Question

我正在使用android jetpack进行android编程，需要检索某些列的计数，问题是我不知道如何将COUNT（column）的列映射到房间实体中，我是我收到此错误：

 Caused by: java.lang.IllegalArgumentException: column '`COUNT(Deuda.id)`' does not exist. Available columns: [COUNT(Deuda.id), COUNT(pagado)]
    at android.database.AbstractCursor.getColumnIndexOrThrow(AbstractCursor.java:340)
    at androidx.room.util.CursorUtil.getColumnIndexOrThrow(CursorUtil.java:108)
    at room.components.daos.DeudaDAO_Impl$13.call(DeudaDAO_Impl.java:568)
    at room.components.daos.DeudaDAO_Impl$13.call(DeudaDAO_Impl.java:563)
    at androidx.room.RoomTrackingLiveData$1.run(RoomTrackingLiveData.java:90)

这是我的查询：

@Query("SELECT COUNT(Deuda.id), COUNT(pagado) FROM Deuda GROUP BY tipo")
fun getCuentaTiposDeuda() : LiveData<List<CantidadTipoDeuda>>

这是我要执行查询的实体：

@Entity(foreignKeys = arrayOf(
    ForeignKey(entity = Cuenta::class,
    parentColumns = arrayOf("id"),
    childColumns = arrayOf("cuenta_id"),
    onDelete = ForeignKey.CASCADE)
))
class Deuda(@PrimaryKey(autoGenerate = true) var id: Int,
            var titulo: String? = null,
            var tipo: Int = 0,
            var monto: Float = 0f,
            var nota: String? = null,
            var fecha_adquision: String? = null,
            var pagado: Float = 0f,
            var estado: Int? = null,
            var cuenta_id: Int? = null
            )

这是我要存储结果的房间实体：

import androidx.room.ColumnInfo

data class CantidadTipoDeuda (
    @ColumnInfo(name = "COUNT(Deuda.id)") val tipoDeuda: Float?,
    @ColumnInfo(name = "COUNT(pagado)") val cantidadPorTipo: Float?
)

那么，如何使用房间处理COUNT个？

如何将COUNT（列）映射到Room实体？

0 个答案: