Google Drive API v3 - downloading files in PHP
I'm trying to understand the download flow for the Google Drive API v3 using PHP. Using the API v2 to download a file I:
- Got the file metadata
- Used the downloadUrl parameter to get a direct link to the file, attached an oAuth token to it and made a GET request to that.
Using API v3 this appears to have been deprecated, and according to the docs you call files->get() on the Drive Service with an array parameter of "alt" => "media" to get the file itself rather than the metadata.
And their example was:
$fileId = '0BwwA4oUTeiV1UVNwOHItT0xfa2M';
$content = $driveService->files->get($fileId, array(
'alt' => 'media' ));
I'm having trouble understanding how this works though and have trawled through the code but it didn't give much more info.
When you call get(), what actually goes into $content in the example? Is it the contents of the file (in which case this seems troublesome when dealing with large files - surely you'll get out of memory?!) or is it some type of stream reference that I can call fopen on? How would I save this file to disk?
The documentation doesn't really go into any detail about what happens when you make that API call, it just says it performs a file download?
Answer
I figured it out after a bit of experimenting.
When you call the get() method with the alt=>media parameter as specified in the docs you get the underlying HTTP response which is a Guzzle response object (as apparently the client library uses Guzzle for it's underlying transport).
From there you can call any Guzzle response method such as $response->getStatusCode() or you can get a stream of the actual file content.
Would have been helpful if they had documented this somewhere!
EDIT: Here's a rough example if anyone else gets stuck of how to save a file.
<?php
date_default_timezone_set("Europe/London");
require_once 'vendor/autoload.php';
// I'm using a service account, use whatever Google auth flow for your type of account.
putenv('GOOGLE_APPLICATION_CREDENTIALS=/path/to/service/account/key.json');
$client = new Google_Client();
$client->addScope(Google_Service_Drive::DRIVE);
$client->useApplicationDefaultCredentials();
$service = new Google_Service_Drive($client);
$fileId = "0Bxxxxxxxxxxxxxxxxxxxx"; // Google File ID
$content = $service->files->get($fileId, array("alt" => "media"));
// Open file handle for output.
$outHandle = fopen("/path/to/destination", "w+");
// Until we have reached the EOF, read 1024 bytes at a time and write to the output file handle.
while (!$content->getBody()->eof()) {
fwrite($outHandle, $content->getBody()->read(1024));
}
// Close output file handle.
fclose($outHandle);
echo "Done.\n"
?>