locorda_gdrive

Google Drive backend for Locorda CRDT synchronization.

Features

• Google Drive backend — stores RDF sync data in the App Data Folder or a visible Drive folder
• Google Sign-In — uses the official google_sign_in package
• Worker isolate support — all Drive I/O runs in a background isolate/web worker
• Storage layouts — SingleFile (default), ShardDataset, FilePerResource
• Flutter UI — login screen and status widget included
• Localised — English and German

Installation

flutter pub add locorda locorda_gdrive
flutter pub add dev:build_runner dev:locorda_dev

OAuth2 setup required — you must configure platform-specific OAuth2 credentials before GDrive sync will work. See OAuth2 Setup below.

Quick start

1. Run code generation

dart run build_runner build

locorda_dev discovers locorda_gdrive via its worker manifest and automatically includes GDriveWorkerHandler in the generated worker_generated.g.dart — no manual worker code needed.

2. Initialize on the main thread

import 'package:locorda/locorda.dart';
import 'package:locorda_gdrive/locorda_gdrive.dart';
import 'init_locorda.g.dart';  // generated

final locorda = await initLocorda(
  storage: DriftMainHandler(),
  remotes: [await GDriveMainIntegration.create()],
);

GDriveMainIntegration.create() uses the App Data Folder by default — private storage that is invisible to the user in Google Drive UI. See Storage Modes for alternatives.

3. Add the status widget

AppBar(
  actions: [
    MultiBackendStatusWidget(
      registry: locorda.uiAdapterRegistry,
      syncManager: locorda.syncManager,
    ),
  ],
)

Storage Modes

App Data Folder (default, recommended)

Private, isolated storage invisible to users. Uses drive.appdata scope automatically.

// Simplest — uses all defaults
await GDriveMainIntegration.create()

// Equivalent explicit form
await GDriveMainIntegration.create(config: GDriveConfig())

Advantages over a visible folder:

• Invisible to the user — no folder clutter in My Drive
• Faster search (smaller, isolated namespace)
• Only your app can access it

Visible Folder

await GDriveMainIntegration.create(
  config: GDriveConfig.visibleFolder(appFolderName: 'MyApp'),
)

Use when users need direct access to the files (e.g. debugging, manual migration). Uses drive.file scope automatically.

Storage Layouts

Layout controls how RDF resources are packed into Drive files. Configure it inside GDriveConfig:

// SingleFile — everything in one TriG file (default — fewest requests)
GDriveConfig(layout: SingleFile())

// ShardDataset — one TriG file per shard (better for large collections)
GDriveConfig(layout: ShardDataset())

// FilePerResource — one Turtle file per resource (Solid-style interop)
GDriveConfig(layout: FilePerResource())

Advanced Configuration

await GDriveMainIntegration.create(
  config: GDriveConfig(
    typeFolderNames: {
      IriTerm('https://schema.org/Note'): 'notes',
      IriTerm('https://schema.org/Person'): 'contacts',
    },
  ),
)

// Combining visible folder with custom type folders
await GDriveMainIntegration.create(
  config: GDriveConfig.visibleFolder(
    appFolderName: 'MyApp',
    typeFolderNames: {
      IriTerm('https://schema.org/Note'): 'notes',
    },
  ),
)

OAuth2 Setup

Note: OAuth client IDs are configured per platform in native config files, not in Dart code. GDriveMainIntegration reads them automatically.

1. Create a Google Cloud Project

1. Go to Google Cloud Console
2. Create or select a project
3. Enable Google Drive API

2. Create OAuth2 Credentials

Go to APIs & Services → Credentials → Create Credentials → OAuth 2.0 Client ID.

Web:

Type: Web application
Authorized JavaScript origins:
  - http://localhost
  - http://localhost:7357  (replace with your dev port)
  - https://yourdomain.com

Mobile/Desktop:

Type: iOS / Android / Desktop app
(No redirect URI — uses custom URL scheme)

3. Configure Scopes

Scopes are set automatically based on your config:

Config	Scope
GDriveConfig() (App Data Folder)	drive.appdata
GDriveConfig.visibleFolder(...)	drive.file

Always also includes openid for stable user identification.

Enable these scopes on the OAuth consent screen in Google Cloud Console.

4. Platform-Specific Setup

iOS — ios/Runner/Info.plist:

<key>GIDClientID</key>
<string>YOUR-IOS-CLIENT-ID.apps.googleusercontent.com</string>
<key>GIDServerClientID</key>
<string>YOUR-SERVER-CLIENT-ID.apps.googleusercontent.com</string>
<key>CFBundleURLTypes</key>
<array>
  <dict>
    <key>CFBundleTypeRole</key><string>Editor</string>
    <key>CFBundleURLSchemes</key>
    <array>
      <string>com.googleusercontent.apps.YOUR-CLIENT-ID</string>
    </array>
  </dict>
</array>

macOS — macos/Runner/Info.plist with the same keys as iOS, plus entitlements:

<key>keychain-access-groups</key>
<array>
  <string>$(AppIdentifierPrefix)com.google.GIDSignIn</string>
</array>

Android — no additional setup needed with default configuration.

Web — web/index.html before </head>:

<meta name="google-signin-client_id" content="YOUR-CLIENT-ID.apps.googleusercontent.com">
<script src="https://accounts.google.com/gsi/client" async defer></script>

On web the sign-in button must be rendered via the GIS SDK:

if (kIsWeb) {
  return renderButton();  // from google_sign_in_web
}

See google_sign_in documentation for full platform setup.

Architecture

┌─────────────────────┐
│   Main Thread       │
│  ┌──────────────┐   │
│  │ GDriveAuth   │───┼──── OAuth2 Flow
│  └──────┬───────┘   │
│         │ credentials via channel
└─────────┼───────────┘
┌─────────▼───────────┐
│   Worker Thread     │
│  ┌──────────────┐   │
│  │ GDriveWorker │───┼──── Drive API
│  │ Handler      │   │     (RDF files)
│  └──────────────┘   │
└─────────────────────┘

All Drive I/O happens in the worker thread. The main thread only handles the OAuth2 sign-in flow and forwards credentials via a typed channel.

License

See LICENSE file in repository root.