Overview

WalletConnect Dart v2 library for Flutter, heavily inspired by the WalletConnect V2 Javascript Monorepo.

To Use

Pair, Approve, and Sign/Auth

dApp Flow

// To create both an Auth and Sign API, you can use the Web3App
// If you just need one of the other, replace Web3App with SignClient or AuthClient
// SignClient wcClient = await SignClient.createInstance(
// AuthClient wcClient = await AuthClient.createInstance(
Web3App wcClient = await Web3App.createInstance(
  relayUrl: 'wss://relay.walletconnect.com', // The relay websocket URL, leave blank to use the default
  projectId: '123',
  metadata: PairingMetadata(
    name: 'dApp (Requester)',
    description: 'A dapp that can request that transactions be signed',
    url: 'https://walletconnect.com',
    icons: ['https://avatars.githubusercontent.com/u/37784886'],
  ),
);

// For a dApp, you would connect with specific parameters, then display
// the returned URI.
ConnectResponse resp = await wcClient.connect(
  requiredNamespaces: {
    'eip155': RequiredNamespace(
      chains: ['eip155:1'], // Ethereum chain
      methods: ['personal_sign'], // Requestable Methods, see MethodsConstants for reference
      events: ['chainChanged'], // Requestable Events, see EventsConstants for reference
    ),
  },
  optionalNamespaces: {
    'eip155': RequiredNamespace(
      chains: ['eip155:1', 'eip155:5'], // Any other optional Ethereum chain
      methods: ['eth_signTransaction'], // Optional requestable Methods, see MethodsConstants for reference
      events: ['accountsChanged'], // Optional requestable events, see EventsConstants for reference
    ),
  },
);
Uri? uri = resp.uri;

// Once you've display the URI, you can wait for the future, and hide the QR code once you've received session data
final SessionData session = await resp.session.future;

// Now that you have a session, you can request signatures
final dynamic signResponse = await wcClient.request(
  topic: session.topic,
  chainId: 'eip155:1',
  request: SessionRequestParams(
    method: 'eth_signTransaction',
    params: '{json serializable parameters}',
  ),
);
// Unpack, or use the signResponse.
// Structure is dependant upon the JSON RPC call you made.


// You can also request authentication
final AuthRequestResponse authReq = await wcClient.requestAuth(
  params: AuthRequestParams(
    aud: 'http://localhost:3000/login',
    domain: 'localhost:3000',
    chainId: 'eip155:1',
    statement: 'Sign in with your wallet!',
  ),
  pairingTopic: resp.pairingTopic,
);

// Await the auth response using the provided completer
final AuthResponse authResponse = await authResponse.completer.future;
if (authResponse.result != null) {
  // Having a result means you have the signature and it is verified.

  // Retrieve the wallet address from a successful response
  final walletAddress = AddressUtils.getDidAddress(authResponse.result!.p.iss);
}
else {
  // Otherwise, you might have gotten a WalletConnectError if there was un issue verifying the signature.
  final WalletConnectError? error = authResponse.error;
  // Of a JsonRpcError if something went wrong when signing with the wallet.
  final JsonRpcError? error = authResponse.jsonRpcError;
}


// You can also respond to events from the wallet, like session events
wcClient.registerEventHandler(
  chainId: 'eip155:1',
  event: 'accountsChanged',
);
wcClient.onSessionEvent.subscribe((SessionEvent? session) {
  // Do something with the event
});

Wallet Flow

Web3Wallet wcClient = await Web3Wallet.createInstance(
  relayUrl: 'wss://relay.walletconnect.com', // The relay websocket URL, leave blank to use the default
  projectId: '123',
  metadata: PairingMetadata(
    name: 'Wallet (Responder)',
    description: 'A wallet that can be requested to sign transactions',
    url: 'https://walletconnect.com',
    icons: ['https://avatars.githubusercontent.com/u/37784886'],
  ),
);

// For a wallet, setup the proposal handler that will display the proposal to the user after the URI has been scanned.
late int id;
wcClient.onSessionProposal.subscribe((SessionProposal? args) async {
  // Handle UI updates using the args.params
  // Keep track of the args.id for the approval response
  if (args != null) {
    id = args!.id;
    // To check VerifyAPI validation in regards of the dApp is trying to connnect you can check verifyContext
    // More info about VerifyAPI https://docs.walletconnect.com/web3wallet/verify
    final isScamApp = args.verifyContext?.validation.scam;
    final isInvalidApp = args.verifyContext?.validation.invalid;
    final isValidApp = args.verifyContext?.validation.valid;
    final unknown = args.verifyContext?.validation.unknown;
  }
});

// Also setup the methods and chains that your wallet supports
final signRequestHandler = (String topic, dynamic parameters) async {
  // Handling Steps
  // 1. Parse the request, if there are any errors thrown while trying to parse
  // the client will automatically respond to the requester with a 
  // JsonRpcError.invalidParams error
  final parsedResponse = parameters;

  // 1. If you want to fail silently, you can throw a WalletConnectErrorSilent
  if (failSilently) {
    throw WalletConnectErrorSilent();
  }

  // 2. Show a modal to the user with the signature info: Allow approval/rejection
  bool userApproved = await showDialog( // This is an example, you will have to make your own changes to make it work.
    context: context,
    builder: (context) {
      return AlertDialog(
        title: const Text('Sign Transaction'),
        content: SizedBox(
          width: 300,
          height: 350,
          child: Text(parsedResponse.toString()),
        ),
        actions: [
          ElevatedButton(
            onPressed: () => Navigator.pop(context, true),
            child: Text('Accept'),
          ),
          ElevatedButton(
            onPressed: () => Navigator.pop(context, false),
            child: Text('Reject'),
          ),
        ],
      );
    },
  );

  // 3. Respond to the dApp based on user response
  if (userApproved) {
    // Returned value must be a primitive, or a JSON serializable object: Map, List, etc.
    return 'Signed!';
  }
  else {
    // Throw an error if the user rejects the request
    throw Errors.getSdkError(Errors.USER_REJECTED_SIGN);
  }
}
wcClient.registerRequestHandler(
  chainId: 'eip155:1',
  method: 'eth_sendTransaction',
  handler: signRequestHandler,
);

// If you want to the library to handle Namespace validation automatically, 
// you can register your events and accounts like so:
wcClient.registerEventEmitter(
  chainId: 'eip155:1',
  event: 'chainChanged',
);
wcClient.registerAccount(
  chainId: 'eip155:1',
  account: '0xabc',
);

// If your wallet receives a session proposal that it can't make the proper Namespaces for,
// it will broadcast an onSessionProposalError
wcClient.onSessionProposalError.subscribe((SessionProposalError? args) {
  // Handle the error
});

// Setup the auth handling
clientB.onAuthRequest.subscribe((AuthRequest? args) async {

  // This is where you would 
  // 1. Store the information to be signed
  // 2. Display to the user that an auth request has been received

  // You can create the message to be signed in this manner
  String message = clientB.formatAuthMessage(
    iss: TEST_ISSUER_EIP191,
    cacaoPayload: CacaoRequestPayload.fromPayloadParams(
      args!.payloadParams,
    ),
  );
});

// Then, scan the QR code and parse the URI, and pair with the dApp
// On the first pairing, you will immediately receive onSessionProposal and onAuthRequest events.
Uri uri = Uri.parse(scannedUriString);
final PairingInfo pairing = await wcClient.pair(uri: uri);

// Present the UI to the user, and allow them to reject or approve the proposal
final walletNamespaces = {
  'eip155': Namespace(
    accounts: ['eip155:1:abc'],
    methods: ['eth_signTransaction'],
    events: ['accountsChanged'],
  ),
}
await wcClient.approveSession(
  id: id,
  namespaces: walletNamespaces // This will have the accounts requested in params
                               // If you registered correctly events emitters, methods handlers and accounts for your supported chains you can just us `args.params.generatedNamespaces!` value from SessionProposalEvent
);
// Or to reject...
// Error codes and reasons can be found here: https://docs.walletconnect.com/2.0/specs/clients/sign/error-codes
await wcClient.rejectSession(
  id: id,
  reason: Errors.getSdkError(Errors.USER_REJECTED),
);

// For auth, you can do the same thing: Present the UI to them, and have them approve the signature.
// Then respond with that signature. In this example I use EthSigUtil, but you can use any library that can perform
// a personal eth sign.
String sig = EthSigUtil.signPersonalMessage(
  message: Uint8List.fromList(message.codeUnits),
  privateKey: 'PRIVATE_KEY',
);
await wcClient.respondAuthRequest(
  id: args.id,
  iss: 'did:pkh:eip155:1:ETH_ADDRESS',
  signature: CacaoSignature(t: CacaoSignature.EIP191, s: sig),
);
// Or rejected
// Error codes and reasons can be found here: https://docs.walletconnect.com/2.0/specs/clients/sign/error-codes
await wcClient.respondAuthRequest(
  id: args.id,
  iss: 'did:pkh:eip155:1:ETH_ADDRESS',
  error: Errors.getSdkError(Errors.USER_REJECTED_AUTH),
);

// You can also emit events for the dApp
await wcClient.emitSessionEvent(
  topic: sessionTopic,
  chainId: 'eip155:1',
  event: SessionEventParams(
    name: 'chainChanged',
    data: 'a message!',
  ),
);

// Finally, you can disconnect
await wcClient.disconnectSession(
  topic: pairing.topic,
  reason: Errors.getSdkError(Errors.USER_DISCONNECTED),
);

Reconnecting the WebSocket

// If your WebSocket dies, you can reconnect it the with the following method
wcClient.core.relayClient.connect();

Responding to Data Changes (Event Handling)

The dart library has all of the events listed in the specification.

However, instead of using strings to identify the events, each event has it's own dedicated object like so:

wcClient.onSessionEvent.subscribe((SessionEvent? session) {
  // Do something with the event
});

Platform Permissions

MacOS

This library requires that you add the following to your DebugProfile.entitlements and Release.entitlements files so that it can connect to the WebSocket server.

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

To Test

Run tests using flutter test --dart-define=PROJECT_ID=xxx. Expected flutter version is: >3.0.0

To output logs while testing, you can set the core.logger.level = Level.info to see only warnings and errors, or Level.info to see all logs.

Commands Run in CI

• flutter analyze
• dart format --output=none --set-exit-if-changed .

Useful Commands

• flutter pub run build_runner build --delete-conflicting-outputs - Regenerates JSON Generators
• flutter doctor -v - get paths of everything installed.
• flutter pub get
• flutter upgrade
• flutter clean
• flutter pub cache clean
• flutter pub deps
• flutter pub run dependency_validator - show unused dependencies and more
• dart format lib/* -l 120
• flutter analyze