带有分组查询的 Scala 光滑连接表

如何解决带有分组查询的 Scala 光滑连接表

我有两张桌子：

购物

class ShopTable(tag: Tag) 扩展 GenericTableShop,UUID {

 def * = (id.?,name,address) <> (Shop.tupled,Shop.unapply _)

 def name = column[String]("name")

 def address = column[String]("address")

}

val shopTable = TableQuery[ShopDAO.ShopTable]

订购

class OrderTable(tag: Tag) extends GenericTableOrder,shopId,amount) <> (Order.tupled,Order.unapply _) def shopId = column[UUID]("shop_id") def amount = column[Double]("amount")
}

val orderTable = TableQuery[OrderDAO.OrderTable]

我可以获得商店的静态（订单数、订单金额总和）：

def getStatisticForShops(shopIds: List[UUID]): Future[Seq(UUID,Int,Double)] = {
  searchStatisticsByShopIds(shopIds).map(orderStatistics => 
    shopIds.map(shopId => {
      val o = orderStatistics.find(_._1 == shopId)
      (
        shopId,o.map(_._2).getorElse(0),o.map(_._3).getorElse(0.0)
      )
    })
  )
}

 def searchStatisticsByShopIds(shopIds: List[UUID]): Future[Seq(UUID,Double)] = 
  db.run(searchStatisticsByShopIdsCompiled(shopIds).result)

 private val searchStatisticsByShopIdsCompiled = Compiled((shopIds: Rep[List[(UUID)]]) =>
  orderTable.filter(_.shopId === shopIds.any)
    .groupBy(_.shopId)
    .map { case (shopId,row) =>
      (shopId,row.length,row.map(_.amount).sum.get)
    }
 )

我需要按订单数对 shopTable 进行排序和过滤。

如何将分组的 orderTable 加入到 shopTable 中，缺失商店的值为零？

我想要一个这样的请求：

| id(shopId) | name | address | ordersCount | ordersAmount |
|     id1    | name | address |       4     |    200.0     |
|     id2    | name | address |       0     |     0.0      |
|     id3    | name | address |       2     |    300.0     |

我使用 scala 2.12.6、slick 2.12:3.0.1、play-slick 3.0.1、slick-pg 0.16.3

P.S.我可能找到了解决方案

val shopsOrdersQuery: Query[(Rep[UUID],Rep[Int],Rep[Double]),(UUID,Double),Seq] = searchShopsOrdersCompiled.extract

// Query shops with orders for sorting and filtering
val allShopsOrdersQueryQuery = shopTable.joinLeft(shopsOrdersQuery).on(_.id === _._1)
  .map(s => (s._1,s._2.map(_._2).getorElse(0),s._2.map(_._3).getorElse(0.0)))

private val searchShopsOrdersCompiled = Compiled(
  orderTable.groupBy(_.shopId)
    .map { case (shopId,row.map(_.amount).sum.get)
    }
)

解决方法

是的，这个解决方案工作正常

val shopsOrdersQuery: Query[(Rep[UUID],Rep[Int],Rep[Double]),(UUID,Int,Double),Seq] = searchShopsOrdersCompiled.extract

// Query shops with orders for sorting and filtering
val allShopsOrdersQueryQuery = shopTable.joinLeft(shopsOrdersQuery).on(_.id === _._1)
  .map(s => (s._1,s._2.map(_._2).getOrElse(0),s._2.map(_._3).getOrElse(0.0)))

private val searchShopsOrdersCompiled = Compiled(
  orderTable.groupBy(_.shopId)
    .map { case (shopId,row) =>
      (shopId,row.length,row.map(_.amount).sum.get)
    }
)