Error Handling with RecyclerView when we get empty or null response from BE.

 Error Handling Best Practices 

When there is no network when it is launched, it shows a blank screen -> this is not a good user experience in app. 

So we will see some of the basics of error handling. 

• If network is not available -> we show connection error icon
• If fetching the data -> we show the loading animation 

We need to create a LiveData in ViewModel to represent the status of our web request. 

enum class MyApiStatus { LOADING, ERROR, DONE }

// The external immutable LiveData for the request status
val status: LiveData<MyApiStatus>
    get() = _status

coroutineScope.launch {
    
    var getPropertiesDeferred =  MyApi.retrofitService.getProperties()
    // surround the Retrofit code with try/catch, and set _response appropriately
    try {
        _status.value = MyApiStatus.LOADING
        var listResult = getPropertiesDeferred.await()
        _status.value = MyApiStatus.DONE
        _properties.value = listResult
        _response.value = "Success: ${listResult?.size} My properties retrieved"
    }catch (t: Throwable){
        _response.value = "Failure:" + t.message
        _status.value = MyApiStatus.ERROR
        _properties.value = emptyList()
    }
}

@BindingAdapter("myApiStatus")
fun bindStatus(statusImageView: ImageView, status: MyApiStatus?) {
    when (status) {
        MyApiStatus.LOADING -> {
            statusImageView.visibility = View.VISIBLE
            statusImageView.setImageResource(R.drawable.loading_animation)
        }
        MyApiStatus.ERROR -> {
            statusImageView.visibility = View.VISIBLE
            statusImageView.setImageResource(R.drawable.ic_connection_error)
        }
        MyApiStatus.DONE -> {
            statusImageView.visibility = View.GONE
        }
    }
}

<ImageView
    android:id="@+id/status_image"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    app:myApiStatus="@{viewModel.status}" />