0
surajlokhandemmew created
ABP Framework version: v8.0.0
UI Type: MVC + Flutter
Database System: MongoDB
Tiered (for MVC) or Auth Server Separated (for Angular): no
Exception message and full stack trace: below is the error and hub code with flutter controller code
[ERROR:flutter/runtime/dart_vm_initializer.cc(41)] Unhandled Exception: Error parsing handshake response: 'type 'Null' is not a subtype of type 'String' in type cast'
public class ChatMaiHub : AbpHub
{
private readonly IIdentityUserRepository _identityUserRepository;
private readonly ILookupNormalizer _lookupNormalizer;
public ChatMaiHub(IIdentityUserRepository identityUserRepository, ILookupNormalizer lookupNormalizer)
{
_identityUserRepository = identityUserRepository;
_lookupNormalizer = lookupNormalizer;
}
public async Task SendMessage(string targetUserName, string message)
{
var targetUser = await _identityUserRepository.FindByNormalizedUserNameAsync(_lookupNormalizer.NormalizeName(targetUserName));
message = $"{CurrentUser.UserName}: {message}";
await Clients
.User(targetUser.Id.ToString())
.SendAsync("ReceiveMessage", message);
}
}
below is flutter controller
import 'package:mailaundry/presentation/models/authview_model.dart';
import 'package:logging/logging.dart';
import 'package:signalr_netcore/signalr_client.dart';
import '../../mylaundryhub/mylaundryhub_gloabelclass/mylaundryhub_prefsname.dart';
class ChatController {
late HubConnection _hubConnection;
final Function(String message) onMessageReceived;
AuthViewModel authViewModel = AuthViewModel();
final transportProtLogger = Logger("SignalR - transport");
final hubProtLogger = Logger("SignalR - hub");
Future<String> getValidAccessToken() async {
// Ensure this method handles the potential null case appropriately.
return await authViewModel.getValidAccessToken() ?? '';
}
ChatController({required this.onMessageReceived}) {
var httpOptions = HttpConnectionOptions(
logger: transportProtLogger,
transport: HttpTransportType.ServerSentEvents,
accessTokenFactory: () async => await getValidAccessToken());
_hubConnection = HubConnectionBuilder()
.withUrl("$api/signalr-hubs/chat-mai", options: httpOptions)
.configureLogging(hubProtLogger)
.build();
_hubConnection.on('ReceiveMessage', (arguments) {
if (arguments != null && arguments.isNotEmpty) {
onMessageReceived(arguments[0] as String);
}
});
_hubConnection.start();
//.catchError((error) {
//print('Connection Failed. Error: $error');
//});
}
Future<void> sendMessage(String targetUserName, String message) async {
if (_hubConnection.state == HubConnectionState.Connected) {
await _hubConnection
.invoke('SendMessage', args: [targetUserName, message]);
} else {
print('Connection is not established. Message not sent.');
// Optionally, implement a retry mechanism or inform the user.
}
}
}
3 Answer(s)
-
0
hi
We aren't familiar with Flutter. Do you get any errors on the backend app?
-
0
no i resolved the error basically had to turn on websocket in IIS, but as this question is already raised i am having another issue , can i ask here or should i raise another question??
-
0
Sure
