Are you familiar with adding an event with authentication? Like i answered here.
And like in the code below. If you are... you can go to the next level ;)
(You can download the Google Api Php-client on this page. On this page there is a tutorial. It's for Google+ but the principle is the same)
The first time you would always need authentication. There is no way around that. In the example below you get a token back after authentication, which includes an access_token and a refresh_token. The access_token is only valid for 3600 seconds and is used for direct access. When the access_token is expired you get a 401 error and you can use the refresh_token (together with client_id, client_secret and the correct grant_type) to request a new access_token.
You can find some more information on this page (at the bottom "Using a Refresh Token"). There are some limits in numbers to request these, mentioned on that page at the bottom.
This is some testing code i made the last time i helped someone with this. It only shows getting the authentication and storing the token in a cookie. It does not request a new access_token after it expires.
But as i already said you need to store the token (in a database?) and when you get a 401 you need to request a new access_token with the client_id, client_secret, correct grant_type and refresh_token. There is no (re-)authentication necessary for that.
<?php
error_reporting(E_ALL);
require_once 'google-api-php-client/src/Google_Client.php';
require_once 'google-api-php-client/src/contrib/Google_CalendarService.php';
session_start();
if ((isset($_SESSION)) && (!empty($_SESSION))) {
echo "There are cookies<br>";
echo "<pre>";
print_r($_SESSION);
echo "</pre>";
}
$client = new Google_Client();
$client->setApplicationName("Google Calendar PHP Starter Application");
$client->setClientId('###');
$client->setClientSecret('###');
$client->setRedirectUri('http://###/add_calendar.php'); // <- registered web-page
//$client->setDeveloperKey('###'); // <- not always needed
$cal = new Google_CalendarService($client);
if (isset($_GET['logout'])) {
echo "<br><br><font size=+2>Logging out</font>";
unset($_SESSION['token']);
}
if (isset($_GET['code'])) {
echo "<br>I got a code from Google = ".$_GET['code']; // You won't see this if redirected later
$client->authenticate(); // $_GET['code']
$_SESSION['token'] = $client->getAccessToken();
header('Location: http://' . $_SERVER['HTTP_HOST'] . $_SERVER['PHP_SELF']);
// not strictly necessary to redirect but cleaner for the url in address-bar
echo "<br>I got the token = ".$_SESSION['token']; // <-- not needed to get here unless location uncommented
}
if (isset($_SESSION['token'])) {
echo "<br>Getting access";
$client->setAccessToken($_SESSION['token']);
}
if ($client->getAccessToken()){
echo "<hr><font size=+1>I have access to your calendar</font>";
$event = new Google_Event();
$event->setSummary('=== I ADDED THIS ===');
$event->setLocation('The Neighbourhood');
$start = new Google_EventDateTime();
$start->setDateTime('2013-11-29T10:00:00.000-05:00');
$event->setStart($start);
$end = new Google_EventDateTime();
$end->setDateTime('2013-11-29T10:25:00.000-05:00');
$event->setEnd($end);
$createdEvent = $cal->events->insert('###', $event); // <- ### = email of calendar
echo "<br><font size=+1>Event created</font>";
echo "<hr><br><font size=+1>Already connected</font> (No need to login)";
} else {
$authUrl = $client->createAuthUrl();
print "<hr><br><font size=+2><a href='$authUrl'>Connect Me!</a></font>";
}
$url = 'http://' . $_SERVER['HTTP_HOST'] . $_SERVER['PHP_SELF'];
echo "<br><br><font size=+2><a href=$url?logout>Logout</a></font>";
?>
Edit:
If you don't want the initial authentication Google has its "Service Acounts", as you pointed out.
(I didn't know about these :)
I dug up some links where you can find code to use after you got the key-file.
Edit Google calendar events from Google service account: 403
Access Google calendar events from with service account: { "error" : "access_denied" }. No google apps
Google OAuth 2.0 Service Account - Calendar API (PHP Client)
https://groups.google.com/forum/#!topic/google-api-php-client/B7KXVQvx1k8
https://groups.google.com/forum/?fromgroups#!topic/google-api-php-client/IiwRBKZMZxw
Edit #2: YES, got it working. (even with my free Google account ;)
Here is the working code:
<?
error_reporting(E_ALL);
require_once 'google-api-php-client/src/Google_Client.php';
require_once 'google-api-php-client/src/contrib/Google_CalendarService.php';
session_start();
echo "Busy<br>";
const CLIENT_ID = 'xxxxxxxxxx.apps.googleusercontent.com';
const SERVICE_ACCOUNT_NAME = 'xxxxxxxxxxx@developer.gserviceaccount.com';
const KEY_FILE = 'xxxxxxxxxxxxxxxxxxx-privatekey.p12';
const CALENDAR_NAME = 'xxxxxxx@gmail.com';
$client = new Google_Client();
$client->setApplicationName("mycal");
if (isset($_SESSION['token'])) {
$client->setAccessToken($_SESSION['token']);
}
$key = file_get_contents(KEY_FILE);
$client->setClientId(CLIENT_ID);
$client->setAssertionCredentials(new Google_AssertionCredentials(
SERVICE_ACCOUNT_NAME,
array('https://www.google.com/calendar/feeds/'),
$key)
);
$client->setClientId(CLIENT_ID);
$service = new Google_CalendarService($client);
$event = new Google_Event();
$event->setSummary('=== I MADE THIS ===');
$event->setLocation('Somewhere else');
$start = new Google_EventDateTime();
$start->setDateTime('2013-11-30T10:00:00.000-02:00');
$event->setStart($start);
$end = new Google_EventDateTime();
$end->setDateTime('2013-11-30T10:25:00.000-02:00');
$event->setEnd($end);
$createdEvent = $service->events->insert(CALENDAR_NAME, $event);
echo "Done<br>";
?>
I needed to make a "new project" on https://cloud.google.com/console#/project. I couldn't use the existing one. After activating "Calendar API" and registering a new Web-app with Certificate i only needed to share my calendar with the xxxx@developer.gserviceaccount.com and above code worked
(without authentication).
Edit #3: and now it also seems to be working in the default "Google+ API Project"
