Question

你如何以不那么冗长的方式使用Slick？我的做法真的很糟糕吗？我喜欢使用我正在处理的数据库行的对象表示。

这只是彼此相关的2个实体，它花了：

import java.sql._

import scala.slick.driver.H2Driver.simple._
import scala.slick.lifted.ForeignKeyQuery

object Schema {
  val models = TableQuery[Models]
  val users = TableQuery[Users]
  val db = Database.forURL("jdbc:h2:mem:hello", driver = "org.h2.Driver")
}

object CaseClassMapping
  extends App {

  Schema.db.withSession { implicit session =>

    Schema.models.ddl.create
    Schema.users.ddl.create

    var m1 = Model(new Timestamp(new java.util.Date().getTime))
    val id = Schema.models.returning(Schema.models.map(_.id)).insert(m1)
    m1 = m1.copy(id = Some(id))
    Schema.users += User("John Doe", m1.id.get)

    val q = for {
      u <- Schema.users if u.id === 1
      m <- u.model
    } yield m

    println(Schema.users.list)
    println(q.list)
  }

}

trait _Model {
  def modelID: Int
  def model: Model
  def created = model.created
}

case class Model(created: Timestamp, id: Option[Int] = None)
class Models(tag: Tag) extends Table[Model](tag, "MODELS") {
  def id = column[Int]("ID", O.PrimaryKey, O.AutoInc)
  def created = column[Timestamp]("NAME", O.NotNull)
  def * = (created, id.?) <> (Model.tupled, Model.unapply)
}

case class User(var name: String, modelID: Int, id: Option[Int] = None)
  extends _Model {
  lazy val model = Schema.db.withSession { implicit session =>
    (for {
      u <- Schema.users if u.id === id
      m <- u.model
    } yield m).first
  }
}
class Users(tag: Tag) extends Table[User](tag, "USERS") {
  def id = column[Int]("ID", O.PrimaryKey, O.AutoInc)
  def modelID: Column[Int] = column[Int]("MODEL_ID", O.NotNull)
  def name = column[String]("NAME", O.NotNull)
  def * = (name, modelID, id.?) <> (User.tupled, User.unapply)
  def model: ForeignKeyQuery[Models, Model] =
    foreignKey("MODEL_FK", modelID, TableQuery[Models])(_.id)
}

Answer 1

您可以从架构自动生成模型。看一下这个： http://slick.typesafe.com/doc/3.0.0-RC1/code-generation.html

如何使Slick更简洁？

1 个答案: