Sample Room DB with Rx

RepoTest.kt

class RepoTest(private val testDao:TestDao){ //inject dao using Koin
  fun insertTest(test:Test) : Single<Resource<String>> = testDao.insertTest(test)
  .             .subscribeOn(Schedulers.io())
                .map<Resource<String>> { t -> Resource.Success(t.toString()) } // convert primary key value to String
                .onErrorReturn { Resource.Failure(it) }
                .observeOn(AndroidSchedulers.mainThread())
}

Resource.kt

sealed class Resource<out T> {
    data class Success<out T>(val data: T?) : Resource<T>()
    data class Failure<out T>(val throwable: Throwable) : Resource<T>()
}

TestDao.kt

@Dao
interface TestDao{

  @Insert(onConflict = OnConflictStrategy.REPLACE) // replace data on conflict
    fun insertTest(test: Test): Single<Long> // return primary key
}

TestViewModel.kt

class TestViewModel(private val repo:RepoTest) { // inject repo using Koin
  fun insertTest(test:Test){
   repo.insertTest(test).subscribe(
                    {
                        when (it) {
                            is Resource.Success -> {
                                e { "success save data with primary key : ${it.data}" }
                            }
                            is Resource.Failure -> {
                                e (it.throwable)
                            }
                            else -> throw IllegalStateException("State not known or implemented.")
                        }
                    }, {
                it.printStackTrace()
            })
  }
}