Android room typeconverterの問題

Question

私は部屋の永続性ライブラリ経由でデータベースに値を保存しようとしています。私のSettingsValueModelConverterが間違っているsomethingsがありません。どのように私はSettingsKeyContractオブジェクトを最も良い方法で保存することができますか？

Logcat：

SettingsModel 

Error:(14, 1) error: Cannot figure out how to save this field into database. You can consider adding a type converter for it. 

コード：あなたのデータベースを定義します

object SETTING_CONS{ 
    const val TABLE = "Content_Setting" 
    const val ID = "uid" 
    const val KEY = "key" 
    const val VALUE = "value" 
} 

class SettingsValueModel(var value: SettingsKeyContract) 
class SettingsValueModelConverter { 

    @TypeConverter 
    fun fromString(value: String): SettingsKeyContract = Gson().fromJson(value, object : TypeToken<SettingsKeyContract>() {}.type) 

    @TypeConverter 
    fun fromModel(value: SettingsKeyContract): String = Gson().toJson(value) 

} 

@Entity(tableName = SETTING_CONS.TABLE) 
class SettingsModel(@ColumnInfo(name = SETTING_CONS.KEY) @SETTINGS var key: String, 
        @ColumnInfo(name = SETTING_CONS.VALUE) var value: SettingsValueModel) { 

    @ColumnInfo(name = SETTING_CONS.ID) 
    @PrimaryKey(autoGenerate = true) 
    var uid: Int = 0 

} 

@Dao 
interface SettingsDao { 

    @Query("SELECT * FROM ${SETTING_CONS.TABLE} WHERE ${SETTING_CONS.ID} = :key") 
    fun get(@SETTINGS key: String): LiveData<SettingsModel> 

    @get:Query("SELECT * FROM ${SETTING_CONS.TABLE}") 
    val all: LiveData<MutableList<SettingsModel>> 

    @Insert(onConflict = OnConflictStrategy.REPLACE) 
    fun insert(model: SettingsModel): Long 

    @Insert(onConflict = OnConflictStrategy.REPLACE) 
    fun insertAll(vararg models: SettingsModel): LongArray 

    @Query("DELETE FROM ${SETTING_CONS.TABLE} WHERE ${SETTING_CONS.KEY} = :key") 
    fun delete(@SETTINGS key: String) 

    @Query("DELETE FROM ${SETTING_CONS.TABLE}") 
    fun clear() 

} 


interface SettingsKeyContract { val key: String } 
interface TypeSettingsKeyContract<out T : Any> : SettingsKeyContract { val default: T } 

sealed class SETTING(override val key: String) : SettingsKeyContract { 

    object FIRST_LAUNCH_DATE : SETTING("first_launch_date"), TypeSettingsKeyContract<Long> { override val default = 0L } 

} 

Answer 1

？ 使用するコンバーターを指定するオプションが必要です。

@Database(entities = arrayOf(SettingsModel::class) , version = 1, exportSchema = false) 
@TypeConverters(SettingsValueModelConverter::class) 
abstract class AppDatabase: RoomDatabase() { 
    abstract fun SettingsDao(): SettingsDao 
}