Now, we are going to use a MainViewModel for updating the UI. The module is a collection of dependencies we are going to provide to the application. Now, we will add the dependencies for Retrofit and Kotlin-Coroutines in the app's build.gradle like. A pragmatic lightweight dependency injection framework for Kotlin developers. You put all the services that a module should provide in the module block. So, create a Kotlin data class Resource inside the same utils package and add the following code. Koin is a DSL, a lightweight container and a pragmatic API. Our package in the project will look like below: We need the enum to represent the UI State. Sneak Peek of Upcoming Books and Video Courses! Inside AppModule first, we will create the functions we want to provide as dependencies. Note that I am overriding the Application and Context classes because, these classes are not available in a unit test, so you have to override them with mock implementations. With this example above, you see that the test class implements KoinTest, and that is what gives you access to functions like get, inject, startKoin, getKoin, etc. To run the app successfully, we will add the required permissions like. Now, we are done providing the dependencies. For example: With Koin, setting up dependency injection is kind of a manual process, you essentially plug your services into the module graphs and those dependencies will later get resolved at runtime. Koin is a lightweight dependency injection framework, that uses Kotlin’s DSLs to lazily resolve your dependency graph at runtime. Here, we will provide the MainRepository instance by. You will need to add the following to your module-level build.gradle. To provide dependencies in ViewModel we will update the ViewModelModule like. Using get it will only provide the constructor whose instance is already been provided by Koin. It is one of the easy DI frameworks which doesn't require a steep learning curve to get hold of it. This can be done in some ways similar to the factory defined above. For example: The first thing to note is, SomeActivity doesn’t implement KoinComponent but it has access to the Koin container, this is because Koin already provides extension functions for Android configuration-aware components, so you can access the Koin context with an Activity or the like. Now, we will create a package di -> module and inside it, we will create AppModule, ViewModelModule, and RepositoryModule. This block is the container in which you will map out the services that this module provides, like in the code above, the data module provides a SharedPerferenceManager, a ContactManager, and a ContactServerManager. Kotlin 1.3, Android 4.1, Android Studio 3 Dependency Injection (DI) is one of those “new” concepts that keeps showing up in every blog post on the Internet.
and inside the module, we will pass the single instance of all the functions we created like.

“Dependency Injection in Android With Dagger2” “Hilt — A New Dependency Injection Library for Android” To learn more about Kotlin , read Advanced Programming With Kotlin series: Here is an example: The createOnStart flag can be very helpful when you have some service(s) that might take time to resolve at runtime, it tells Koin to resolve those dependencies immediately when started and thus it could reduce or prevent lags when the user moves through the app. Now, in the project what we will do is, we will do an API call and show a list of users.
This is similar to Dagger-2 @Scope annotation. It will have files like. Now, to create the file as a supported module for Koin, we will pass the functions as singleton instance to the module. We are naming that as Resource. Of course, you need to write tests, unit tests should have been the first thing I talked about but out of the convention, I put it last. If you are unfamiliar with the concept of dependency injection, you can read this article to understand what it is and how it is used. With the scope definition, you must specify the scope_id which is just a unique string representing the scope definition. In fact, the idea is not new, but a notion that gets revisited from time to time. In this blog, we are going to learn about Koin, a new dependency injection framework for Android Developers. {, val sampleModule = module("org.sample") { ... }, val injectedService: SampleSecondService by, val service: SampleService = get("SampleService"), // or eagerly create an entire module definition, // or you can mark the entire module definition as override, // you can load the test modules at run-time, // add test library to your module gradle file, Learning Android Development in 2018 [Beginner’s Edition], Google just terminated our start-up Google Play Publisher Account on Christmas day, A Beginner’s Guide to Setting up OpenCV Android Library on Android Studio, Android Networking in 2019 — Retrofit with Kotlin’s Coroutines, REST API on Android Made Simple or: How I Learned to Stop Worrying and Love the RxJava, Android Tools Attributes — Hidden Gems of Android Studio. But for the second definition, you must use the same name specified during bean definition when trying to retrieve the dependency. We have been using the Dependency Injection framework quite a few times like Dagger in our project. Since google provided us with architecture components, it has been a ride with the MVVM architecture. Understanding how to arrange your code to accomplish what you wanted, took a lot of research and re-explaining. Dagger is a popular dependency injection library for Java, Kotlin, and Android that is maintained by Google. It tells Koin to retain the instance and provide that single instance wherever needed. There are a couple of things here to take note of, the first is the version of the factory function that just takes the generic parameter, that is an experimental feature that simplifies the code-block version. And for ApiHelper, we would need the ApiHelperImpl part to be provided which is the extension for ApiHelper. Now, let's break the further tasks in steps. I say this because Dagger-2 had complicated the concept for me when I came into android. There are just two things you need to do first and then you can start testing right away. You could find my sample project on the GitHub. For the project, we are going to follow a basic version of MVVM. Now our project is ready with dependencies. We are also passing all the modules which we created in the di/modules package. Now, inside the MainRepository, we will update the code like. Dagger facilitates using DI in your app by creating and managing the graph of dependencies for you. To provide the ApiHelperImpl in the module, we will update the code and create a single instance like. Note: Instead of using the eager resolution, get, you could also use the lazy resolution with the inject function. While working with Koin, there are few terminologies we need to understand before getting started. I am going to walk you through the key concepts of Koin, how to setup DI for Android and also Unit tests/Automated UI tests. We will update the file like. the protocol for the request (HTTP or HTTPS). First get the library into your project. Written in pure Kotlin using functional resolution only: no proxy, no code generation, no reflection! and we will update the Manifest file like.

That’s the feature of the bind function. the rest of the base URL for the Wikipedia API (wikipedia.org/w/api.php). import com.your.domain.ClassName). If you are not familiar with why we need a dependency injection framework in our project, click here.