Flower is a Kotlin multi-platform (originally, Android) library that makes networking and database caching easy. It enables developers to fetch network resources and use them as is OR combine them with local database at single place with fault-tolerant architecture.   ## Special thanks A special thanks to [JetBrains](https://www.jetbrains.com/community/opensource) for sponsoring the [tools](https://www.jetbrains.com/lp/intellij-frameworks) required to develop this project.

## Why Flower? - It helps you to handle different states (`Loading`, `Success`, `EmptySuccess`, `Error`) of resources efficiently. - It helps you to use local data in case of network unavailability. - It provides a fluid app experience by not blocking the `main thread` when accessing network/database resources. Flower is recognised by [Google Dev Library](https://devlibrary.withgoogle.com/products/android/repos/hadiyarajesh-flower), a showcase of open-source projects. ## Installation Flower is primarily available in two modules, one for **Ktorfit** and the other for **Retrofit**. If you want to handle networking yourself, you can also use the **core** module. `$flowerVersion=3.1.0`
`$ktorFitVersion=1.0.0-beta16`
`$retrofitVersion=2.9.0` ### Ktorfit This is a multiplatform module. It is suitable for use in Kotlin multiplatform projects, Android (Apps/Libraries), the JVM in general, Kotlin-JS, and so on... It uses and provides [Ktorfit](https://github.com/Foso/Ktorfit) and you must use KSP in your project. Apply the KSP Plugin to your project: ```gradle plugins { id("com.google.devtools.ksp") version "1.7.10-1.0.6" } ``` **Multiplatform example** ```gradle dependencies { implementation("io.github.hadiyarajesh.flower-ktorfit:flower-ktorfit:$flowerVersion") add("kspCommonMainMetadata", "de.jensklingenberg.ktorfit:ktorfit-ksp:$ktorFitVersion") add("kspJvm", "de.jensklingenberg.ktorfit:ktorfit-ksp:$ktorFitVersion") add("kspAndroid", "de.jensklingenberg.ktorfit:ktorfit-ksp:$ktorFitVersion") add("kspIosX64", "de.jensklingenberg.ktorfit:ktorfit-ksp:$ktorFitVersion") add("kspJs", "de.jensklingenberg.ktorfit:ktorfit-ksp:$ktorFitVersion") add("kspIosSimulatorArm64", "de.jensklingenberg.ktorfit:ktorfit-ksp:$ktorFitVersion") } ``` **Android example** ```gradle dependencies { implementation("io.github.hadiyarajesh.flower-ktorfit:flower-ktorfit:$flowerVersion") //Ktorfit library implementation("de.jensklingenberg.ktorfit:ktorfit-lib:$ktorFitVersion") ksp("de.jensklingenberg.ktorfit:ktorfit-ksp:$ktorFitVersion") } ``` ### Retrofit This is an Android-only module, so it can only be used in Android Apps/Libs. ```gradle dependencies { implementation("io.github.hadiyarajesh.flower-retrofit:flower-retrofit:$flowerVersion") // Retrofit library implementation("com.squareup.retrofit2:retrofit:$retrofitVersion") } ``` ### Core This module only contains the _core code_ and allows you to handle the networking yourself. **We Highly recommend you to use either Ktorfit or Retrofit module. Only use this if you don't want to rely on Ktorfit or Retrofit.** ```gradle dependencies { implementation("io.github.hadiyarajesh:flower-core:$flowerVersion") } ``` ## Usage Assume you have a model class called `MyModel` that you are retrieving from the network. ```kotlin data class MyModel( val id: Long, val data: String ) ``` ### Prerequisite - If you want to save network response in a local database, your database caching system function must return a value of type `Flow`. **Android Room example:** ```kotlin @Dao interface MyDao { @Query("SELECT * FROM Data") fun getLocalData(): Flow } ``` - Return type of networking api function must be `ApiResponse` ( or `Flow>` if you're retrieving a flow of data from server) **Ktorfit/Retrofit example:** ```kotlin interface MyApi { @GET("data") suspend fun getRemoteData(): ApiResponse // OR @GET("data") fun getRemoteData(): Flow> } ```

#### 1. Add CallAdapterFactory/ResponseConverter in networking client **Ktorfit** Add `FlowerResponseConverter` as *ResponseConverter* in Ktorfit builder. ```kotlin Ktorfit.Builder() .baseUrl(BASE_URL) .httpClient(ktorClient) .responseConverter(FlowerResponseConverter()) .build() ``` **Retrofit** Add `FlowerCallAdapterFactory` as *CallAdapterFactory* in Retrofit builder ```kotlin Retrofit.Builder() .baseUrl(BASE_URL) .client(okHttpClient) .addCallAdapterFactory(FlowerCallAdapterFactory.create()) .build() ```

#### 2. Make network request (and save data) in Repository **2.1** If you want to fetch network resources and save into local database, use `dbBoundResource()` higher order function (or `dbBoundResourceFlow()` function if you're retrieving a flow of data from server). It takes following functions as parameters. - *fetchFromLocal* - A function to retrieve data from local database - *shouldMakeNetworkRequest* - Decides whether or not to make network request - *makeNetworkRequest* - A function to make network request - *processNetworkResponse* - A function to process network response (e.g., saving response headers before saving actual data) - *saveResponseData* - A function to save network response (`MyModel`) to local database - *onNetworkRequestFailed* - An action to perform when a network request fails ```kotlin fun getMyData(): Flow> { return dbBoundResources( fetchFromLocal = { myDao.getLocalData() }, shouldMakeNetworkRequest = { localData -> localData == null }, makeNetworkRequest = { myApi.getRemoteData() }, processNetworkResponse = { }, saveResponseData = { myDao.saveMyData(it) }, onNetworkRequestFailed { errorMessage, statusCode -> } ).flowOn(Dispatchers.IO) } ``` **OR** **2.2** If you only want to fetch network resources without saving it in local database, use `networkResource()` higher order function. (or `networkResourceFlow()` function if you're retrieving a flow of data from server) ```kotlin fun getMyData(): Flow> { return networkResource( makeNetworkRequest = { myApi.getRemoteData() }, onNetworkRequestFailed { errorMessage, statusCode -> } ).flowOn(Dispatchers.IO) } ```

#### 3. Collect `Flow` to observe different state of resources (`Loading`, `Success`, `Error`) In ViewModel ```kotlin // A model class to re-present UI state sealed class UiState { object Empty : UiState() data class Loading(val data: T?) : UiState() data class Success(val data: T & Any) : UiState() data class Error(val msg: String?) : UiState() } ``` ```kotlin private val _myData: MutableStateFlow> = MutableStateFlow(UiState.Empty) val myData: StateFlow> = _myData.asStateFlow() init { viewModelScope.launch { getMyData() } } suspend fun getMyData() = repository.getMyData().collect { response -> when (response.status) { is Resource.Status.Loading -> { val status = response.status as Resource.Status.Loading _myData.value = UiState.Loading(status.data) } is Resource.Status.Success -> { val status = response.status as Resource.Status.Success _myData.value = UiState.Success(status.data) } // EmptySuccess is for potentially body-less successful HTTP responses like 201, 204 is Resource.Status.EmptySuccess -> { _myData.value = UiState.Empty } is Resource.Status.Error -> { val status = response.status as Resource.Status.Error _myData.value = UiState.Error(status.message) } } } ```

#### 4. Observe data in Activity/Fragment/Composable function to drive UI changes ```kotlin lifecycleScope.launchWhenStarted { viewModel.myData.collect { data -> when (data) { is UiState.Loading -> { // Show loading } is UiState.Success -> { // Show success } is UiState.Error -> { // Show error } else -> {} } } } ``` ## Sample Two sample apps are provided in this repository 1. [XML View based app](https://github.com/hadiyarajesh/flower/tree/master/app) - It fetch random quote from remote api and save it to local database in order to display it on UI. 2. [Jetpack Compose based app](https://github.com/hadiyarajesh/flower/tree/master/compose-app) - It fetches unsplash images from [Picsum](https://picsum.photos) and display it on UI. ## License [Apache License 2.0](https://github.com/hadiyarajesh/flower/blob/master/LICENSE)