Google Drive API - Fetch Shared Files Download Links - php

Question

I am new to Google Drive and have uploaded many files. I have changed the status of all files to be shared if the download link is known.
I would like to use PHP to generate a list of all of the direct download links for the files. The PHP script is run on my localhost and I just need the array to be saved to a text file to be used later.
I have had a very hard time trying to get Oauth working but came across this script that looks like what I need. I set up my service account and have my service account email and .p12 file.
I downloaded the Google PHP client code base and set up a test script on my localhost. This is what I have
require_once "Google/Client.php";
require_once "Google/Service/Drive.php";
require_once "Google/Service/Oauth2.php";
require_once "Google/Auth/AssertionCredentials.php";
session_start();
function buildService($userEmail) {
$SERVICE_ACCOUNT_EMAIL = '12345#developer.gserviceaccount.com';
$SERVICE_ACCOUNT_PKCS12_FILE_PATH = '12345-privatekey.p12';
$key = file_get_contents($SERVICE_ACCOUNT_PKCS12_FILE_PATH);
$auth = new Google_AssertionCredentials(
$SERVICE_ACCOUNT_EMAIL,
array('https://www.googleapis.com/auth/drive'),
$key);
$auth->sub = $userEmail;
$client = new Google_Client();
$client->setUseObjects(true);
$client->setAssertionCredentials($auth);
return new Google_DriveService($client);
}
//... function retrieveAllFiles($service)
$service = buildService("myemail#gmail.com");
$allFiles = retrieveAllFiles($service);
print_r($allFiles);
I am working off of this example
http://stackoverflow.com/questions/21046631/google-drive-api-php-cant-list-files
and this
https://developers.google.com/drive/web/delegation#instantiate_a_drive_service_object
I am unsure what to do, I have added the required libraries but the following functions are coming up as being unknown in the PHP script
Google_AssertionCredentials
setUseObjects
Google_DriveService
retrieveAllFiles
Am I missing an obvious library? They are named different in the example but I'm guessing the base names have changed since there were updates... I have spent a lot of time reading up on Google Drive and Oauth without any luck. My only goal with this script is to get a list of the direct download links. I can do it manually but there are too many files.
Any help would be great.
Thanks.
* EDIT: *
So I this is what I have tried to obtain my token:
I am following this quick start guide:
https://developers.google.com/drive/web/quickstart/quickstart-php
Here is my code
<?php
require_once 'Google/client.php';
require_once 'Google/Service/drive.php';
defined('STDIN') or define('STDIN', fopen('php://stdin', 'r')); //I had to add this part as I was getting an undefined error for STDIN
$client = new Google_Client();
// Get your credentials from the console
$client->setClientId('xxx.apps.googleusercontent.com');
$client->setClientSecret('xxx');
$client->setRedirectUri('http://localhost/test/fetch.php'); //same as registered one
$client->setScopes(array('https://www.googleapis.com/auth/drive'));
$service = new Google_Service_Drive($client);
$authUrl = $client->createAuthUrl();
//Request authorization
print "Please visit:\n$authUrl\n\n";
print "Please enter the auth code:\n";
$authCode = trim(fgets(STDIN));
// Exchange authorization code for access token
$accessToken = $client->authenticate($authCode);
$client->setAccessToken($accessToken);
This results in error
Fatal error: Uncaught exception 'Google_Auth_Exception' with message 'Invalid code' in C:\Apache24\htdocs\test\Google\Auth\OAuth2.php:95 Stack trace: #0 C:\Apache24\htdocs\test\Google\Client.php(135): Google_Auth_OAuth2->authenticate('') #1 C:\Apache24\htdocs\test\new.php(26): Google_Client->authenticate('') #2 {main} thrown in C:\Apache24\htdocs\test\Google\Auth\OAuth2.php on line 95
Any thoughts ?
Thanks.
ANOTHER EDIT
So I have reverted to the old Drive PHP library as the new Drive PHP library has no documentation or examples.
This is my attempt to obtain a token and fetch the direct download file links
require_once 'google-old/google-api-php-client/src/Google_Client.php';
require_once 'google-old/google-api-php-client/src/contrib/Google_DriveService.php';
$client = new Google_Client();
// Get your credentials from the console
$client->setClientId('xx.apps.googleusercontent.com');
$client->setClientSecret('xx');
$client->setRedirectUri('urn:ietf:wg:oauth:2.0:oob');
$client->setScopes(array('https://www.googleapis.com/auth/drive'));
$service = new Google_DriveService($client);
$authUrl = $client->createAuthUrl();
//Request authorization
print "Please visit:\n$authUrl\n\n";
print "Please enter the auth code:\n";
$authCode = trim(fgets(STDIN));
// Exchange authorization code for access token
$accessToken = $client->authenticate($authCode);
$client->setAccessToken($accessToken);
$getAll = retrieveAllFiles($service);
print "<pre>";
print_r($getAll);
print "</pre>";
/**
* Retrieve a list of File resources.
*
* #param Google_DriveService $service Drive API service instance.
* #return Array List of Google_DriveFile resources.
*/
function retrieveAllFiles($service) {
$result = array();
$pageToken = NULL;
do {
try {
$parameters = array();
if ($pageToken) {
$parameters['pageToken'] = $pageToken;
}
$files = $service->files->listFiles($parameters);
$result = array_merge($result, $files->getItems());
$pageToken = $files->getNextPageToken();
} catch (Exception $e) {
print "An error occurred: " . $e->getMessage();
$pageToken = NULL;
}
} while ($pageToken);
return $result;
}
The problem I now face is that I am stuck at the "Paste the code into your app" part.
The
$authCode = trim(fgets(STDIN));
doesn't seem to want to execute.
Also I believe the file fetching code will just fetch the file names, and not the direct download links. I could not find an example for this.
Any suggestions would be much appreciated.
Thanks.
I am testing this on my localhost.

Answer 1

Firstly, separate your learning about OAuth from your learning about Drive. As a combined problem, it's hard, but as two separate problems, it's pretty simple.
For OAuth, everything you need to know is on this one web page https://developers.google.com/accounts/docs/OAuth2WebServer
Having read that page and understood it, if you want to use a library to make the calls, go ahead. IMHO the OAuth libraries don't do a great job, but ymmv. With or without a library, it is essential that you understand what is happening.
Having cracked OAuth, you end up with a shiny access_token which you drop into the Drive API, either as an http header if you are calling the rar API, or wrapped in a credential object if you are using one of the libraries.

Answer 2

Replace the STDIN stuff.
put this in instead:
if (!isset($_GET['code'])) {
print "Please visit:\n$authUrl\n\n";
print "Please enter the auth code:\n";
} else { $authCode = ''; }
//$authCode = trim(fgets(STDIN));
$authCode = $_GET['code'];
Google's code is buggy in terms of their thing. Having done so I'm getting file creation (it's still pumping out an error but it's producing the files).
replace their file_get_contents line with:
$data = 'blahblah blah';//file_get_contents('document.txt');
and there you go.