类型转换器无法弄清楚如何将此字段保存到数据库中

Question

我在实现 Room 的类型转换器时出错。

错误：无法弄清楚如何将此字段保存到数据库中。您可以考虑为其添加类型转换器。private java.util.List<? extends java.util.Map<java.lang.String, mypage.profile.entity.OtherServiceEntity>> otherServices;

这是我的实现， 首先像下面这样配置实体，因为 POJO 包含地图列表 我像这样实现了房间的类型转换器

object OtherServicesTypeConverter {
private val gson = Gson()
@TypeConverter
@JvmStatic
fun stringToList(data: String?): List<Map<String, OtherServiceEntity>> {
if (data == null) {
return Collections.emptyList()
}
val listType = object : TypeToken<List<Map<String, OtherServiceEntity>>>() {
}.type
return gson.fromJson<List<Map<String, OtherServiceEntity>>>(data, listType)
}
@TypeConverter
@JvmStatic
fun listToString(objects: List<Map<String, OtherService>>): String {
return gson.toJson(objects)
}
}

然后在实体内部使用注释，以及如下所示的数据库

@Entity(tableName = "ProfileEntities")
data class ProfileEntity(
@PrimaryKey
@SerializedName("masterId") var masterId: Long = 0,
@SerializedName("nickname") var nickname: String = "",
@TypeConverters(OtherServicesTypeConverter::class)
@SerializedName("otherServices") var otherServices: List<Map<String, OtherServiceEntity>>,
@Embedded
@SerializedName("images") var images: ProfileImagesEntity = ProfileImagesEntity(),
@SerializedName("updatedAt") var updatedAt: String = ""
)

@Database(entities = [ArticleFeatureEntity::class, ProfileEntity::class], version = 3)
@TypeConverters(DataTypeConverter::class, ProfileTypeConverter::class, OtherServicesTypeConverter::class)
abstract class AppDatabase : RoomDatabase() {
abstract fun profileDao(): ProfileDao
// Code here

}

请帮忙支持我，谢谢！

Answer 1

最后，我认识到 Room 需要在类型转换器实现中进行一些特殊的更改(更改为ArrayList<HashMap<String, OtherServiceEntity>>(。不过，不知道这是一个功能或错误，因为其他情况我仍然可以使用 List 作为类型。这是我所做的细节，现在我能够运行它

@Entity(tableName = "ProfileEntities")
data class ProfileEntity(
@TypeConverters(ProfileTypeConverter::class)
@SerializedName("details") var details: List<ProfileDetailEntity> = listOf(),
@Embedded
@SerializedName("images") var images: ProfileImagesEntity = ProfileImagesEntity(),
@PrimaryKey
@SerializedName("masterId") var masterId: Long = 0,
@TypeConverters(OtherServicesTypeConverter::class)
@SerializedName("otherServices") var otherServices: ArrayList<HashMap<String, OtherServiceEntity>> = arrayListOf(),
@SerializedName("updatedAt") var updatedAt: String = ""
)

以及转换器的实施

class ProfileTypeConverter {
private val gson = Gson()
@TypeConverter
fun stringToList(data: String?): List<ProfileDetailEntity> {
if (data == null) {
return Collections.emptyList()
}
val listType = object : TypeToken<List<ProfileDetailEntity>>() {
}.type
return gson.fromJson<List<ProfileDetailEntity>>(data, listType)
}
@TypeConverter
fun listToString(someObjects: List<ProfileDetailEntity>): String {
return gson.toJson(someObjects)
}
}
class OtherServicesTypeConverter {
private val gson = Gson()
@TypeConverter
fun stringToList(data: String?): ArrayList<HashMap<String, OtherServiceEntity>> {
if (data == null) {
return ArrayList()
}
val listType = object : TypeToken<ArrayList<HashMap<String, OtherServiceEntity>>>() {
}.type
return gson.fromJson<ArrayList<HashMap<String, OtherServiceEntity>>>(data, listType)
}
@TypeConverter
fun listToString(objects: ArrayList<HashMap<String, OtherServiceEntity>>): String {
return gson.toJson(objects)
}
}

祝您编码愉快！