不确定如何在 Room Android 中将 Cursor 转换为此方法的 return 类型？

Question

我在构建应用程序时遇到以下错误

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class

@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)

这就是我的道Class

@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>)
}

谁能帮忙看看这是什么问题？

Answer 1

当你声明 Dao 的函数时，returns Flow 该函数不应该是可暂停的。 Please see docs.

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>)
}

并为 Instant 类型添加 type converter，如果尚未添加，则在 NotificationEntity 中使用。