Upload file to Google Drive programmatically

Nowadays I am writing a WordPress plugin that involves accessing and upload file to google drive programmatically. This process implies the following steps:

• request an authorization code from the Google Authorization Server

• get the authorization code and then use it to send a POST request in order to obtain an access token from the Google Authorization Server

• use the access token and upload the file

The authorization sequence looks like this:

  Of course, you can do all of these much simple by using the Google Client Library but I don't like this approach because it implies an external dependency and perhaps a complex chain of classes that are not really necessary (just convince yourself by reading my PHP example below). Below you can find a simplified approach of the above idea. It is a PHP code that encompasses the following blocks:

• a function that launches the authentication process

  • a function that requests the authorization code

  • a function that requests the access token

  • a function that stores and/or load the access token to/from a local file

• a function that returns either the access token or, in case it is expired, the refresh token

• a function that uploads a file to the Google Drive associated to that access token

<!--?php $GAPIS = 'https://www.googleapis.com/'; $GAPIS_AUTH = $GAPIS . 'auth/'; $GOAUTH = 'https://accounts.google.com/o/oauth2/'; $CLIENT_ID = 'my-google-client_id'; $CLIENT_SECRET = 'my-google-client_secret'; $REDIRECT_URI = 'http' . ($_SERVER['SERVER_PORT'] == 80 ? '' : 's') . '://' . $_SERVER['SERVER_NAME'] . $_SERVER['SCRIPT_NAME']; $SCOPES = array($GAPIS_AUTH . 'drive', $GAPIS_AUTH . 'drive.file', $GAPIS_AUTH . 'userinfo.email', $GAPIS_AUTH . 'userinfo.profile'); $STORE_PATH = 'credentials.json'; function uploadFile($credentials, $filename, $targetPath) { global $GAPIS; $ch = curl_init(); curl_setopt($ch, CURLOPT_URL, $GAPIS . 'upload/drive/v2/files?uploadType=media'); curl_setopt($ch, CURLOPT_BINARYTRANSFER, 1); curl_setopt($ch, CURLOPT_POSTFIELDS, file_get_contents($filename)); curl_setopt($ch, CURLOPT_POST, 1); curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); curl_setopt($ch, CURLOPT_HTTPHEADER, array('Content-Type : text/plain', 'Content-Length:' . filesize($filename), 'Authorization: Bearer ' . getAccessToken($credentials)) ); $postResult = curl_exec($ch); curl_close($ch); return json_decode($postResult, true); } function getStoredCredentials($path) { $credentials = json_decode(file_get_contents($path), true); if (isset($credentials['refresh_token'])) return $credentials; $expire_date = new DateTime(); $expire_date->setTimestamp($credentials['created']); $expire_date->add(new DateInterval('PT' . $credentials['expires_in'] . 'S')); $current_time = new DateTime(); if ($current_time->getTimestamp() >= $expire_date->getTimestamp()) { $credentials = null; unlink($path); } return $credentials; } function storeCredentials($path, $credentials) { $credentials['created'] = (new DateTime())->getTimestamp(); file_put_contents($path, json_encode($credentials)); return $credentials; } function requestAuthCode() { global $GOAUTH, $CLIENT_ID, $REDIRECT_URI, $SCOPES; $url = sprintf($GOAUTH . 'auth?scope=%s&redirect_uri=%s&response_type=code&client_id=%s&approval_prompt=force&access_type=offline', urlencode(implode(' ', $SCOPES)), urlencode($REDIRECT_URI), urlencode($CLIENT_ID) ); header('Location:' . $url); } function requestAccessToken($access_code) { global $GOAUTH, $CLIENT_ID, $CLIENT_SECRET, $REDIRECT_URI; $url = $GOAUTH . 'token'; $post_fields = 'code=' . $access_code . '&client_id=' . urlencode($CLIENT_ID) . '&client_secret=' . urlencode($CLIENT_SECRET) . '&redirect_uri=' . urlencode($REDIRECT_URI) . '&grant_type=authorization_code'; $ch = curl_init(); curl_setopt($ch, CURLOPT_POSTFIELDS, $post_fields); curl_setopt($ch, CURLOPT_POST, true); curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); curl_setopt($ch, CURLOPT_URL, $url); $result = curl_exec($ch); curl_close($ch); return json_decode($result, true); } function getAccessToken($credentials) { $expire_date = new DateTime(); $expire_date->setTimestamp($credentials['created']); $expire_date->add(new DateInterval('PT' . $credentials['expires_in'] . 'S')); $current_time = new DateTime(); if ($current_time->getTimestamp() >= $expire_date->getTimestamp()) return $credentials['refresh_token']; else return $credentials['access_token']; } function authenticate() { global $STORE_PATH; if (file_exists($STORE_PATH)) $credentials = getStoredCredentials($STORE_PATH); else $credentials = null; if (!(isset($_GET['code']) || isset($credentials))) requestAuthCode(); if (!isset($credentials)) $credentials = requestAccessToken($_GET['code']); if (isset($credentials) && isset($credentials['access_token']) && !file_exists($STORE_PATH)) $credentials = storeCredentials($STORE_PATH, $credentials); return $credentials; } $credentials = authenticate(); $result = uploadFile($credentials, 'my_file.txt', ''); if (!isset($result['id'])) throw new Exception(print_r($result)); else echo 'File copied successfuly (file Id: ' . $result['id'] . ')'; ?-->

• Read more about Google Drive Web APIs here.

• Read more about Authorizing Your App with Google Drive here.

• Read more about Using OAuth 2.0 to Access Google APIs here.

• Read more about API for Upload Files to Google Drive here.