room android

DataHolder.kt

@Entity(tableName = "rss_feeds")
class DataHolder(@PrimaryKey(autoGenerate = false)
                 @ColumnInfo(name = "link")
                 var link: String,
                 @ColumnInfo(name = "title")
                 var title: String,
                 @ColumnInfo(name = "date")
                 var date: Long,
                 @ColumnInfo(name = "img_url")
                 var imgUrl: String = "",
                 @ColumnInfo(name = "bookmarked")
                 var bookmarked: Boolean = false,
                 @ColumnInfo(name = "was_read")
                 var wasRead: Boolean = false)

@Dao
interface RssItemsDao {

    @Insert(onConflict = OnConflictStrategy.IGNORE)
    fun saveAll(list: List<DataHolder>)

    @Query("SELECT * from rss_feeds WHERE link = :link LIMIT 1")
    fun get(link:String): DataHolder

    @Query("SELECT * from rss_feeds")
    fun getAll(): List<DataHolder>

    @Query("SELECT * from rss_feeds WHERE bookmarked='true'")
    fun getBookmarked(): List<DataHolder>

    @Update
    fun updateRssItems(rssItems: List<DataHolder>):Int

    @Update
    fun updateRssItem(rssItem: DataHolder):Int

    @Query("DELETE from rss_feeds")
    fun deleteAll()
}


@Database(entities = [(DataHolder::class)], version = 1)
abstract class RssDataBase : RoomDatabase() {

    abstract fun rssDataDao(): RssItemsDao

    companion object {
        private var INSTANCE: RssDataBase? = null

        fun getInstance(context: Context): RssDataBase {
            if (INSTANCE == null) {
                synchronized(RssDataBase::class) {
                    INSTANCE = Room.databaseBuilder(context.applicationContext,
                                                    RssDataBase::class.java,
                                                    "rss.db").build()
                }
            }
            return INSTANCE!!
        }

        fun destroyInstance() {
            INSTANCE = null
        }
    }
}

// Usage:
RssDataBase.getInstance(context).rssDataDao().<method_name>

sdfd.gradle

dependencies {
    def room_version = "1.1.0" // or, for latest rc, use "1.1.1-rc1"

    implementation "android.arch.persistence.room:runtime:$room_version"
    annotationProcessor "android.arch.persistence.room:compiler:$room_version"

    // optional - RxJava support for Room
    implementation "android.arch.persistence.room:rxjava2:$room_version"

    // optional - Guava support for Room, including Optional and ListenableFuture
    implementation "android.arch.persistence.room:guava:$room_version"

    // Test helpers
    testImplementation "android.arch.persistence.room:testing:$room_version"
}