socket_io_client_flutter

Now available as a Flutter package from pub.dev.

2.x.x version has sound null safety. It can be included in pubspec.yaml as:

dependencies:
  socket_io_client_flutter: ^2.0.0

Dart 3 requires sound null safety and does not support no null safety and unsound (mixed) null safety. Flutter versions that use Dart 3 will only work with socket_io_client_flutter 2.x.x. Flutter versions that use Dart 2.12 and above should work with socket_io_client_flutter 2.x.x, too.

1.x.x version does not have null safety and supports no null safety and unsound (mixed) null safety. It can be included in pubspec.yaml as:

dependencies:
  socket_io_client_flutter: ^1.0.2

Dart 1 and Dart 2 require no null safety. Dart 2.12 and above supports no null safety and both unsound (mixed) and sound null safety. Some earlier Flutter versions that use Dart 2.12 and above run socket_io_client_flutter 1.x.x automatically but more recent Flutter versions that use Dart 2.12 and above require "--no-sound-null-safety" argument to run socket_io_client_flutter 1.x.x.

Original release comment: Port socket.io-client-dart to Flutter without null safety, compatible with Flutter 1.22.6 (no null safety) and Flutter 3.0.2 (supports mixed null safety). Add harmless long-polling extensions for xibbit.

In 1.x.x and 2.x.x versions, it is included in code as:

import 'package:socket_io_client_flutter/socket_io_client_flutter.dart';

socket.io-client-dart

Port of awesome JavaScript Node.js library - Socket.io-client v2.0.1~v3.0.3 - in Dart

Version info:

socket.io-client-dart	Socket.io Server
v0.9.* ~ v1.*	v2.*
v2.*	v3.* & v4.*

Usage

Dart Server

import 'package:socket_io/socket_io.dart';

main() {
  // Dart server
  var io = Server();
  var nsp = io.of('/some');
  nsp.on('connection', (client) {
    print('connection /some');
    client.on('msg', (data) {
      print('data from /some => $data');
      client.emit('fromServer', "ok 2");
    });
  });
  io.on('connection', (client) {
    print('connection default namespace');
    client.on('msg', (data) {
      print('data from default => $data');
      client.emit('fromServer', "ok");
    });
  });
  io.listen(3000);
}

Dart Client

import 'package:socket_io_client/socket_io_client.dart' as IO;

main() {
  // Dart client
  IO.Socket socket = IO.io('http://localhost:3000');
  socket.onConnect((_) {
    print('connect');
    socket.emit('msg', 'test');
  });
  socket.on('event', (data) => print(data));
  socket.onDisconnect((_) => print('disconnect'));
  socket.on('fromServer', (_) => print(_));
}

Connect manually

To connect the socket manually, set the option autoConnect: false and call .connect().

For example,

Socket socket = io('http://localhost:3000', 
    OptionBuilder()
      .setTransports(['websocket']) // for Flutter or Dart VM
      .disableAutoConnect()  // disable auto-connection
      .setExtraHeaders({'foo': 'bar'}) // optional
      .build()
  );
socket.connect();

Note that .connect() should not be called if autoConnect: true (by default, it's enabled to true), as this will cause all event handlers to get registered/fired twice. See Issue #33.

Update the extra headers

Socket socket = ... // Create socket.
socket.io.options['extraHeaders'] = {'foo': 'bar'}; // Update the extra headers.
socket.io..disconnect()..connect(); // Reconnect the socket manually.

Emit with acknowledgement

Socket socket = ... // Create socket.
socket.onConnect((_) {
    print('connect');
    socket.emitWithAck('msg', 'init', ack: (data) {
        print('ack $data') ;
        if (data != null) {
          print('from server $data');
        } else {
          print("Null") ;
        }
    });
});

Socket connection events

These events can be listened on.

const List EVENTS = [
  'connect',
  'connect_error',
  'connect_timeout',
  'connecting',
  'disconnect',
  'error',
  'reconnect',
  'reconnect_attempt',
  'reconnect_failed',
  'reconnect_error',
  'reconnecting',
  'ping',
  'pong'
];

// Replace 'onConnect' with any of the above events.
socket.onConnect((_) {
    print('connect');
});

Acknowledge with the socket server that an event has been received.

socket.on('eventName', (data) {
    final dataList = data as List;
    final ack = dataList.last as Function;
    ack(null);
});

Usage (Flutter)

In Flutter env. not (Flutter Web env.) it only works with dart:io websocket, not with dart:html websocket or Ajax (XHR), so in this case you have to add setTransports(['websocket']) when creates the socket instance.

For example,

IO.Socket socket = IO.io('http://localhost:3000',
  OptionBuilder()
      .setTransports(['websocket']) // for Flutter or Dart VM
      .setExtraHeaders({'foo': 'bar'}) // optional
      .build());

Usage with stream and streambuilder in Flutter

import 'dart:async';


// STEP1:  Stream setup
class StreamSocket{
  final _socketResponse= StreamController<String>();

  void Function(String) get addResponse => _socketResponse.sink.add;

  Stream<String> get getResponse => _socketResponse.stream;

  void dispose(){
    _socketResponse.close();
  }
}

StreamSocket streamSocket =StreamSocket();

//STEP2: Add this function in main function in main.dart file and add incoming data to the stream
void connectAndListen(){
  IO.Socket socket = IO.io('http://localhost:3000',
      OptionBuilder()
       .setTransports(['websocket']).build());

    socket.onConnect((_) {
     print('connect');
     socket.emit('msg', 'test');
    });

    //When an event recieved from server, data is added to the stream
    socket.on('event', (data) => streamSocket.addResponse);
    socket.onDisconnect((_) => print('disconnect'));

}

//Step3: Build widgets with streambuilder

class BuildWithSocketStream extends StatelessWidget {
  const BuildWithSocketStream({Key key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Container(
      child: StreamBuilder(
        stream: streamSocket.getResponse ,
        builder: (BuildContext context, AsyncSnapshot<String> snapshot){
          return Container(
            child: snapshot.data,
          );
        },
      ),
    );
  }
}

Troubleshooting

Cannot connect "https" server or self-signed certificate server

• Refer to https://github.com/dart-lang/sdk/issues/34284 issue. The workround is to use the following code provided by @lehno on #84

class MyHttpOverrides extends HttpOverrides {
  @override
  HttpClient createHttpClient(SecurityContext? context) {
    return super.createHttpClient(context)
      ..badCertificateCallback =
          (X509Certificate cert, String host, int port) => true;
  }
}

void main() {
  HttpOverrides.global = MyHttpOverrides();
  runApp(MyApp());
}

Memory leak issues in iOS when closing socket.

• Refer to https://github.com/rikulo/socket.io-client-dart/issues/108 issue. Please use socket.dispose() instead of socket.close() or socket.disconnect() to solve the memory leak issue on iOS.

Connect_error on MacOS with SocketException: Connection failed

• Refer to https://github.com/flutter/flutter/issues/47606#issuecomment-568522318 issue.

By adding the following key into the to file *.entitlements under directory macos/Runner/

<key>com.apple.security.network.client</key>
<true/>

For more details, please take a look at https://flutter.dev/desktop#setting-up-entitlements

Can't connect socket server on Flutter with Insecure HTTP connection

• Refer to https://flutter.dev/docs/release/breaking-changes/network-policy-ios-android

The HTTP connections are disabled by default on iOS and Android, so here is a workaround to this issue, which mentioned on stack overflow

Notes to Contributors

Fork socket.io-client-dart

If you'd like to contribute back to the core, you can fork this repository and send us a pull request, when it is ready.

If you are new to Git or GitHub, please read this guide first.

Who Uses

• Quire - a simple, collaborative, multi-level task management tool.
• KEIKAI - a web spreadsheet for Big Data.

Socket.io Dart Server

• socket.io-dart

Contributors

• Thanks @felangel for https://github.com/rikulo/socket.io-client-dart/issues/7
• Thanks @Oskang09 for https://github.com/rikulo/socket.io-client-dart/issues/21
• Thanks @bruce3x for https://github.com/rikulo/socket.io-client-dart/issues/25
• Thanks @Kavantix for https://github.com/rikulo/socket.io-client-dart/issues/26
• Thanks @luandnguyen for https://github.com/rikulo/socket.io-client-dart/issues/59
• Thanks @jorgefspereira for https://github.com/rikulo/socket.io-client-dart/pull/177
• Thanks @fzyzcjy for https://github.com/rikulo/socket.io-client-dart/pull/188
• Thanks @darwin-morocho for https://github.com/rikulo/socket.io-client-dart/pull/189
• Thanks @chatziko for https://github.com/rikulo/socket.io-client-dart/pull/237