Fluttter Duit Backend-driven UI

Overview

Duit enables backend-driven UI in Flutter applications. The server controls both data and layout via JSON, allowing UI updates without app releases.

Quick Start

1. Add dependency to pubspec.yaml
2. Initialize DuitRegistry (optional: with themes/custom widgets)
3. Create XDriver (HTTP, WebSocket, or static)
4. Wrap UI in DuitViewHost
5. Server sends JSON layouts → Duit renders them

Prerequisites

SDK Requirements

- Dart SDK: >=3.4.4 <4.0.0
- Flutter: >=3.24.0

Add Dependency

flutter pub add flutter_duit

Install:

flutter pub get

Basic Integration

Minimal Setup

import 'package:flutter/material.dart';
import 'package:flutter_duit/flutter_duit.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: DuitViewHost.withDriver(
          driver: XDriver.static({
            "type": "Text",
            "id": "1",
            "attributes": {"data": "Hello, World!"},
          }),
        ),
      ),
    );
  }
}

Driver Lifecycle Management

Always dispose drivers to prevent memory leaks:

class MyWidgetState extends State<MyWidget> {
  late final XDriver driver;

  @override
  void initState() {
    super.initState();
    driver = XDriver.static(/* ... */);
  }

  @override
  void dispose() {
    driver.dispose();
    super.dispose();
  }
}

Transport Configuration

HTTP Transport

Fetch layouts from REST API endpoints:

final driver = XDriver(
  transportManager: HttpTransportManager(
    options: HttpTransportOptions(
      baseUrl: 'https://api.example.com/view',
      headers: {
        'Authorization': 'Bearer $token',
        'Content-Type': 'application/json',
      },
    ),
  ),
);

WebSocket Transport

Real-time bidirectional communication:

final driver = XDriver(
  transportManager: WSTransportManager(
    options: WSTransportOptions(
      url: 'wss://api.example.com/ws',
      headers: {
        'Authorization': 'Bearer $token',
      },
      reconnectInterval: Duration(seconds: 5),
      heartbeatInterval: Duration(seconds: 30),
    ),
  ),
);

Static/Stub Transport

For testing or local layouts:

final driver = XDriver.static(
  layoutJson,
);

Custom Decoder/Encoder

import 'dart:convert';
import 'dart:typed_data';

class CustomDecoder extends Converter<Uint8List, Map<String, dynamic>> {
  @override
  Map<String, dynamic> convert(Uint8List input) {
    // Custom decode logic
    return jsonDecode(utf8.decode(input));
  }
}

final driver = XDriver(
  transportManager: HttpTransportManager(
    options: HttpTransportOptions(
      baseUrl: 'https://api.example.com',
      decoder: CustomDecoder(),
    ),
  ),
);

Custom Transport

Create your own transport implementation if needed:

class MyCustomTransportManager with TransportCapabilityDelegate {
  @override
  void linkDriver(UIDriver driver) {
    // Implement linkDriver method
  }

  @override
  Stream<Map<String, dynamic>> connect({
    Map<String, dynamic>? initialRequestData,
    Map<String, dynamic>? staticContent,
  }) async* {
    // Implement connect method
  }

  @override
  Future<Map<String, dynamic>?> executeRemoteAction(
    ServerAction action,
    Map<String, dynamic> payload,
  ) async {
    //Implement executeRemoteAction method
  }

  @override
  Future<Map<String, dynamic>?> request(
    String url,
    Map<String, dynamic> meta,
    Map<String, dynamic> body,
  ) async {
    //Implement request method
  }

  @override
  void releaseResources() {
    // Implement linkDriver method
  }
}

Custom Widgets

Create and register Custom Widget

import 'package:flutter_duit/flutter_duit.dart';

// 1. Define custom widget
class MyCustomWidget extends StatelessWidget {
  final ViewAttribute attributes;

  const MyCustomWidget({
    required this.attributes,
    super.key,
  });

  @override
  Widget build(BuildContext context) {
    final attrs = attributes.payload;
    return Container(
      child: Text(attrs.getString(key: "message")),
    );
  }
}

// 2. Create build factory fn for widget
Widget myCustomBuildFactory(ElementPropertyView model) {
    if (model.isControlled) {
        return MyCustomWidget(
            attributes: model.attributes,
        );
    } else {
        return const SizedBox.shrink();
    }
}

// 3. Register build-fn
void main() async {
  WidgetsFlutterBinding.ensureInitialized();

  DuitRegistry.register(
    "MyCustomWidget",
    buildFactory: myCustomBuildFactory,
  );

  runApp(const MyApp());
}

Components

Components registration

Components allow you to create reusable UI templates that can be referenced by a tag and populated with dynamic data.

import 'package:flutter_duit/flutter_duit.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();

  // Define component template
  final cardComponent = {
    "tag": "CardComponent",
    "layoutRoot": {
      "type": "Container",
      "id": "cardContainer",
      "controlled": false,
      "attributes": {
        "padding": {"all": 16},
        "margin": {"all": 8},
        "decoration": {
          "borderRadius": 12,
          "color": "#FFFFFF",
          "boxShadow": [
            {
              "color": "#00000033",
              "blurRadius": 6,
              "offset": {"dx": 0, "dy": 2},
            },
          ],
        },
      },
      "children": [
        {
          "type": "Text",
          "id": "cardTitle",
          "controlled": false,
          "attributes": {
            "data": {
              "style": {
                "fontSize": 18,
                "fontWeight": "w600",
                "color": "#333333",
              },
            },
            "refs": [
              {
                "objectKey": "title",
                "attributeKey": "data",
              },
            ],
          },
        },
        {
          "type": "Text",
          "id": "cardDescription",
          "controlled": false,
          "attributes": {
            "data": {
              "style": {
                "fontSize": 14,
                "color": "#666666",
              },
            },
            "refs": [
              {
                "objectKey": "description",
                "attributeKey": "data",
              },
            ],
          },
        },
      ],
    },
  };

  // Register the component
  await DuitRegistry.registerComponents([cardComponent]);

  runApp(const MyApp());
}

// Usage in JSON layout from server:
// {
//   "type": "Component",
//   "id": "card1",
//   "tag": "CardComponent",
//   "data": {
//     "title": "Hello World",
//     "description": "This is a card component"
//   }
// }

Key concepts:

• tag: Unique identifier for the component
• layoutRoot: Root element of the component template
• refs: References to dynamic data passed via the data field
• objectKey: Key in the data object
• attributeKey: Attribute in the widget to bind to
• defaultValue: Optional default value if data key is missing

You can register multiple components at once:

await DuitRegistry.registerComponents([
  cardComponent,
  buttonComponent,
  listItemComponent,
]);

When to Use This Skill

Use this skill when:

• Integration flutter_duit library into project
• Custom widet creation
• Components registration
• Basic framework behavior overriding via capabilities implementation
• Need help with the framework API

Resources

Reference Documentation

• capabilities.md — Notes about capability-based design and core framework parts overriding
• troubleshooting.md - Notes about common issues in framework integration
• environvent_vars.md — Notes about avalilable env variables and its usage
• public_api.md — Notes about driver public API
• https://duit.pro/docs/en — official documentation site