android - 如何通过自定义列表在房间中创建TypeConverter？

Question

我做了一个TypeConverter，但出现错误

Unable to create converter for class .models.lastanime.EpisodesEntityfor method EpisodesApi.getEpisodes

我不能完全理解如何制作TypeConverter，我已经做到了，我知道实现位置正确，因为我在编译中没有问题，但是由于出现错误而无法加载数据，看来它没有保存在房间数据库中

TYPE CONVERTER

class ListStringConverter {

    @TypeConverter
    fun fromString(value: String?): List<ServerEntity> {
        val listType = object :
            TypeToken<List<ServerEntity?>?>() {}.type
        return Gson()
            .fromJson<List<ServerEntity>>(value, listType)
    }

    @TypeConverter
    fun listToString(list: List<ServerEntity?>?): String {
        val gson = Gson()
        return gson.toJson(list)
    }

}

模型主题实体

data class EpisodesEntity(
@SerializedName("episodes")
val episodes: List<EpisodeEntity>

)

模型典范实体

@Entity
data class EpisodeEntity(

    @PrimaryKey(autoGenerate = true)
    val id: Int,

    @SerializedName("poster")
    @ColumnInfo(name = "episode")
    val episode: Int?,

    @SerializedName("poster")
    @ColumnInfo(name = "poster")
    val poster: String?,

    @SerializedName("servers")
    @ColumnInfo(name = "servers")
    val servers: List<ServerEntity>?,

    @SerializedName("title")
    @ColumnInfo(name = "title")
    val title: String?

)

除了所有模型外，“服务器”列表还使我难以将其插入房间

@SerializedName("servers")
    @ColumnInfo(name = "servers")
    val servers: List<ServerEntity>?,

API存储库

interface LastEpisodesRepository {

fun lastEpisodes(): Flow<Either<Failure, List<Episode>>>

class Network(
    private val networkHandler: NetworkHandler,
    private val service: LastEpisodesService,
    private val local: EpisodeLocal
) : LastEpisodesRepository {

    val preferences by lazy { SharedPrefsHelpers() }

    override fun lastEpisodes(): Flow<Either<Failure, List<Episode>>> =
        flow {

            val days = local.getEpisodes()
            val time = preferences.getLong(LocalShared.LastAnimes.lastepisodes, 0L)

            if (days.isNullOrEmpty() || time == 0L || isFetchCurrentNeeded(time)) {
                emit(getRemoteDay())
            } else {
                emit(Either.Right(local.getEpisodes().map { it.toEpisode() }))
            }
        }.catch {
            emit(Either.Left(Failure.CustomError(ServiceKOs.DATABASE_ACCESS_ERROR, "DB Error")))
        }.flowOn(Dispatchers.IO)


    private fun getRemoteEpisode(): Either<Failure, List<Episode>> =
        when (networkHandler.isConnected) {
            true -> request(
                service.getEpisodes(),
                { episodeEntity ->

                    val episodeList: List<EpisodeEntity> = episodeEntity.episodes

                    preferences.saveLong(LocalShared.LastAnimes.lastepisodes, Date().time)

                    addAllEpisodes(episodeList)
                    episodeList.map { it.toEpisode() }

                },
                EpisodesEntity(emptyList())
            )
            false, null -> Either.Left(Failure.NetworkConnection())
        }

    private fun addAllEpisodes(episodes: List<EpisodeEntity>) {
        for (episode in episodes) {
            local.addEpisodes(episode)
        }
    }

}

Room是从本地变量进行的调用，应用程序检查是否有下载的数据，如果没有下载的数据，它将调用服务，返回数据，同时将其保存在Room数据库中。

Answer 1

您不能有一个实体持有另一个实体的List。您需要定义a one-to-many relation between them。