This guide is for integrating Ditto into an existing Flutter application. If you’re looking to get started quickly with a brand new Flutter app, follow the Flutter QuickStart.

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Prerequisites

Before you begin, ensure you have the following installed:

• Code editor (preferably Visual Studio Code or Android Studio)
• Flutter SDK (version 3.19.0 - 3.24.5)
• An existing Flutter application to integrate Ditto into
• Ditto Portal account with a Ditto App (see Getting SDK Connection Details)

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Android

• Android Studio installed on your machine
• A physical Android device or Android emulator
• Upgrade your Kotlin Gradle version to 1.9.20 or later
  1. Navigate to the root folder
  2. Open ./android/settings.gradle
  3. Update the org.jetbrains.kotlin.android plugin to 1.9.20
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     plugins {
         // ...
         id "org.jetbrains.kotlin.android" version "1.9.20" apply false
     }
     

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iOS

• macOS with the latest version of Xcode installed
• A physical iOS device or an iOS simulator

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Web

• Ensure you have Flutter SDK version 3.22.0 - 3.24.5 installed
• Follow the guide for Web Browser Support

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Step 1: Add the Ditto Dependency

flutter pub add ditto_live
flutter pub add permission_handler

<key>NSBluetoothAlwaysUsageDescription</key>
<string>Uses Bluetooth to connect and sync with nearby devices</string>
<key>NSBluetoothPeripheralUsageDescription</key>
<string>Uses Bluetooth to connect and sync with nearby devices</string>
<key>NSLocalNetworkUsageDescription</key>
<string>Uses WiFi to connect and sync with nearby devices</string>
<key>NSBonjourServices</key>
<array>
  <string>_http-alt._tcp.</string>
</array>

<uses-permission android:name="android.permission.BLUETOOTH"
        android:maxSdkVersion="30" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"
        android:maxSdkVersion="30" />
<uses-permission android:name="android.permission.BLUETOOTH_ADVERTISE"
        tools:targetApi="s" />
<uses-permission android:name="android.permission.BLUETOOTH_CONNECT"
        tools:targetApi="s" />
<uses-permission android:name="android.permission.BLUETOOTH_SCAN"
        android:usesPermissionFlags="neverForLocation"
        tools:targetApi="s" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"
        android:maxSdkVersion="32" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"
        android:maxSdkVersion="30" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_MULTICAST_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
<uses-permission android:name="android.permission.NEARBY_WIFI_DEVICES"
        android:usesPermissionFlags="neverForLocation"
        tools:targetApi="tiramisu" />

<uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
<uses-permission android:name="android.permission.FOREGROUND_SERVICE_CONNECTED_DEVICE" tools:targetApi="upside_down_cake" />
<uses-permission android:name="android.permission.POST_NOTIFICATIONS" tools:targetApi="tiramisu" />

<application ...>
    <service
        android:name="live.ditto.transports.foregroundservice.DefaultDittoForegroundService"
        android:exported="false"
        android:foregroundServiceType="connectedDevice"
        android:stopWithTask="true">
        <meta-data android:name="notificationChannelName" android:value="Background Data Sync" />
        <meta-data android:name="notificationChannelId" android:value="BackgroundDataSyncId" />
        <meta-data android:name="smallIcon" android:resource="@drawable/small_app_icon" />
        <meta-data android:name="notificationTitle" android:value="Syncing Data" />
        <meta-data android:name="notificationText" android:value="Syncing data across connected devices" />
        <meta-data android:name="notificationId" android:value="1001" />
    </service>
</application>

​

Step 2: Obtain Ditto Credentials

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Step 3: Import & Initialize Ditto

import 'package:ditto_live/ditto_live.dart';

import 'package:flutter/foundation.dart';
import 'package:permission_handler/permission_handler.dart';

await Ditto.init();

final identity = OnlinePlaygroundIdentity(
    appId: "REPLACE_ME_WITH_YOUR_APP_ID",
    token: "REPLACE_ME_WITH_YOUR_PLAYGROUND_TOKEN",
    customAuthUrl: "REPLACE_ME_WITH_YOUR_AUTH_URL",
    enableDittoCloudSync: false // This is required to be set to false to use the correct URLs
);
final ditto = await Ditto.open(identity);

ditto.updateTransportConfig((config) {
  // Set the Ditto Websocket URL
  config.connect.webSocketUrls.add("wss://REPLACE_ME_WITH_YOUR_WEBSOCKET_URL");
});

// Disable DQL strict mode so that collection definitions are not required in DQL queries
await ditto.store.execute("ALTER SYSTEM SET DQL_STRICT_MODE = false");

ditto.startSync();

​

Step 4: Creating and Reading Data

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Insert Data

To insert data into the Ditto store, use the following example. This demonstrates inserting a document into a collection named items:

Future<void> insertData() async {
  final item = {'name': 'Sample Item', 'value': 100};
  await ditto.store.execute(
    "INSERT INTO items VALUES (:item)",
    arguments: {"item": item},
  );
}

Call the insertData function wherever appropriate in your application, such as in a button press handler.

FloatingActionButton(
  onPressed: insertData,
  child: Icon(Icons.add),
)

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Obseve Data Store Changes

To observe changes in the data store, register an observer. This example sets up an observer to listen for changes in the items collection:

void observeData() {
  final observer = ditto.store.registerObserver(
    "SELECT * FROM items",
    onChange: (event) {
	    // Handle data changed event
	    print("data changed");
	  },
  );
}

Call the observeData function, typically in the initState method of a stateful widget to start observing when the widget is initialized.

@override
void initState() {
  super.initState();
  observeData();
}

Remember to cancel your observer in your widget’s dispose() method to prevent resource leaks

@override
void dispose() {
  _observer.cancel();
  super.dispose();
}

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Step 5: Syncing Data

To keep your data in sync across devices and with Ditto Server, you need to register sync subscriptions. Sync subscriptions define the specific data that should be automatically synchronized to the device.

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Starting Sync

To start sync on the device you need to call startSync. This enables this device to sync data with other peers including the Ditto Cloud.

ditto.startSync();

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Registering a Subscription

Register a subscription to a collection to keep the data in sync. Below is an example of how to register a subscription to the items collection:

void syncData() {
  ditto.sync.registerSubscription("SELECT * FROM items");
}

Call the syncData function, typically when initializing your Ditto instance.

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Syncing Data Offline

Once your application is syncing data using Ditto, you can deploy it to multiple local devices, Android emulators, or iOS simulators. You can then disable the internet to observe the devices syncing offline.

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Step 6: Web Browser Support

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Web Assets

When Ditto is used on the web, it needs to download and initialize assets for its WebAssembly binary. This happens automatically when calling await Ditto.init(). By default, assets are bundled with the application and loaded from the same web server that serves the application. After running flutter build web, you can find those in the build/web/assets/packages/ditto_live/lib/assets directory.

Alternatively, you can host the contents of that directory on a CDN or other web server and configure Ditto to load assets from there. All contents of the directory, excluding the ditto.wasm file itself, must be reachable at the URL given by the wasmShimUrl parameter. The ditto.wasm file can be served from a separate URL given by the wasmUrl parameter.

Configuration for loading all assets from a CDN:

await Ditto.init(
  wasmUrl: 'https://your-cdn.com/ditto-assets/ditto.wasm',
  wasmShimUrl: 'https://your-cdn.com/ditto-assets/',
);

Please consider your application’s loading UI while downloading the assets as it may take a few seconds to download and initialize the WebAssembly binary.

It is strongly recommended to serve assets using a web server or CDN that supports compression. This will significantly reduce the download size of the assets and thereby the loading time of your application.

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Disable Peer to Peer

On the web, Ditto only eupports syncing with the Ditto cloud and does not directly connect to other devices. Make sure that your app only enables peer-to-peer transports on mobile platforms.

final ditto = await Ditto.init(
  wasmUrl: 'https://your-cdn.com/ditto-assets/ditto.wasm',
  wasmShimUrl: 'https://your-cdn.com/ditto-assets/',
);

final connect = Connect(webSocketUrls: {"wss://REPLACE_ME_WITH_YOUR_WEBSOCKET_URL"});

// Only enable P2P transports on mobile or desktop
if (!kIsWeb) {
  final peerToPeer = PeerToPeer.all();
}

ditto.transportConfig = TransportConfig(peerToPeer: peerToPeer, connect: connect);
ditto.startSync();

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Considerations for Web

• Flutter for Web is designed to work seamlessly with the Ditto cloud. Due to browser restrictions, direct peer-to-peer synchronization with other devices is not supported.
• The web platform utilizes an in-memory Ditto store, meaning data is not retained across page reloads.
• Ditto’s Flutter SDK currently supports the default build mode for the web.
• When developing with Flutter’s development server, it is required to quit and restart the server after making changes to the source code of your app (support for hot restart is in development).

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Step 7: Troubleshooting

• Ensure that all dependencies are up-to-date by updating to the latest version.
• Contact the Ditto team through Contact Us