如何连接两个表并将结果映射到Slick中的case类 [英] How to join two tables and map the result to a case class in slick

问题描述

我正在使用scala play 2框架在一个项目中工作，在该框架中，我使用slick作为FRM和postgres数据库.

I am working in a project with scala play 2 framework where i am using slick as FRM and postgres database.

在我的项目中，客户是一个实体.因此，我还创建了一个客户表以及客户案例类和对象.另一个实体是帐户.因此，我还创建了一个帐户表以及帐户案例类和对象.代码如下所示

In my project customer is an entity. So i create a customer table and customer case class and object also. Another entity is account. So i create a account table and account case class and object also. The code is given bellow

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，我要加入客户表"和客户表"，并将结果映射到名为CustomerWithAccount的案例类中. 我尝试了以下代码

Now I Want to join Customer Table and Account Table and map the result to a case class named CustomerWithAccount I have tried the following code

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)
  }
}

但是这没有用. 请帮助我.

But this did not work. Please help me.

推荐答案

您可以尝试此查询

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

这篇关于如何连接两个表并将结果映射到Slick中的case类的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！