ファイルの変更を追跡する必要がある Google ドライブ アプリの場合、changes コレクションを使用すると、ユーザーと共有された変更を含むすべてのファイル変更を効率的に検出できます。ファイルが変更されている場合、コレクションには各ファイルの現在の状態が提供されます。
開始ページのトークンを取得する
アカウントの現在の状態のページトークンをリクエストするには、changes.getStartPageToken を使用します。このトークンを保存し、changes.list の最初の呼び出しで使用します。
現在のページトークンを取得するには:
Java
drive/snippets/drive_v3/src/main/java/FetchStartPageToken.java
import com.google.api.client.googleapis.json.GoogleJsonResponseException;
import com.google.api.client.http.HttpRequestInitializer;
import com.google.api.client.http.javanet.NetHttpTransport;
import com.google.api.client.json.gson.GsonFactory;
import com.google.api.services.drive.Drive;
import com.google.api.services.drive.DriveScopes;
import com.google.api.services.drive.model.StartPageToken;
import com.google.auth.http.HttpCredentialsAdapter;
import com.google.auth.oauth2.GoogleCredentials;
import java.io.IOException;
import java.util.Arrays;
/* Class to demonstrate use-case of Drive's fetch start page token */
public class FetchStartPageToken {
/**
* Retrieve the start page token for the first time.
*
* @return Start page token as String.
* @throws IOException if file is not found
*/
public static String fetchStartPageToken() throws IOException {
/*Load pre-authorized user credentials from the environment.
TODO(developer) - See https://developers.google.com/identity for
guides on implementing OAuth2 for your application. */
GoogleCredentials credentials = GoogleCredentials.getApplicationDefault()
.createScoped(Arrays.asList(DriveScopes.DRIVE_FILE));
HttpRequestInitializer requestInitializer = new HttpCredentialsAdapter(
credentials);
// Build a new authorized API client service.
Drive service = new Drive.Builder(new NetHttpTransport(),
GsonFactory.getDefaultInstance(),
requestInitializer)
.setApplicationName("Drive samples")
.build();
try {
StartPageToken response = service.changes()
.getStartPageToken().execute();
System.out.println("Start token: " + response.getStartPageToken());
return response.getStartPageToken();
} catch (GoogleJsonResponseException e) {
// TODO(developer) - handle error appropriately
System.err.println("Unable to fetch start page token: " + e.getDetails());
throw e;
}
}
}
Python
drive/snippets/drive-v3/change_snippet/fetch_start_page_token.py
import google.auth
from googleapiclient.discovery import build
from googleapiclient.errors import HttpError
def fetch_start_page_token():
"""Retrieve page token for the current state of the account.
Returns & prints : start page token
Load pre-authorized user credentials from the environment.
TODO(developer) - See https://developers.google.com/identity
for guides on implementing OAuth2 for the application.
"""
creds, _ = google.auth.default()
try:
# create drive api client
service = build("drive", "v3", credentials=creds)
# pylint: disable=maybe-no-member
response = service.changes().getStartPageToken().execute()
print(f'Start token: {response.get("startPageToken")}')
except HttpError as error:
print(f"An error occurred: {error}")
response = None
return response.get("startPageToken")
if __name__ == "__main__":
fetch_start_page_token()
PHP
drive/snippets/drive_v3/src/DriveFetchStartPageToken.php
use Google\Client;
use Google\Service\Drive;
# TODO - PHP client currently chokes on fetching start page token
function fetchStartPageToken()
{
try {
$client = new Client();
$client->useApplicationDefaultCredentials();
$client->addScope(Drive::DRIVE);
$driveService = new Drive($client);
$response = $driveService->changes->getStartPageToken();
printf("Start token: %s\n", $response->startPageToken);
return $response->startPageToken;
} catch(Exception $e) {
echo "Error Message: ".$e;
}
}
.NET
drive/snippets/drive_v3/DriveV3Snippets/FetchStartPageToken.cs
using Google.Apis.Auth.OAuth2;
using Google.Apis.Drive.v3;
using Google.Apis.Services;
namespace DriveV3Snippets
{
// Class to demonstrate use-case of Drive's fetch start page token
public class FetchStartPageToken
{
/// <summary>
/// Retrieve the starting page token.
/// </summary>
/// <returns>start page token as String, null otherwise.</returns>
public static string DriveFetchStartPageToken()
{
try
{
/* Load pre-authorized user credentials from the environment.
TODO(developer) - See https://developers.google.com/identity for
guides on implementing OAuth2 for your application. */
GoogleCredential credential = GoogleCredential.GetApplicationDefault()
.CreateScoped(DriveService.Scope.Drive);
// Create Drive API service.
var service = new DriveService(new BaseClientService.Initializer
{
HttpClientInitializer = credential,
ApplicationName = "Drive API Snippets"
});
var response = service.Changes.GetStartPageToken().Execute();
// Prints the token value.
Console.WriteLine("Start token: " + response.StartPageTokenValue);
return response.StartPageTokenValue;
}
catch (Exception e)
{
// TODO(developer) - handle error appropriately
if (e is AggregateException)
{
Console.WriteLine("Credential Not found");
}
else
{
throw;
}
}
return null;
}
}
}
Node.js
drive/snippets/drive_v3/change_snippets/fetch_start_page_token.js
/**
* Retrieve page token for the current state of the account.
**/
async function fetchStartPageToken() {
// Get credentials and build service
// TODO (developer) - Use appropriate auth mechanism for your app
const {GoogleAuth} = require('google-auth-library');
const {google} = require('googleapis');
const auth = new GoogleAuth({
scopes: 'https://www.googleapis.com/auth/drive.appdata',
});
const service = google.drive({version: 'v3', auth});
try {
const res = await service.changes.getStartPageToken({});
const token = res.data.startPageToken;
console.log('start token: ', token);
return token;
} catch (err) {
// TODO(developer) - Handle error
throw err;
}
}
変更を取得する
現在ログインしているユーザーの変更リストを取得するには、changes.list で説明されているように、changes コレクションに GET リクエストを送信します。
changes コレクション内のエントリは時系列で並べられます（最も古い変更が最初に表示されます）。includeRemoved クエリ パラメータと restrictToMyDrive クエリ パラメータは、削除されたアイテムと共有アイテムのどちらをレスポンスに含めるかを指定します。
Java
drive/snippets/drive_v3/src/main/java/FetchChanges.java
import com.google.api.client.googleapis.json.GoogleJsonResponseException;
import com.google.api.client.http.HttpRequestInitializer;
import com.google.api.client.http.javanet.NetHttpTransport;
import com.google.api.client.json.gson.GsonFactory;
import com.google.api.services.drive.Drive;
import com.google.api.services.drive.DriveScopes;
import com.google.api.services.drive.model.ChangeList;
import com.google.auth.http.HttpCredentialsAdapter;
import com.google.auth.oauth2.GoogleCredentials;
import java.io.IOException;
import java.util.Arrays;
/* Class to demonstrate use-case of Drive's fetch changes in file. */
public class FetchChanges {
/**
* Retrieve the list of changes for the currently authenticated user.
*
* @param savedStartPageToken Last saved start token for this user.
* @return Saved token after last page.
* @throws IOException if file is not found
*/
public static String fetchChanges(String savedStartPageToken) throws IOException {
/*Load pre-authorized user credentials from the environment.
TODO(developer) - See https://developers.google.com/identity for
guides on implementing OAuth2 for your application.*/
GoogleCredentials credentials = GoogleCredentials.getApplicationDefault()
.createScoped(Arrays.asList(DriveScopes.DRIVE_FILE));
HttpRequestInitializer requestInitializer = new HttpCredentialsAdapter(
credentials);
// Build a new authorized API client service.
Drive service = new Drive.Builder(new NetHttpTransport(),
GsonFactory.getDefaultInstance(),
requestInitializer)
.setApplicationName("Drive samples")
.build();
try {
// Begin with our last saved start token for this user or the
// current token from getStartPageToken()
String pageToken = savedStartPageToken;
while (pageToken != null) {
ChangeList changes = service.changes().list(pageToken)
.execute();
for (com.google.api.services.drive.model.Change change : changes.getChanges()) {
// Process change
System.out.println("Change found for file: " + change.getFileId());
}
if (changes.getNewStartPageToken() != null) {
// Last page, save this token for the next polling interval
savedStartPageToken = changes.getNewStartPageToken();
}
pageToken = changes.getNextPageToken();
}
return savedStartPageToken;
} catch (GoogleJsonResponseException e) {
// TODO(developer) - handle error appropriately
System.err.println("Unable to fetch changes: " + e.getDetails());
throw e;
}
}
}
Python
drive/snippets/drive-v3/change_snippet/fetch_changes.py
import google.auth
from googleapiclient.discovery import build
from googleapiclient.errors import HttpError
def fetch_changes(saved_start_page_token):
"""Retrieve the list of changes for the currently authenticated user.
prints changed file's ID
Args:
saved_start_page_token : StartPageToken for the current state of the
account.
Returns: saved start page token.
Load pre-authorized user credentials from the environment.
TODO(developer) - See https://developers.google.com/identity
for guides on implementing OAuth2 for the application.
"""
creds, _ = google.auth.default()
try:
# create drive api client
service = build("drive", "v3", credentials=creds)
# Begin with our last saved start token for this user or the
# current token from getStartPageToken()
page_token = saved_start_page_token
# pylint: disable=maybe-no-member
while page_token is not None:
response = (
service.changes().list(pageToken=page_token, spaces="drive").execute()
)
for change in response.get("changes"):
# Process change
print(f'Change found for file: {change.get("fileId")}')
if "newStartPageToken" in response:
# Last page, save this token for the next polling interval
saved_start_page_token = response.get("newStartPageToken")
page_token = response.get("nextPageToken")
except HttpError as error:
print(f"An error occurred: {error}")
saved_start_page_token = None
return saved_start_page_token
if __name__ == "__main__":
# saved_start_page_token is the token number
fetch_changes(saved_start_page_token=209)
PHP
drive/snippets/drive_v3/src/DriveFetchChanges.php
use Google\Client;
use Google\Service\Drive;
# TODO - PHP client currently chokes on fetching start page token
function fetchChanges()
{
try {
$client = new Client();
$client->useApplicationDefaultCredentials();
$client->addScope(Drive::DRIVE);
$driveService = new Drive($client);
# Begin with our last saved start token for this user or the
# current token from getStartPageToken()
$savedStartPageToken = readLine("Enter Start Page Token: ");
$pageToken = $savedStartPageToken;
while ($pageToken != null) {
$response = $driveService->changes->listChanges($pageToken, array(
'spaces' => 'drive'
));
foreach ($response->changes as $change) {
// Process change
printf("Change found for file: %s", $change->fileId);
}
if ($response->newStartPageToken != null) {
// Last page, save this token for the next polling interval
$savedStartPageToken = $response->newStartPageToken;
}
$pageToken = $response->nextPageToken;
}
echo $savedStartPageToken;
} catch(Exception $e) {
echo "Error Message: ".$e;
}
}
require_once 'vendor/autoload.php';
.NET
drive/snippets/drive_v3/DriveV3Snippets/FetchChanges.cs
using Google.Apis.Auth.OAuth2;
using Google.Apis.Drive.v3;
using Google.Apis.Services;
namespace DriveV3Snippets
{
// Class to demonstrate use-case of Drive's fetch changes in file.
public class FetchChanges
{
/// <summary>
/// Retrieve the list of changes for the currently authenticated user.
/// prints changed file's ID
/// </summary>
/// <param name="savedStartPageToken">last saved start token for this user.</param>
/// <returns>saved token for the current state of the account, null otherwise.</returns>
public static string DriveFetchChanges(string savedStartPageToken)
{
try
{
/* Load pre-authorized user credentials from the environment.
TODO(developer) - See https://developers.google.com/identity for
guides on implementing OAuth2 for your application. */
GoogleCredential credential = GoogleCredential.GetApplicationDefault()
.CreateScoped(DriveService.Scope.Drive);
// Create Drive API service.
var service = new DriveService(new BaseClientService.Initializer
{
HttpClientInitializer = credential,
ApplicationName = "Drive API Snippets"
});
// Begin with our last saved start token for this user or the
// current token from GetStartPageToken()
string pageToken = savedStartPageToken;
while (pageToken != null)
{
var request = service.Changes.List(pageToken);
request.Spaces = "drive";
var changes = request.Execute();
foreach (var change in changes.Changes)
{
// Process change
Console.WriteLine("Change found for file: " + change.FileId);
}
if (changes.NewStartPageToken != null)
{
// Last page, save this token for the next polling interval
savedStartPageToken = changes.NewStartPageToken;
}
pageToken = changes.NextPageToken;
}
return savedStartPageToken;
}
catch (Exception e)
{
// TODO(developer) - handle error appropriately
if (e is AggregateException)
{
Console.WriteLine("Credential Not found");
}
else
{
throw;
}
}
return null;
}
}
}
Node.js
drive/snippets/drive_v3/change_snippets/fetch_changes.js
/**
* Retrieve the list of changes for the currently authenticated user.
* @param {string} savedStartPageToken page token got after executing fetch_start_page_token.js file
**/
async function fetchChanges(savedStartPageToken) {
// Get credentials and build service
// TODO (developer) - Use appropriate auth mechanism for your app
const {GoogleAuth} = require('google-auth-library');
const {google} = require('googleapis');
const auth = new GoogleAuth({
scopes: 'https://www.googleapis.com/auth/drive.readonly',
});
const service = google.drive({version: 'v3', auth});
try {
let pageToken = savedStartPageToken;
do {
const res = await service.changes.list({
pageToken: savedStartPageToken,
fields: '*',
});
res.data.changes.forEach((change) => {
console.log('change found for file: ', change.fileId);
});
pageToken = res.data.newStartPageToken;
return pageToken;
} while (pageToken);
} catch (err) {
// TODO(developer) - Handle error
throw err;
}
}
レスポンスの changes コレクションに nextPageToken が含まれている場合があります。nextPageToken がリストに表示されている場合は、次のページの変更を収集するために使用できます。リストにない場合は、クライアント アプリケーションは、今後使用するために newStartPageToken をレスポンスに保存する必要があります。ページトークンが保存されると、クライアント アプリケーションは、今後の変更を再度クエリする準備が整います。
通知を受け取る
changes.watch メソッドを使用して、変更ログの更新をサブスクライブします。通知には変更の詳細は含まれません。新しい変更が利用可能であることを示します。実際の変更を取得するには、変更を取得するで説明されているように変更フィードをポーリングします。
詳細については、リソース変更の通知をご覧ください。