Question

我决定将kotlin与Room库一起使用，我真的遇到了很多问题而且厌倦了阅读参考并找到解决方案我的数据类：

@Entity
data class HistorySong(
        @PrimaryKey
        var SongId: Int =0,

        @ColumnInfo(name = "song_name")
        var songName: String="",

        @ColumnInfo(name = "song_artist")
        var songArtist: String="",

        @ColumnInfo(name = "song_link")
        var songLink: String="",

        @ColumnInfo(name = "image_path")
        var songImagePath: String="",

        @ColumnInfo(name="is_favoutire")
        var songisFavourite: Boolean= false
)

我的Dao课程：

@Dao
 interface HistorySongDao {

       @Delete
       fun deleteSong(historySongDao: HistorySongDao)

       @Insert(onConflict = OnConflictStrategy.REPLACE)
        fun insert(vararg historySongDao: HistorySongDao)

       @Query("SELECT * FROM HistorySong")
        fun loadAllSongs(): Array<HistorySong>


       @Query("SELECT * FROM HistorySong WHERE songId = :mId")
        fun findById(mId: Int): HistorySong

       @Query("SELECT * FROM HistorySong WHERE is_favoutire = :getFavourite ")
        fun getFavourite(getFavourite : Boolean) : Array<HistorySong>



       @Update
       fun updateUsers(vararg historySong: HistorySong)
}

数据库类：

@Database(entities = arrayOf(QueuedSong::class, HistorySongDao::class), version = 2)
abstract class AppDataBase : RoomDatabase() {
    abstract fun queuedSongDao(): QueuedSongDao
    abstract fun historySongDao(): HistorySongDao
}

QueuedSong工作得很好，但历史上的问题是：

e: F:\SmartStreamer\app\build\tmp\kapt3\stubs\debug\com\pro\smartstreamer\Database\QueuedDatabase\HistorySongDao.java:7: error: Entity class must be annotated with @Entity
public abstract interface HistorySongDao {
                ^
w: F:\SmartStreamer\app\build\tmp\kapt3\stubs\debug\com\pro\smartstreamer\Database\QueuedDatabase\AppDataBase.java:10: warning: Room cannot create an SQLite connection to verify the queries. Query verification will be disabled. Error: [SQLITE_ERROR] SQL error or missing database (near ")": syntax error)
public abstract class AppDataBase extends android.arch.persistence.room.RoomDatabase {
                ^
w: F:\SmartStreamer\app\build\tmp\kapt3\stubs\debug\com\pro\smartstreamer\Database\QueuedDatabase\HistorySong.java:10: warning: There are multiple good constructors and Room will pick the no-arg constructor. You can use the @Ignore annotation to eliminate unwanted constructors.
public final class HistorySong {
             ^
e: F:\SmartStreamer\app\build\tmp\kapt3\stubs\debug\com\pro\smartstreamer\Database\QueuedDatabase\HistorySongDao.java:15: error: Type of the parameter must be a class annotated with @Entity or a collection/array of it.
    com.pro.smartstreamer.Database.QueuedDatabase.HistorySongDao... historySongDao);
                                                                    ^
e: F:\SmartStreamer\app\build\tmp\kapt3\stubs\debug\com\pro\smartstreamer\Database\QueuedDatabase\HistorySongDao.java:11: error: Type of the parameter must be a class annotated with @Entity or a collection/array of it.
    com.pro.smartstreamer.Database.QueuedDatabase.HistorySongDao historySongDao);
                                                                 ^
e: F:\SmartStreamer\app\build\tmp\kapt3\stubs\debug\com\pro\smartstreamer\Database\QueuedDatabase\HistorySongDao.java:30: error: com.pro.smartstreamer.Database.QueuedDatabase.HistorySongDao is part of com.pro.smartstreamer.Database.QueuedDatabase.AppDataBase but this entity is not in the database. Maybe you forgot to add com.pro.smartstreamer.Database.QueuedDatabase.HistorySong to the entities section of the @Database?
    public abstract void updateUsers(@org.jetbrains.annotations.NotNull()

和：

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:kaptDebugKotlin'.
> Compilation error. See log for more details

我真的无法找到解决方案.. 提前致谢

Answer 1

正如它在第一条评论中所说，你试图插入和删除HistorySongDao对象而不是HistorySong，你的代码将成为：

@Dao
 interface HistorySongDao {

       @Delete
       fun deleteSong(vararg historySong: HistorySong)

       @Insert(onConflict = OnConflictStrategy.REPLACE)
        fun insert(vararg historySong: HistorySong)

       @Query("SELECT * FROM HistorySong")
        fun loadAllSongs(): Array<HistorySong>

       @Query("SELECT * FROM HistorySong WHERE songId = :mId")
        fun findById(mId: Int): HistorySong

       @Query("SELECT * FROM HistorySong WHERE is_favoutire = :getFavourite ")
        fun getFavourite(getFavourite : Boolean) : Array<HistorySong>

       @Update
       fun updateUsers(vararg historySong: HistorySong)
}

Answer 2

将数据库类更新为此

geom_ribbon

我将HistorySongDao.class更改为HistorySong.class

Answer 3

我通过更改@Database的参数（RoomDatabase类）解决了这个问题，但我没有意识到并将DAO放在应该是我的实体的位置。

就我而言：

@Database(entities = [WordDao::class],version = 1)

更改为：

@Database(entities = [WordEntity::class],version = 1)

因此，当有人遇到此错误时，也许应该不仅检查声明实体的位置，而且还要检查使用它的位置。

Answer 4

对我来说，这是一个不同的问题：[而不是{

我放了：

@Database(entities = [Sensor.class, Meter.class],version = 2)

代替：

@Database(entities ={Sensor.class, Meter.class}, version = 2)

Answer 5

您在数据库类中错误地使用了实体。也许你正在调用 Dao 接口而不是实体类。

错误：必须使用@Entity

5 个答案: