OAuth 2.0 in php using curl

Question

I need to get my access_token and refresh_token for OAuth 2.0 to Access Google APIs, the php script below should return a json with access_token, refresh_token like this:

Answer 1

Wow, stupid mistake, I should have a rest.

The variables names don't match. I defined:

    $client_id = '###.apps.googleusercontent.com';
    $client_secret = '###';

But here I used an non-existing clientID and clientSecret :

    curl_setopt($ch, CURLOPT_POSTFIELDS, array(
    'code' => $code,
    'client_id' => $clientID,
    'client_secret' => $clientSecret,
    'redirect_uri' => $redirect_uri,
    'grant_type' => 'authorization_code'
    ));

Fixed and working PHP script

    $client_id = '###.apps.googleusercontent.com';
    $redirect_uri = 'http://localhost/phpConnectToDB/csv/refreshFusionTable.php';
    $client_secret = '###';

    $ch = curl_init();
    
    curl_setopt($ch, CURLOPT_URL, "https://accounts.google.com/o/oauth2/token");
    
    curl_setopt($ch, CURLOPT_POST, TRUE);
    
    $code = $_REQUEST['code'];

    // This option is set to TRUE so that the response
    // doesnot get printed and is stored directly in
    // the variable
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
    
    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
    
    curl_setopt($ch, CURLOPT_POSTFIELDS, array(
    'code' => $code,
    'client_id' => $client_id,
    'client_secret' => $client_secret,
    'redirect_uri' => $redirect_uri,
    'grant_type' => 'authorization_code'
    ));

    $data = curl_exec($ch);
    
    var_dump($data);

But I have to say that google provides a little misleading error message here, because I hadn't defined client_id nor client_secret and the error message was:

    {
    "error" : "invalid_request",
    "error_description" : "Client must specify either client_id or client_assertion, not both"
    }