PostApiServiceDao.kt

interface PostApiService {
    @GET("/feed")
    fun getFeed(): Single<Response<List<Post>>>
}

@Dao
interface PostDao {
    @Insert(onConflict = OnConflictStrategy.IGNORE)
    fun insert(post: Post): Long

    @Update(onConflict = OnConflictStrategy.REPLACE)
    fun update(post: Post)

    @Transaction
    fun upsert(post: Post) {
        if (-1L == insert(post))
            update(post)
    }

    @Query("SELECT * FROM `post`")
    fun getPostList(): Observable<List<Post>>
}