相同类型的嵌套关系

Question

根据the documentation关系只能引用Pojo类。如何定义相同类型的嵌套依赖项？

@Entity(tableName = "humans")
data class Human {

   @Relation
   val children:List<Human>

}

Answer 1

根据this中型博客文章，您可以使用类型转换器将列表转换为字符串，反之亦然。

class HumanTypeConverters {

    private var gson = Gson()

    @TypeConverter
    fun stringToHumanObjectList(data: String?): List<Human> {
        if (data == null) {
            return Collections.emptyList()
        }
        return gson.fromJson(data, object : TypeToken<List<Human>>() {}.type)
    }

    @TypeConverter
    fun humanObjectListToString(humanObjects: List<Human>): String = gson.toJson(humanObjects)
}

并按如下所示添加此注释

@Database(entities = [Human::class], version = 1)
@TypeConverters(HumanTypeConverters::class)
abstract class HumanDatabase : RoomDatabase() {
    ...
}