如何使用 Android Studio 中的 Room 和 Kotlin 查詢零件字段的記錄？

Question

在帶有 Kotlin 的 Android Studio 中使用帶有 Room 框架的fun listVoice():LiveData<List<MVoice>>來查詢記錄 MVoice 效果很好。

現在我希望查詢MVoice的部分字段（如ID和name ）的記錄，我該怎么辦？

interface DBVoiceDao{
   @Query("SELECT * FROM voice_table ORDER BY createdDate desc")
   fun listVoice():LiveData<List<MVoice>>

   /*  How can I do this?
   @Query("SELECT id, name FROM voice_table ORDER BY createdDate desc")
   fun listVoiceOfPartField():LiveData< ??? >
   */
}



@Entity(tableName = "voice_table", indices = [Index("createdDate")])
data class MVoice(
    @PrimaryKey (autoGenerate = true) @ColumnInfo(name = "id") var id: Int = 0,
    var name:          String = "Untitled",
    var path:          String = "My path",
    var createdDate:   Calendar = Calendar.getInstance(),
    var isStar:        Boolean = false,
    var description:   String="My description"
)

Answer 1

正如“ Florina Muntenescu ”所建議的那樣，在本文中閱讀您需要的內容7 房間專業提示

您可以通過制作新的 Model Class 來實現它：

data class VoiceMinimal(@ColumnInfo(name = "id") val id: Int,
                        @ColumnInfo(name = "name") val name: String)

在 DAO class 中，我們定義了查詢和 select 來自語音表的右列。

@Dao
interface DBVoiceDao {
    @Query(“SELECT id, name FROM voice_table ORDER BY createdDate dESC)
    fun getVoiceMinimal(): List<VoiceMinimal>
}