不确定如何在 Room Android 中将 Cursor 转换为该方法的返回类型？

Question

构建应用程序时出现以下错误

Not sure how to convert a Cursor to this method's return type (kotlinx.coroutines.flow.Flow<? extends java.util.List<com.notification.NotificationEntity>>)

这是我的实体类

@Entity
internal data class NotificationEntity(
@PrimaryKey @ColumnInfo(name = "notification_id") val notificationId: String,
val title: String,
val body: String?,
@ColumnInfo(name = "is_actionable") val isActionable: Boolean,
@ColumnInfo(name = "created_at") val createdAt: Instant,
@ColumnInfo(name = "is_read") val isRead: Boolean = false)

这是我的道课

@Dao
internal interface NotificationDao {

@Query("SELECT * FROM NotificationEntity ORDER BY created_at ASC")
suspend fun getAllNotifications(): Flow<List<NotificationEntity>>

@Insert(onConflict = OnConflictStrategy.REPLACE)
suspend fun saveNotification(notifications: List<NotificationEntity>)
}

有人可以帮助这里有什么问题吗？

Answer 1

当您声明返回Flow的 Dao 函数时，该函数不应是可挂起的。 请参阅文档。

将您的代码更改为：

@Dao
internal interface NotificationDao {

@Query("SELECT * FROM NotificationEntity ORDER BY created_at ASC")
fun getAllNotifications(): Flow<List<NotificationEntity>>

@Insert(onConflict = OnConflictStrategy.REPLACE)
suspend fun saveNotification(notifications: List<NotificationEntity>)
}

如果尚未添加，则为 NotificationEntity 中使用的Instant类型添加类型转换器。