如何连接两个表并将结果映射到光滑的案例类

Question

我正在一个使用 scala play 2 框架的项目中工作，我使用 slick 作为 FRM 和 postgres 数据库。

在我的项目中，客户是一个实体。所以我也创建了一个客户表和客户案例类和对象。另一个实体是帐户。所以我也创建了一个帐户表和帐户案例类和对象。代码如下

case class Customer(id: Option[Int],
            status: String,
            balance: Double,
            payable: Double,
            created: Option[Instant],
            updated: Option[Instant]) extends GenericEntity {
def this(status: String,
   balance: Double,
   payable: Double) = this(None, status, balance, payable, None, None)
}
class CustomerTable(tag: Tag) extends GenericTable[Customer](tag, "customer"){
   override def id = column[Option[Int]]("id")
   def status = column[String]("status")
   def balance = column[Double]("balance")
   def payable = column[Double]("payable")
   def account = foreignKey("fk_customer_account", id, Accounts.table)(_.id,    onUpdate = ForeignKeyAction.Restrict, onDelete = ForeignKeyAction.Cascade)

def * = (id, status, balance, payable, created, updated) <> ((Customer.apply _).tupled, Customer.unapply)
}
object Customers extends GenericService[Customer, CustomerTable] {
   override val table = TableQuery[CustomerTable]
   val accountTable = TableQuery[AccountTable]
   override def copyEntityFields(entity: Customer, id: Option[Int],
   created: Option[Instant], updated: Option[Instant]): Customer = {
      entity.copy(id = id, created = created, updated = updated)
   }
}

现在我想加入客户表和帐户表并将结果映射到名为 CustomerWithAccount 的案例类 我试过下面的代码

case class CustomerDetail(id: Option[Int],
                      status: String,
                      name: String)
object Customers extends GenericService[Customer, CustomerTable] {
   override val table = TableQuery[CustomerTable]
   val accountTable = TableQuery[AccountTable]
   def getAllCustomersWithAccount = db.run(table.join(accountTable).on(_.id === _.id).map { row =>
   //for (row1 <- row) {
     for {
       id <- row._1.id
       status <- row._1.status.toString()
       name <- row._2.name.toString()
     } yield CustomerDetail(id = id, status = status, name = name)
   //}
   }.result)
   override def copyEntityFields(entity: Customer, id: Option[Int], created:Option[Instant], updated: Option[Instant]): Customer = {
    entity.copy(id = id, created = created, updated = updated)
  }
}

但这不起作用。 请帮帮我。

Answer 1

你可以试试这个查询

db.run((table.join(accountTable).on(_.id === _.id)
  .map{
    case (t,a) => ((t.id, t.status, a.name) <> (CustomerDetail.tupled, CustomerDetail.unapply _))
  }).result)

Answer 2

您可以使用 3 个案例类来执行此操作，每个表 1 个，然后 1 个用于连接结果。

db.run((customerTable.join(accountTable).on(_.id === _.id)
  .map{
     case (c,a) => CustomerWithAccount(status = c.status, created = 
                    c.created, account=a, ...)
   }