(Perl) Google Sheets Refresh an Expired Access Token

Demonstrates how to refresh an expired access token. If a Google Sheets REST API call results in a 401 "unauthorized" response, then it is likely the access token expired. An application should be able to automatically refresh the access token with no user interaction and then re-try the request with the newly obtained access token.

Chilkat Perl Downloads Perl Module for Windows, MacOS, Linux, Alpine Linux, Solaris

use chilkat();

#  This example requires the Chilkat API to have been previously unlocked.
#  See Global Unlock Sample for sample code.

#  It is assumed we previously obtained an OAuth2 access token.
#  This example loads the JSON access token file
#  saved by this example: Get Google Sheets OAuth2 Access Token

$jsonToken = chilkat::CkJsonObject->new();
$success = $jsonToken->LoadFile("qa_data/tokens/googleSheets.json");
if ($success != 1) {
    print "Failed to load googleSheets.json" . "\r\n";
    exit;
}

#  The access token JSON looks like this:

#  	{
#  	 "access_token": "abac.Ci-ZabcdF37-NUrmSzxbHxTsMbtlN-uPfabcdAQN_2ekzj0s5ofCzRabcdTDMGaa2Q",
#  	 "token_type": "Bearer",
#  	 "expires_in": 3600,
#  	 "refresh_token": "1/lEe5abcdNJ77eOSDBabcdkQGVmDalkwabcdR2Hatbo"
#  	}
# 

$oauth2 = chilkat::CkOAuth2->new();

$oauth2->put_TokenEndpoint("https://www.googleapis.com/oauth2/v4/token");

#  Replace these with actual values.
$oauth2->put_ClientId("GOOGLE-CLIENT-ID");
$oauth2->put_ClientSecret("GOOGLE-CLIENT-SECRET");

#  Get the "refresh_token"
$oauth2->put_RefreshToken($jsonToken->stringOf("refresh_token"));

#  Send the HTTP POST to refresh the access token..
$success = $oauth2->RefreshAccessToken();
if ($success != 1) {
    print $oauth2->lastErrorText() . "\r\n";
    exit;
}

#  The response contains a new access token, but we must keep
#  our existing refresh token for when we need to refresh again in the future.
$jsonToken->UpdateString("access_token",$oauth2->accessToken());

#  Save the new JSON access token response to a file.
$sbJson = chilkat::CkStringBuilder->new();
$jsonToken->put_EmitCompact(0);
$jsonToken->EmitSb($sbJson);
$sbJson->WriteFile("qa_data/tokens/googleSheets.json","utf-8",0);

print "OAuth2 authorization granted!" . "\r\n";
print "New Access Token = " . $oauth2->accessToken() . "\r\n";