LiveData 被多次调用

Question

I am posting this after much research in SO.

I have a add button in my page.When I am clicking the add button for the first time, everything is fine. But when I am clicking the add button for the next time in the same page, the add button callback livedata (saveDeviceLiveData) is getting called twice and also the service is getting called twice, for the 3rd time thrice and so on.

The same case is happening for remove button too. I am not able to get what wrong I am doing.

Here is the add button code in the viewmodel:

/***Adding Device****/
private val _saveDeviceLiveData = MutableLiveData<Event<AddDeviceResponseModel>>()
val saveDeviceLiveData: LiveData<Event<AddDeviceResponseModel>>
    get() = _saveDeviceLiveData

private lateinit var addDeviceModel: LiveData<AddDeviceResponseModel>
private val addDeviceObserver = Observer<AddDeviceResponseModel> {
    _saveDeviceLiveData.value = Event(it)
}

fun onClickAddNewDevice(context: Context , isOverride: Boolean) {
    val addDeviceRequestModel = AddDeviceRequestModel(
        deviceName = URLEncoder.encode(PushNotificationUtils.getDeviceName(), "utf-8"),
        deviceType = PushNotificationUtils.getDeviceType(),
        deviceModelName = PushNotificationUtils.getDeviceModelName(context),
        osVersion = PushNotificationUtils.getOSVersion(),
        deviceToken = getFireBaseToken(),
        override = if (isOverride) "y" else "n"
    )
    addDeviceModel =
        notificationSettingsUseCase.addNewDevice(addDeviceRequestModel)//This is the service call
    if (addDeviceModel.hasObservers()) {
        addDeviceModel.removeObserver(addDeviceObserver)
    }
    addDeviceModel.observeForever(addDeviceObserver)
}

And I am observing the livedata in the fragment as:

/**Callback of save device***/
notificationSettingsViewModel.saveDeviceLiveData.observe(
    viewLifecycleOwner,
    Observer {
        it?.getContentIfNotHandled()?.let { responseStatus ->
            if (responseStatus.statusCode.equals(RESPONSE_STATUS_CODE)) {
                requireActivity().toastMessageOtp(responseStatus.statusMessage.toString())
                notificationSettingsViewModel.getDeviceList()
            }else{
                if(responseStatus.statusCode.equals(RESPONSE_STATUS_CODE_DEVICE_OVERRIDING)){
                    showDeviceOverridingAlert(requireContext() ,getString(R.string.alert_overriding_title) ,
                        responseStatus.errorModel?.dtoErrorMsg.toString()
                    )
                }
            }
        }
    })

And here is the add click of the button:

fun invokeAddDeviceCall(isOverride: Boolean){
    val isNotificationEnabled = isNotificationEnabled(requireContext())
    isNotificationEnabled?.let {
        if (it) {
            //Add the device
            if ((viewModel as NotificationSettingsViewModel).getTotalDeviceCount() >= 5) {
                /***Max device reached***/
                showMaxDeviceLimitDialog(requireContext())
            } else {
                (viewModel as NotificationSettingsViewModel).onClickAddNewDevice(requireContext() , isOverride)
            }
        } else {
            enableNotificationAlert(requireContext())
        }
    }
}

Answer 1

I am posting this after much research in SO.

I have a add button in my page.When I am clicking the add button for the first time, everything is fine. But when I am clicking the add button for the next time in the same page, the add button callback livedata (saveDeviceLiveData) is getting called twice and also the service is getting called twice, for the 3rd time thrice and so on.

The same case is happening for remove button too. I am not able to get what wrong I am doing.

Here is the add button code in the viewmodel:

/***Adding Device****/
private val _saveDeviceLiveData = MutableLiveData<Event<AddDeviceResponseModel>>()
val saveDeviceLiveData: LiveData<Event<AddDeviceResponseModel>>
    get() = _saveDeviceLiveData

private lateinit var addDeviceModel: LiveData<AddDeviceResponseModel>
private val addDeviceObserver = Observer<AddDeviceResponseModel> {
    _saveDeviceLiveData.value = Event(it)
}

fun onClickAddNewDevice(context: Context , isOverride: Boolean) {
    val addDeviceRequestModel = AddDeviceRequestModel(
        deviceName = URLEncoder.encode(PushNotificationUtils.getDeviceName(), "utf-8"),
        deviceType = PushNotificationUtils.getDeviceType(),
        deviceModelName = PushNotificationUtils.getDeviceModelName(context),
        osVersion = PushNotificationUtils.getOSVersion(),
        deviceToken = getFireBaseToken(),
        override = if (isOverride) "y" else "n"
    )
    addDeviceModel =
        notificationSettingsUseCase.addNewDevice(addDeviceRequestModel)//This is the service call
    if (addDeviceModel.hasObservers()) {
        addDeviceModel.removeObserver(addDeviceObserver)
    }
    addDeviceModel.observeForever(addDeviceObserver)
}

And I am observing the livedata in the fragment as:

/**Callback of save device***/
notificationSettingsViewModel.saveDeviceLiveData.observe(
    viewLifecycleOwner,
    Observer {
        it?.getContentIfNotHandled()?.let { responseStatus ->
            if (responseStatus.statusCode.equals(RESPONSE_STATUS_CODE)) {
                requireActivity().toastMessageOtp(responseStatus.statusMessage.toString())
                notificationSettingsViewModel.getDeviceList()
            }else{
                if(responseStatus.statusCode.equals(RESPONSE_STATUS_CODE_DEVICE_OVERRIDING)){
                    showDeviceOverridingAlert(requireContext() ,getString(R.string.alert_overriding_title) ,
                        responseStatus.errorModel?.dtoErrorMsg.toString()
                    )
                }
            }
        }
    })

And here is the add click of the button:

fun invokeAddDeviceCall(isOverride: Boolean){
    val isNotificationEnabled = isNotificationEnabled(requireContext())
    isNotificationEnabled?.let {
        if (it) {
            //Add the device
            if ((viewModel as NotificationSettingsViewModel).getTotalDeviceCount() >= 5) {
                /***Max device reached***/
                showMaxDeviceLimitDialog(requireContext())
            } else {
                (viewModel as NotificationSettingsViewModel).onClickAddNewDevice(requireContext() , isOverride)
            }
        } else {
            enableNotificationAlert(requireContext())
        }
    }
}