CODEWITHSUNDEEP
androidkotlinandroid-room
Kyle
Kyle

Reputation: 154

Android Room - Type converter not working in entity field scope

I've trying to add type converter to my entity, but I found the it only work at database, dao and entity scope, not in entity field scope.

For example : when I add type converter in Entity scope like this, it works fine.

@Entity(tableName = "chat_history")
@TypeConverters(ChatEntityConverter::class)
class ChatHistoryEntity (
    @PrimaryKey
    @NonNull
    @ColumnInfo(name = "history_id") val HID: Long?,
    @ColumnInfo(name = "history_name") var pairedName: String?,
    @ColumnInfo(name = "history_last_message") var lastMessage: String?,
    @ColumnInfo(name = "history_last_date")
    var lastDate: Date?
)

But if I move it into Entity field scope, it fail to compile.

@Entity(tableName = "chat_history")
class ChatHistoryEntity (
    @PrimaryKey
    @NonNull
    @ColumnInfo(name = "history_id") val HID: Long?,
    @ColumnInfo(name = "history_name") var pairedName: String?,
    @ColumnInfo(name = "history_last_message") var lastMessage: String?,
    @TypeConverters(ChatEntityConverter::class)
    @ColumnInfo(name = "history_last_date")
    var lastDate: Date?
)

It shows the error message like this :

error: Cannot figure out how to save this field into database.

My converter is :

class ChatEntityConverter {
    @TypeConverter
    fun fromTimeStamp(date: Long?): Date? {
        return when(date) {
            null -> null
            else -> Date(date)
        }
    }

    @TypeConverter
    fun dateToTimeStamp(date: Date?): Long? {
        return when(date) {
            null -> null
            else -> date.time
        }
    }
}

Since it also convert long type to date type, I don't want it to work on Entity scope. Only in date type field scope. But I just couldn't put it there and compile it.

Upvotes: 2

Views: 862

Answers (1)

CommonsWare
CommonsWare

Reputation: 1006869

@TypeConverters works on a field. You are using Kotlin, so you are working more directly with properties. To apply the annotation to the backing field, use @field:TypeConverters instead of @TypeConverters.

Upvotes: 6

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