how to send and receive messages in rtm

[Nader2004]

Hello I have been trying to send and receive message through the AgoraRtmChannel Object. But whenever i listen to messages through the onMessageReceived, it tells me that I called the onMessageReceived on null,

Here is the code:

` The client is already initialized and I have also provided a username to  use RTM`
_channel = client.sessionController.value.agoraRtmChannel;
_channel.onMessageReceived = (rtmMessage, member) {
      print(rtmMessage.text);
    };

Here is the error :

The setter 'onMessageReceived=' was called on null.
Receiver: null
Tried calling: onMessageReceived=Closure: (AgoraRtmMessage, AgoraRtmMember) => Null

[Meherdeep]

Hey @Nader2004 , Inside your AgoraClient you can use agoraRtmChannelEventHandler to call any callback from the Agora RTM Channel class.

[Nader2004]

Hey @Meherdeep thanks for replying, I have tried looking for a named argument that have to do anything with rtm messages but couldn't find one except two that are about rtm :

agoraEventHandlers: AgoraEventHandlers(
        rtmpStreamingEvent: ,
        rtmpStreamingStateChanged: ,
     ),

Also how can I send messages then using rtm from UIKit.

[Nader2004]

Hey @Meherdeep thanks for the package update. But is still actually facing the problem of sending messages, when I call sendMessage from AgoraRtmChannel like that : client.sessionController.value.agoraRtmChannel.sendMessage( AgoraRtmMessage.fromText(text));, it fails with error code 102, which according to the agora documentation is about rtm login issue. So is this the right way to send a message or how to resolve that error? Thanks!

[Meherdeep]

You can do a check before sending a message to see if the user has logged in or not.

if(client.sessionController.value.isLoggedIn) {
      client.sessionController.value.agoraRtmChannel.sendMessage(message)
    }

[Nader2004]

hey @Meherdeep I apologize for the late response, I have added the if check but the error still exist. But I did extra observation on the error and discovered that by calling : client.initialize() , it doesn't actually call the Rtm login method.
Here is the code of the initialize() method:

Future<void> initialize() async {
    if (_initialized) {
      return;
    }

    try {
      await _sessionController.initializeEngine(
          agoraConnectionData: agoraConnectionData);
    } catch (e) {
      log("Error while initializing Agora RTC SDK", level: Level.error.value);
    }

    if (agoraConnectionData.rtmEnabled) {
      try {
        await _sessionController.initializeRtm(
            agoraRtmClientEventHandler ?? AgoraRtmClientEventHandler());
      } catch (e) {
        log("Error while initializing Agora RTM SDK. ${e.toString()}",
            level: Level.error.value);
      }
    }

    if (agoraChannelData?.clientRole == ClientRole.Broadcaster ||
        agoraChannelData?.clientRole == null) {
      await _sessionController.askForUserCameraAndMicPermission();
    }
    if (enabledPermission != null) {
      await enabledPermission!.request();
    }

    _sessionController.createEvents(
      agoraRtmChannelEventHandler ?? AgoraRtmChannelEventHandler(),
      agoraEventHandlers ?? AgoraRtcEventHandlers(),
    );

    if (agoraChannelData != null) {
      _sessionController.setChannelProperties(agoraChannelData!);
    }

    await _sessionController.joinVideoChannel();
    _initialized = true;
  }

The important part here is the :

if (agoraConnectionData.rtmEnabled) {
      try {
        await _sessionController.initializeRtm(
            agoraRtmClientEventHandler ?? AgoraRtmClientEventHandler());
      } catch (e) {
        log("Error while initializing Agora RTM SDK. ${e.toString()}",
            level: Level.error.value);
      }
    }

When calling initializeRtm() only the RtmClient is created but there is no callback for the login method:

Future<void> initializeRtm(
      AgoraRtmClientEventHandler agoraRtmClientEventHandler) async {
    value = value.copyWith(
      agoraRtmClient: await AgoraRtmClient.createInstance(
        value.connectionData!.appId,
      ),
    );
    if (value.agoraRtmClient != null) {
      addListener(() {
        createRtmClientEvents(agoraRtmClientEventHandler);
      });
    }
  }

It's just a speculation, maybe the login() method is called elsewhere, I don't know, but the error actually still exists.

[Meherdeep]

Hey @Nader2004, the Rtm login occurs once the user joins the RTC channel. Hence, it's called under the joinChannelSuccess callback.
Can you share your code where you're trying to send a message and your flutter doctor

[Nader2004]

Okay @Meherdeep here is my sample code :

TextEditingController _channelMessageController;
Future<void> _agoraFuture;
AgoraRtmClient rtmClient;
List<String> _messages = []; 

@override
  void initState() {
    _channelMessageController = TextEditingController();
    _agoraFuture = initAgora();
    super.initState();
  }

Future<void> initAgora() async {
    client = AgoraClient(
      agoraChannelData: AgoraChannelData(
        channelProfile: ChannelProfile.LiveBroadcasting,
        clientRole: widget.clientRole,
      ),
      agoraConnectionData: AgoraConnectionData(
        appId: config.appId,
        channelName: widget.channelName,
        tempToken: config.token,
        rtmChannelName: widget.channelName,
        username: _user.username,
      ),
      agoraRtmClientEventHandler: AgoraRtmClientEventHandler(
        onMessageReceived: (message, uid) {
          _messages.add(message.text);
        },
      ),
      agoraRtmChannelEventHandler: AgoraRtmChannelEventHandler(
        onMessageReceived: (rtmMessage, member) {
          _messages.add(rtmMessage.text);
        },
        onMemberJoined: (member)  {
          _messages.add(member.userId + 'joined the channel');
        },
        onMemberLeft: (member)  {
          _messages.add(member.userId + 'left the channel');
        },
      ),
      enabledPermission: [
        Permission.camera,
        Permission.microphone,
      ],
    );
    await client.initialize();
  }

Widget _buildBottomPart() {
    return Align(
      alignment: Alignment.bottomCenter,
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          _buildListScrollView(),
          Container(
            color: Colors.white.withOpacity(0.5),
            height: 1,
            width: MediaQuery.of(context).size.width,
          ),
          Container(
            alignment: Alignment.bottomRight,
            child: Padding(
              padding: const EdgeInsets.symmetric(
                horizontal: 8,
                vertical: 3,
              ),
              child: Row(
                mainAxisAlignment: MainAxisAlignment.end,
                children: <Widget>[
                  Expanded(
                    child: Padding(
                      padding: const EdgeInsets.fromLTRB(0.0, 0, 0, 0),
                      child: TextField(
                        cursorColor: Colors.blue,
                        textInputAction: TextInputAction.send,
                        onSubmitted: (text) {
                          if (client.sessionController.value.isLoggedIn) {
                            client.sessionController.value.agoraRtmChannel
                                .sendMessage(
                              AgoraRtmMessage.fromText(text),
                            );
                          }
                          
                          _channelMessageController.clear();
                        },
                        style: TextStyle(color: Colors.white),
                        controller: _channelMessageController,
                        textCapitalization: TextCapitalization.sentences,
                        decoration: InputDecoration.collapsed(
                          hintText: 'Comment..',
                          hintStyle: TextStyle(color: Colors.white),
                        ),
                      ),
                    ),
                  ),
                ],
              ),
            ),
          ),
        ],
      ),
    );
  }

@override
  void dispose() {
    _channelMessageController.dispose();
    super.dispose();
  }
 
@override
  Widget build(BuildContext context) {
    return FutureBuilder(
      future: _agoraFuture,
      builder: (context, snapshot) {
        if (snapshot.connectionState == ConnectionState.waiting) {
          return Center(
            child: CircularProgressIndicator(),
          );
        }
        return Stack(
          children: [
            AgoraVideoViewer(
              client: client,
            ),
            _buildBottomPart(),
          ],
        );
      },
    );
  }

And here is the doctor :

[√] Flutter (Channel stable, 3.0.0, on Microsoft Windows [Version 10.0.19043.1706], locale en-US)
[!] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
    X cmdline-tools component is missing
      Run `path/to/sdkmanager --install "cmdline-tools;latest"`
      See https://developer.android.com/studio/command-line for more details.
    X Android license status unknown.
      Run `flutter doctor --android-licenses` to accept the SDK licenses.
      See https://flutter.dev/docs/get-started/install/windows#android-setup for more details.
[√] Chrome - develop for the web
[!] Visual Studio - develop for Windows (Visual Studio Build Tools 2017 15.9.27)
    X Visual Studio 2019 or later is required.
      Download at https://visualstudio.microsoft.com/downloads/.
      Please install the "Desktop development with C++" workload, including all of its default components
[√] Android Studio (version 3.3)
[√] VS Code (version 1.67.2)
[√] Connected device (3 available)
[√] HTTP Host Availability

! Doctor found issues in 2 categories.

[Meherdeep]

Hey @Nader2004 Sorry for the late reply. I tried building the sample code that you shared, I just made a small adjustment to the sendMessage logic and I was able to send messages using that. Here's the code for that:

if (client.sessionController.value.isLoggedIn &&
                              client.sessionController.value.isInChannel) {
                            client.sessionController.value.agoraRtmChannel
                                .sendMessage(
                              AgoraRtmMessage.fromText(text),
                            );
                          }

[Meherdeep]

Closing this issue for now. If you're still facing this issue feel free to reopen it.