Getting 'Forbidden error' when trying to execute youtube analytic API - php

Question

I am receiving an error message when trying to execute youtube analytics API.
A service error occurred: Error calling GET
https://www.googleapis.com/youtube/analytics/v1/reports?ids=channel%3D%3DUCaayLD9i5x4MmIoVZxXSv_g&start-date=2016-08-01&end-date=2016-08-07&metrics=views&dimensions=7DayTotals:
(403) Forbidden
Here is my code:
require_once __DIR__.'\google-api-php-client-1-master\src\Google\autoload.php';
require_once __DIR__.'\google-api-php-client-1-master\src\Google\Client.php';
require_once __DIR__.'\google-api-php-client-1-master\src\Google\Service\YouTube.php';
session_start();
$key = file_get_contents('mykey.json');
$OAUTH2_CLIENT_ID = 'xx-xx-xx';
$OAUTH2_CLIENT_SECRET = 'xxx';
$scope = array("https://www.googleapis.com/auth/youtube.force-ssl", "https://www.googleapis.com/auth/youtubepartner-channel-audit", "https://www.googleapis.com/auth/youtube", "https://www.googleapis.com/auth/youtube.readonly", "https://www.googleapis.com/auth/yt-analytics.readonly", "https://www.googleapis.com/auth/yt-analytics-monetary.readonly","https://www.googleapis.com/auth/youtubepartner");
$client = new Google_Client();
$client->setClientId($OAUTH2_CLIENT_ID);
$client->setClientSecret($OAUTH2_CLIENT_SECRET);
$client->setAccessType('offline');
$client->setAccessToken($key);
$client->setScopes($scope);
if ($client->getAccessToken()) {
//Check to see if our access token has expired. If so, get a new one and save it to file for future use.
if($client->isAccessTokenExpired()) {
//refresh your access token if it's expired
$newToken = json_decode($client->getAccessToken());
$client->refreshToken($newToken->refresh_token);
file_put_contents('mykey.json', $client->getAccessToken());
}
$analytics = new Google_Service_YouTubeAnalytics($client);
$channel_url = 'UCaayLD9i5x4MmIoVZxXSv_g';
$ids = 'channel==' . $channel_url . '';
$end_date = '2016-08-07';
$start_date = '2016-08-01';
$optparams = array(
'dimensions' => '7DayTotals',
);
$metric = 'views';
$api = $analytics->reports->query($ids, $start_date, $end_date, $metric, $optparams);
echo '<pre>';print_r($api);die;
}
I have already enable 'youtube analytic API' and I get the access_token from here
What is wrong with my code ,Or do we need to do some more stuff to get rid from this?

Answer 1

Looking at your code, it seems that you are generating a new access token at the point you save it to file (invalidating the first one).
Try :
if($client->isAccessTokenExpired()) {
//refresh your access token if it's expired
$newToken = json_decode($client->getAccessToken());
$client->refreshToken($newToken->refresh_token);
file_put_contents('mykey.json', $newToken);
}