SomeViewModel example

SomeViewModel.kt

sealed class ContentState {
    object Hidden : ContentState()
    data class Shown(val data: String) : ContentState()
}

class SomeViewModel(
    private val someInteractor: SomeInteractor,
    private val dispatchersProvider: DispatchersProvider
) : ViewModel() {

    private val isLoaderViewVisibleStateFlow = MutableStateFlow(false)
    private val isErrorViewVisibleStateFlow = MutableStateFlow(false)
    private val contentStateStateFlow = MutableStateFlow<ContentState>(ContentState.Hidden)

    init {
        loadInitialData()
    }
    
    fun onRetryButtonClicked() {
        loadInitialData()
    }

    private fun loadInitialData() = viewModelScope.launch(dispatchersProvider.io) {
        showLoaderState()
        // Another error handling strategy could be used. It's not important for the article.
        try {
            val data = someInteractor.doSomething()
            showContentState(data)
        } catch (throwable: Throwable) {
            showErrorState()
        }
    }

    private fun showContentState(data: String) {
        isErrorViewVisibleStateFlow.value = false
        isLoaderViewVisibleStateFlow.value = false
        contentStateStateFlow.value = ContentState.Shown(data)
    }

    private fun showErrorState() {
        isLoaderViewVisibleStateFlow.value = false
        isErrorViewVisibleStateFlow.value = true
        contentStateStateFlow.value = ContentState.Hidden
    }

    private fun showLoaderState() {
        isErrorViewVisibleStateFlow.value = false
        isLoaderViewVisibleStateFlow.value = true
        contentStateStateFlow.value = ContentState.Hidden
    }

    fun getLoaderState(): StateFlow<Boolean> = isLoaderViewVisibleStateFlow
    fun getErrorState(): StateFlow<Boolean> = isErrorViewVisibleStateFlow
    fun getContentState(): StateFlow<ContentState> = contentStateStateFlow
}