(i) You have the wrong email in your

$client_id = '1303030303-wrongiddontuse7t9kdtai3l44jofnejr04.apps.googleusercontent.com'; //Client ID
 $service_account_name = '1303030303-wrongiddontuse7t9kdtai3l44jofnejr04@developer.gserviceaccount.com'; //Email Address 
$key_file_location = 'API Project-1234.p12'; //key.p12

Often people enter their own email address, but it must look like this weird cryptic string above. You can get your own ID on the developer's console page (assuming you paid and have an google for business account) :

https://console.developers.google.com/project/<yourProjectID>/apiui/credential

(2) You don't have enabled the specific scope which you are trying to access. For example in the examples/service-account.php sample provided, it tries to access the "Books API". In the screenshot below you see the three APIs enabled, you must have the one in your credential object :

$cred = new Google_Auth_AssertionCredentials( 
           $service_account_name, 
           array('https://www.googleapis.com/auth/books'), 
           $key );

This is what it should look like when you enable APIs

The post Error refreshing the OAuth2 token { “error” : “invalid_grant” } appeared first on Techy Things.

You first need to have your email on your domains managed by gmail: Google for Business.

That means you can already login in gmail on the web with yourname@yourdomain.com

The official documentation can be found there (please be signed in google with your account while accessing).

Basic documentation :

https://developers.google.com/gmail/api/

More documentation related specifically to have your app send mails on behalf of a user :

https://developers.google.com/appengine/docs/php/mail/

Overview

(i) Enable API for your a user
(2) Get the authentication key
(3) Download the client library to save on your server
(4) Write code

https://developers.google.com/gmail/api/

There are two ways to use the Gmail API, one is with a web-server and redirection to google authentication page to click a button to accept, then redirected back to your app with credentials, stored in php session. This is not the way I am looking for.

The second way is "offline" authentication as google labels it. It is with pre-shared authentication keys.

https://developers.google.com/api-client-library/php/guide/aaa_oauth2_service

The sample code provided by google in PHP is there: \google-api-php-client\examples\service-account.php

Write Code

set_include_path(get_include_path() . PATH_SEPARATOR . '/path/to/google-api-php-client/src');

(under development..)

Troubleshooting

Fix Error refreshing the OAuth2 token { “error” : “invalid_grant” }

The post Send email using Gmail API / Google Mail API in PHP appeared first on Techy Things.