动态查询房间数据库不支持LiveData吗？

Question

我读过这篇文章。

Room支持@RawQuery注释，以在运行时构造查询，例如代码A。

如果我使用代码B，当我完成它时，我会得到错误B。

似乎@RawQuery不支持返回LiveData，对吧？

代码A

interface DBVoiceDao{ 

   @RawQuery
   fun  runtimeQuery(sortQuery: SupportSQLiteQuery): List<MVoice>
    ...
}

代码B

interface DBVoiceDao{ 

   @RawQuery
   fun  runtimeQuery(sortQuery: SupportSQLiteQuery): LiveData<List<MVoice>>
    ...
}

错误B

Schema export directory is not provided to the annotation processor so we cannot export the schema. You can either provide `room.schemaLocation` annotation processor argument OR set exportSchema to false.
public abstract class DBVoiceDatabase extends androidx.room.RoomDatabase {
                ^[WARN] Incremental annotation processing requested, but support is disabled because the following processors are not incremental: androidx.room.RoomProcessor (DYNAMIC).                                    

Answer 1

它确实支持它，但是您必须指定观察到的实体，如以下https://developer.android.com/reference/androidx/room/RawQuery示例所述：

kotlin prettyprint-override">@Dao
 interface RawDao {
   @RawQuery(observedEntities = Song.class)
   LiveData<List<Song>> getSongs(SupportSQLiteQuery query);
 }