Retrofit2 LiveData Call Adapter

Get a LiveData responses from Retrofit.

@GET("posts/{id}")
fun getPost(@Path("id") postId: Int): LiveData<Resource<Post>>

A Retrofit2 Call Adapter for Android Architecture Components' LiveData. Works with Blueprint.

Installation with Gradle

This library is distributed through Jitpack. To install it:

Add this line in the repositories section of your project's build.gradle file:

allprojects {
  repositories {
    maven { url "https://jitpack.io" } // this line
  }
}

And this line in the dependencies of your module's build.gradle file:

dependencies {
  implementation "com.github.gianlucalimbi:retrofit2-livedata-adapter:1.0.0" // this line
}

Usage

When creating a Retrofit instance, just add the adapter using the addCallAdapterFactory() function.

Retrofit.Builder()
    .baseUrl(baseUrl)
    .addConverterFactory(converterFactory)
    .addCallAdapterFactory(LiveDataCallAdapterFactory()) // this line
    .client(okHttpClient)
    .build()

You are now good to go, you can use LiveData<Resource<AnyClass>> in your retrofit service interface, like this:

interface ApiService {

  @GET("posts")
  fun getPosts(): LiveData<Resource<List<Post>>>

  @GET("posts/{id}")
  fun getPost(@Path("id") postId: Int): LiveData<Resource<Post>>

}

Blueprint

This call adapter uses Blueprint's Resource class. You can check the Blueprint GitHub page for more documentation.

Blueprint also comes with a handy ResourceObserver class that you can use with this adapter.

val liveData = api.getPost(postId)
liveData.observe(lifecycleOwner, resourceObserver {

  onSuccess { data ->
    // data: Post -> the data returned from retrofit
  }

  onError { error ->
    // error: Exception -> an instance of HttpException if the API call failed (status >= 400), another Exception otherwise
  }

  onLoading { data ->
    // data: Post? -> always null
  }

  onChanged { resource ->
    // resource: Resource<Post>? -> the raw resource contained in the LiveData
  }

})