kotlin - 无法使用 Room ORM Kotlin 保存包含 List 的数据模型

Question

我在使用 Kotlin 的 Room ORM 时遇到问题。我的任务是能够保存和获取数据模型 RouteTemplateModel，其中包含 AddressModel 类型的地址列表和包含特定路线标题的 RouteModel 类的对象。这是我的代码:

地址模型.kt

@Entity(foreignKeys = arrayOf(
                        ForeignKey(entity = RouteModel::class,
                        parentColumns = arrayOf("routeId"),
                        childColumns = arrayOf("parentId"))))
data class AddressModel(
   @PrimaryKey(autoGenerate = true)
            var addressId: Long,
            var parentId: Long,
            var street: String,
            var house: String,
            var entrance: String,
            var title: String){
            constructor(): this(0, 0, "", "", "", "")         
}        

RouteModel.kt

@Entity
data class RouteModel(
    @PrimaryKey(autoGenerate = true)
    var routeId: Long,
    var title: String) {
    constructor() : this(0, "")
}

这是我的简单模型，我在 Room 的文档中发现，为了在模型之间创建关系，我需要使用 @ForeignKey和 @Relation
因此，使用文档和教程中的代码示例，我创建了 RouteTemplateModel包含 RouteModel 的对象和列表 AddressModels .这是类

RouteTemplateModel

class RouteTemplateModel{

    private var id: Long = 0

    @Embedded
    private var routeModel: RouteModel = RouteModel()

    @Relation(parentColumn = "routeId", entityColumn = "parentId")
    private var addressList: List<AddressModel> = listOf()

    constructor()

    constructor(id: Long, routeModel: RouteModel, title: String,
                addressList: List<AddressModel>){
        this.id = id
        this.routeModel = routeModel
        this.addressList = addressList
    }

    fun getId(): Long{
        return id
    }

    fun getRouteModel(): RouteModel{
        return routeModel
    }

    fun getAddressList(): List<AddressModel>{
        return addressList
    }

    fun setId(id: Long){
        this.id = id
    }

    fun setRouteModel(routeModel: RouteModel){
        this.routeModel = routeModel
    }

    fun setAddressList(addressList: List<AddressModel>){
        this.addressList = addressList
    }

}

那么有什么问题呢？我收到这样的错误:

Error:The columns returned by the query does not have the fields [id] in com.innotech.webcab3kotlin.model.RouteTemplateModel even though they are annotated as non-null or primitive. Columns returned by the query: [routeId,title]

和

Error:Type of the parameter must be a class annotated with @Entity or a collection/array of it.

这是一个真正的问题，因为如果我尝试修复第一个错误并在 RouteTemplateModel 中进行注释id 变量也返回此列，我需要将类注释为实体(就像在第二个错误中一样)，但是当我这样做时，我收到一个错误

Error:Entities cannot have relations.

这是 AppDatabase.kt

@Database(entities = arrayOf(RouteModel::class, AddressModel::class), version = 1)
abstract class AppDatabase : RoomDatabase() {

    abstract fun getRouteDao(): RouteDao
}

和 RouteDao.kt

@Dao
interface RouteDao {


    @Query("SELECT routeId, title FROM RouteModel")
    fun getAll(): List<RouteTemplateModel>

    @Insert
    fun insertAll(vararg models: RouteTemplateModel)

    @Delete
    fun delete(model: RouteTemplateModel)


}

这真是令人困惑。请帮我)

Answer 1

您的“parentId”列只能保存 long 值，将其类型设置为“Text”，然后创建一个从“List”到 String 的 TypeConverter，反之亦然以供引用，请查看 link .