Not receiving refresh token auth 2.0 - php

Question

Hello I am newbie and using this library
php auth 2.0
which seems to be a good solution for using auth 2.0. I am trying to generate refresh token I can receive it. Here is my code:
OAuth2\Autoloader::register();
// $dsn is the Data Source Name for your database, for exmaple "mysql:dbname=my_oauth2_db;host=localhost"
$storage = new OAuth2\Storage\Pdo(array('dsn' => $this->dsn, 'username' => $this->username, 'password' => $this->password));
// Pass a storage object or array of storage objects to the OAuth2 server class
$server = new OAuth2\Server($storage,array('always_issue_new_refresh_token' => true,
'refresh_token_lifetime' => 2419200,));
// Add the "Client Credentials" grant type (it is the simplest of the grant types)
$server->addGrantType(new OAuth2\GrantType\ClientCredentials($storage));
$server->addGrantType(new OAuth2\GrantType\RefreshToken($storage));
Here is request:
$curl = curl_init();
curl_setopt($curl, CURLOPT_URL,"http://localhost/eventapp/index.php/oauth/handle");
curl_setopt($curl, CURLOPT_POST, 1);
curl_setopt($curl, CURLOPT_POSTFIELDS, "grant_type=client_credentials&client_id=ID&client_secret=SECRET");
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
$result=curl_exec($curl);
curl_close ($curl);
$result=get_object_vars(json_decode($result));
print_r($result);
Can anyone help me with this? Please guide me what I am doing wrong here?

Answer 1

$grantType = new OAuth2\GrantType\RefreshToken($storage, array(
'always_issue_new_refresh_token' => true
));
The Refresh Token grant type has the following configuration:
always_issue_new_refresh_token
whether to issue a new refresh token upon successful token request
Default: false
So by default its false,you have make it true.
Also check here
Example Request
$ curl -u TestClient:TestSecret https://api.mysite.com/token -d 'grant_type=password&username=bshaffer&password=brent123'
The access token will then contain a refresh token
{
"access_token":"2YotnFZFEjr1zCsicMWpAA",
"expires_in":3600,
"token_type": "bearer",
"scope":null,
"refresh_token":"tGzv3JOkF0XG5Qx2TlKWIA",
}