flutter_socket_io : My event triggers, my JSON is OK, but the message is not sent - flutter

Question

I have a problem using flutter_socket_io. My event triggers, my message is OK, all seems to be OK, but the message is not published.
Here is my log :
D/FlutterSocketIoPlugin: FlutterSocketIoPlugin(22753): onMethodCall: socketSendMessage - domain:
<MY_URL> - with namespace: /
D/FlutterSocketIoPlugin: TOTAL SOCKETS: (22753): 1
D/FlutterSocketIoPlugin: SocketIO(22753): socket id: <MY_URL> is connected: true
D/FlutterSocketIoPlugin: sendMessage(22753): Event: chat.sendMessage - with message: {"chat": "5da02fec8216246456198e19", "sender": {"id": "5c014a1d43b6804ed7b642b1", "username": "Yowims", "image": {"url": "<IMAGE_URL>"}}, "state": "send", "message": "zahtrz", "sendDate": "2020-04-03T17:04:58.203404"}
D/FlutterSocketIoPlugin: FlutterSocketIoPlugin(22753): onMethodCall: socketSendMessage - domain:
<MY_URL> - with namespace: /
D/FlutterSocketIoPlugin: TOTAL SOCKETS: (22753): 1
D/FlutterSocketIoPlugin: SocketIO(22753): socket id: <MY_URL> is connected: true
D/FlutterSocketIoPlugin: sendMessage(22753): Event: chat.receiveMessage - with message: {"chat": "5da02fec8216246456198e19", "sender": {"id": "5c014a1d43b6804ed7b642b1", "username": "Yowims", "image": {"url": "<IMAGE_URL>"}}, "state": "send", "message": "zahtrz", "sendDate": "2020-04-03T17:04:58.203404"}
Here are the methods I call :
SocketIO socketIO;
_connectSocket() {
socketIO = SocketIOManager().createSocketIO(wsAdd, "/");
socketIO.init();
_subscribes();
socketIO.connect();
}
_subscribes() {
if (socketIO != null) {
socketIO.subscribe('chat.sendMessage', _onSendChatMessage);
socketIO.subscribe("chat.receiveMessage", _onReceiveChatMessage);
}
}
void _onReceiveChatMessage(dynamic message) {
print("--- Message reçu! Actualisation... ---");
_getMessagesByChatId(chatStateId);
}
void _onSendChatMessage(String msg) async {
if (socketIO != null) {
Map<String,dynamic> chatUser = ({
'"id"': '"${user.id}"',
'"username"': '"${user.username}"',
'"image"': {
'"url"':'"${user.image.url}"'
}
});
String currentDate = DateTime.now().toIso8601String();
Map<String,dynamic> thisJson = {
'"chat"': '"${this.chatStateId}"',
'"sender"': chatUser,
'"state"': '"send"',
'"message"': '"$msg"',
'"sendDate"': '"$currentDate"'
};
socketIO.sendMessage("chat.sendMessage", thisJson.toString());
socketIO.sendMessage("chat.receiveMessage", thisJson.toString());
sendController.clear();
}
}
My formating is quite gross, but I have to do it like this otherwise my program doesn't add quotes at the right spots.
And here is the widget where I call the method to send my message :
SizedBox(
width: 50,
child: FlatButton(
child: Icon(Icons.send),
onPressed: (){
_onSendChatMessage(sendController.text);
},
),
)

Answer 1

Finally I managed to find what the problem was: my message was correctly sent, but the server wasn't able to process it because my server wasn't prepared to receive messages from mobile devices.
Some modifications within the server's code were able to solve my problem.