactory requestFactory = (GDataGAuthRequestFactory) client.RequestFactory;
token = requestFactory.GAuthToken;  // token is '12345abcde'

PHP

$token = '12345abcde'; // TODO: Read user's token from your database
$client->getHttpClient()->setClientLoginToken($token);

$token = $client->getHttpClient()->getClientLoginToken(); // $token is '12345abcde'

Python

If you're using the newer v2.0+ classes based off of GDClient, use:

import gdata.gauth

token = '12345abcde'  # TODO: Read user's token from your database
client.auth_token = gdata.gauth.ClientLoginToken(token)

token = client.auth_token.token_string  # token is '12345abcde'

If you're using the older v1.0 classes based off of GDataService, the process is a bit different.

token = '12345abcde'  # TODO: Read user's token from your database
client.SetClientLoginToken(token)

token = client.GetClientLoginToken()  # token is '12345abcde'

Java

String email = "user@example.com";
String password = "pa$$word";

try {
  client.setUserCredentials(email, password);
} catch (CaptchaRequiredException e) {
  System.out.println("Please visit " + e.getCaptchaUrl());
  System.out.print("Answer to the challenge? ");
  BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
  String answer = in.readLine();
  service.setUserCredentials(email, password, e.getCaptchaToken(), answer);

} catch (AuthenticationException e) {
  System.out.println(e.getMessage());
}

.NET

try
{
  client.setUserCredentials("user@example.com", "pa$$word");
  client.QueryAuthenticationToken(); // Authenticate the user immediately
}
catch (CaptchaRequiredException e)
{
  Console.WriteLine("Please visit " + e.Url);
  Console.Write("Answer to the challenge? ");
  String answer = Console.ReadLine();
  GDataGAuthRequestFactory requestFactory = (GDataGAuthRequestFactory) client.RequestFactory;
  requestFactory.CaptchaAnswer = answer;
  requestFactory.CaptchaToken = e.Token;
  client.QueryAuthenticationToken(); // authenticate the user again
}
catch (InvalidCredentialsException e)
{
  Console.WriteLine(e.Message);
}
catch (AuthenticationException e)
{
  Console.WriteLine(e.Message);
}

PHP

$email = 'user@example.com';
$password = 'pa$$word';
$serviceName = 'cl';  // 'cl' is the service name for the Calendar API
$appName = 'yourCompany-yourAppName-v1';

try {
  $httpClient = Zend_Gdata_ClientLogin::getHttpClient($email, $password, $serviceName, null, $appName);
} catch (Zend_Gdata_App_CaptchaRequiredException $e) {
  echo '<a href="' . $e->getCaptchaUrl() . '">CAPTCHA answer required to login</a>';
  $answer = 'Your answer to the challenge';
  $httpClient = Zend_Gdata_ClientLogin::getHttpClient(
      $email, $password, $serviceName, null, $appName, $e->getCaptchaToken(), $answer);

} catch (Zend_Gdata_App_AuthException $e) {
  echo 'Error: ' . $e->getMessage();
  if ($e->getResponse() != null) {
    echo 'Body: ' . $e->getResponse()->getBody();
  }
}

Python

If you're using the newer v2.0+ classes based off of GDClient, use:

import gdata.client

try:
  client.ClientLogin(email, password, application_name,
                     service='cl')
except gdata.client.CaptchaChallenge as challenge:
  print 'Please visit ' + challenge.captcha_url
  answer = raw_input('Answer to the challenge? ')
  client.ClientLogin(email, password, application_name,
                     captcha_token=challenge.captcha_token,
                     captcha_response=answer)
except gdata.client.BadAuthentication:
  exit('Users credentials were unrecognized')
except gdata.client.RequestError:
  exit('Login Error')

If you're using the older v1.0 classes based off of GDataService, the process is a bit different.

import gdata.service

email = 'user@example.com'
password = 'pa$$word'
application_name = 'yourCompany-yourAppName-v1'

try:
  client.ClientLogin(email, password, source=application_name)
except gdata.service.CaptchaRequired:
  print 'Please visit ' + client.captcha_url
  answer = raw_input('Answer to the challenge? ')
  client.ClientLogin(email, password, source=application_name,
                     captcha_token=client.captcha_token,
                     captcha_response=answer)
except gdata.service.BadAuthentication:
  exit('Users credentials were unrecognized')
except gdata.service.Error:
  exit('Login Error')