房間數據庫android中的多個過濾器

Question

我想使用房間數據庫查詢多個過濾器。 例如

 @Query("SELECT SUM(total_amount) as total FROM settlement_table where date_and_time>=:fromDate and date_and_time<=:toDate and orderType=:orderType and user_id=:user_id")
    fun getSettlementDataTotalAmountOrderTypeUserId(fromDate: Long, toDate: Long,orderType:Int?,user_id: String?): ModelSum

我遇到了user_id和orderType為空的情況。 有時任何一個都是空的。 但是當我傳遞空值時，它不返回任何數據如何使用單個查詢實現過濾器？

Answer 1

如果您需要有效的 null，那么您需要進行一些修改。

@Entity(tableName = "settlement_table")
data class Settlement(
    @PrimaryKey(autoGenerate = true) @ColumnInfo(name = "id") val id: Long = 0,
    @ColumnInfo(name = "user_id") val user_id: String? = "-1",
    @ColumnInfo(name = "orderType") val longitude: Int? = -1,
    @ColumnInfo(name = "total_amount") val total_amount: Int,
    @ColumnInfo(name = "date_and_time") val date_and_time: Long
)

將值插入為 null 時已在其中設置默認值的表。 所以，現在你的查詢將是

  @Query("SELECT SUM(total_amount) as total FROM settlement_table where date_and_time>=:fromDate and date_and_time<=:toDate and orderType=:orderType and user_id=:user_id")
    fun getSettlementDataTotalAmountOrderTypeUserId(
        fromDate: Long,
        toDate: Long,
        orderType: Int? = -1,
        user_id: String? = "-1"
    ): ModelSum

在這里你可以看到我們在插入時設置了默認值 -1 並且在執行查詢時我們也使用相同的值，如果orderType和user_id發現為空

編輯

然后你需要做一件簡單的事情，你需要創建三個同名不同參數的方法，比如方法重載。 方法 1：兩者都不為空

@Query("SELECT SUM(total_amount) as total FROM settlement_table where date_and_time>=:fromDate and date_and_time<=:toDate and orderType=:orderType and user_id=:user_id")
        fun getSettlementDataTotalAmountOrderTypeUserId(
            fromDate: Long,
            toDate: Long,
            orderType: Int,
            user_id: String
        ): ModelSum

方法 2： orderType 為 null

@Query("SELECT SUM(total_amount) as total FROM settlement_table where date_and_time>=:fromDate and date_and_time<=:toDate and user_id=:user_id")
        fun getSettlementDataTotalAmountOrderTypeUserId(
            fromDate: Long,
            toDate: Long,         
            user_id: String
        ): ModelSum

方法二：user_id為空

@Query("SELECT SUM(total_amount) as total FROM settlement_table where date_and_time>=:fromDate and date_and_time<=:toDate and orderType=:orderType")
        fun getSettlementDataTotalAmountOrderTypeUserId(
            fromDate: Long,
            toDate: Long,         
            orderType: Int
        ): ModelSum

所以在調用這個方法時你需要make條件

if(orderType!=null && user_id!=null)    {
// Call method 1
}else if(user_id!=null)    {
// Call method 2
}else if(orderType!=null)    {
// Call method 3
}

希望它可以幫助您解決您的問題