chatbot_flutter_onsend.dart

void onSend(ChatMessage message) async {
    print(message.toJson());
    setState(() {
      messages = [...messages, message];
      print(messages.length);
    });
    sendMessage(message.text);
  }

void initDio() {
    BaseOptions options = BaseOptions(
      baseUrl: "https://seusite.com/seu_backend",
      connectTimeout: 10000,
    );
    _dio = new Dio(options);
}

Future<void> sendMessage(String msg) async {
    Response response = await _dio.get("?msg=${Uri.encodeFull(msg)}");
    print(response.data.toString());
    setState(() {
      messages = [
        ...messages,
        ChatMessage(text: response.data.toString(), user: bot)
      ];
    });
  }