How to modify event on Google Calendar API with server - php

Question

I got oauth2 working - when a user logs into my application, they have to log into their Google account. Then they can make manually sync all events from my website's calendar to their Google Calendar.
BUT, how can I make it so that my server will be able to modify their Google Calendar (add, edit, delete) events without them actually being present at the computer? Because right now, it uses $_SESSION to check if the user is logged into their Google account.
For example, here is how to insert/add an event via API into Google Calendar:
$client = new Google_Client();
$client->setAuthConfig('client_secrets.json');
$client->addScope(Google_Service_Calendar::CALENDAR);
$client->setAccessType("offline");
$service = new Google_Service_Calendar($client);
if (isset($_SESSION['access_token']) && $_SESSION['access_token']) {
$event = new Google_Service_Calendar_Event(array(
'summary' => 'Google I/O 2015',
'location' => '800 Howard St., San Francisco, CA 94103',
'description' => 'A chance to hear more about Google\'s developer products.',
'start' => array(
'dateTime' => '2015-05-28T09:00:00-07:00',
'timeZone' => 'America/Los_Angeles',
),
'end' => array(
'dateTime' => '2015-05-28T17:00:00-07:00',
'timeZone' => 'America/Los_Angeles',
),
));
$event = $service->events->insert('primary', $event);
} else {
$redirect_uri = '/oauth.php';
header('Location: ' . filter_var($redirect_uri, FILTER_SANITIZE_URL));
exit();
}
But as you can see, that requires an access_token which is stored in $_SESSION, and if there is no access token, then it will redirect them to login into their Google Account.
How can my server access their Google Calendar account in the background and add/edit/remove events?

Answer 1

You must create "application" in console.developers.google.com and create "authorization credentials" for it.
You will get a json file which you need to use for auth
Read here for more detail https://developers.google.com/api-client-library/php/auth/web-app#creatingcred
You can use this https://github.com/googleapis/google-api-php-client
So edit will look like
include_once 'google.api.php';
$eventId = '010101010101010101010101';
$calendarID='xyxyxyxyxyxyxyxyxy#group.calendar.google.com';
// Get Event for edit
$event = $service->events->get($calendarID, $eventId);
$event->setSummary('New title');
$event->setDescription('New describtion');
$event->setStart(
new Google_Service_Calendar_EventDateTime(['dateTime' => date("c", strtotime("2018-09-20 09:40:00")),'timeZone' => 'Europe/Moscow'])
);
$event->setEnd(
new Google_Service_Calendar_EventDateTime(['dateTime' => date("c", strtotime("2018-09-20 10:40:00")),'timeZone' => 'Europe/Moscow'])
);
$updatedEvent = $service->events->update($calendarID, $eventId, $event);
Where google.api.php will be something like this
require_once __DIR__ .'/vendor/autoload.php';
function getClient()
{
$client = new Google_Client();
$client->setApplicationName('Google Calendar API PHP Quickstart');
$client->setScopes(Google_Service_Calendar::CALENDAR);
$client->setAuthConfig('credentials.json');
$client->setAccessType('offline');
// Load previously authorized credentials from a file.
$credentialsPath = 'token.json';
if (file_exists($credentialsPath)) {
$accessToken = json_decode(file_get_contents($credentialsPath), true);
} else {
// Request authorization from the user.
$authUrl = $client->createAuthUrl();
printf("Open the following link in your browser:\n%s\n", $authUrl);
print 'Enter verification code: ';
$authCode = trim(fgets(STDIN));
// Exchange authorization code for an access token.
$accessToken = $client->fetchAccessTokenWithAuthCode($authCode);
// Store the credentials to disk.
if (!file_exists(dirname($credentialsPath))) {
mkdir(dirname($credentialsPath), 0700, true);
}
file_put_contents($credentialsPath, json_encode($accessToken));
printf("Credentials saved to %s\n", $credentialsPath);
}
$client->setAccessToken($accessToken);
// Refresh the token if it's expired.
if ($client->isAccessTokenExpired()) {
$client->fetchAccessTokenWithRefreshToken($client->getRefreshToken());
file_put_contents($credentialsPath, json_encode($client->getAccessToken()));
}
return $client;
}
// Get the API client and construct the service object.
$client = getClient();
$service = new Google_Service_Calendar($client);
// Print the next 10 events on the user's calendar.
$calendarId = 'primary';
$optParams = array(
'maxResults' => 10,
'orderBy' => 'startTime',
'singleEvents' => true,
'timeMin' => date('c'),
);
$results = $service->events->listEvents($calendarId, $optParams);
if (empty($results->getItems())) {
print "No upcoming events found.\n";
} else {
print "Upcoming events:\n";
foreach ($results->getItems() as $event) {
$start = $event->start->dateTime;
if (empty($start)) {
$start = $event->start->date;
}
printf("%s (%s)\n", $event->getSummary(), $start);
}
}