kotlin - 房间用构造函数生成ID

Question

我是usind Room DB，我有一个需要生成ID的类:

@Entity
data class TaskEntity(
@PrimaryKey(autoGenerate = true) var uid: Long?,
@ColumnInfo(name = "title") var title: String?,
@ColumnInfo(name = "start") var startTime: Long?,
@ColumnInfo(name = "duration") var duration: Long?,
): Serializable {

 constructor(
) : this(null, "", 0, 0)
}

在 Activity 中，我将在运行时初始化calss并设置参数:

var task: TaskEntity
task = TaskEntity()
task.name = cal.name
.... 

道课:

@Dao
interface TasksDao {
@Query("SELECT * FROM  taskentity ORDER BY startTime ASC")
fun getAllTasks(): List<TaskEntity>

@Insert
fun insert(item: TaskEntity)

@Delete
fun delete(item: TaskEntity)

@Update
fun update(item: TaskEntity)

}

但是ID始终像在构造函数中一样为null。我已经在一些文档中看到过，如果它的null将自动生成。我想念什么？

Answer 1

您已经手动创建了TaskEntity对象，因此uid为null
带有主键和null标志的整数字段也允许0或autoGenerate初始值
所以我想写更好

@PrimaryKey(autoGenerate = true) var uid: Long,
// ...
) : this(0L, "", 0, 0)