Scala 玩 withSession 已弃用

Question

我正在从 slick 2.1 迁移到 3.0。如您所知，withSession 函数已被弃用。

如何更改以下代码：

def insert(vote: Vote) = DB.withSession { implicit session =>
  insertWithSession(vote)
}
def insertWithSession(vote: Vote)(implicit s: Session) = {
  Votes.insert(vote)
}

Votes.insert 出现编译错误，错误是：

could not find implicit value for parameter s: slick.driver.PostgresDriver.api.Session

最后，除了official link，还有其他文档帮助我迁移吗？我需要更多详细信息。

Answer 1

假设您使用 play-slick 来实现与 play 的巧妙集成。

您可以查看https://www.playframework.com/documentation/2.5.x/PlaySlick了解更多详情。

在 build.sbt 中添加 slick 和 jdbc 依赖项

libraryDependencies ++= Seq(
  "com.typesafe.play" %% "play-slick" % "2.0.0",
  "com.typesafe.play" %% "play-slick-evolutions" % "2.0.0"
  "org.postgresql" % "postgresql" % "9.4-1206-jdbc4"
)

在你的 application.conf 中添加 postgres 配置

slick.dbs.default.driver="slick.driver.PostgresDriver$"
slick.dbs.default.db.driver="org.postgresql.Driver"
slick.dbs.default.db.url="jdbc:postgresql://localhost/yourdb?user=postgres&password=postgres"

现在像下面这样定义你的模型，

package yourproject.models

import play.api.db.slick.DatabaseConfigProvider
import slick.driver.JdbcProfile

case class Vote(subject: String, number: Int)

class VoteTable(tag: Tag) extends Table[Vote](tag, "votes") {
  def id = column[Int]("id", O.PrimaryKey, O.AutoInc)
  def subject = column[String]("subject")
  def number = column[Int]("number")

  def * = (id.?, subject, number) <> (Vote.tupled, Vote.unapply)
}

class VoteRepo @Inject()()(protected val dbConfigProvider: DatabaseConfigProvider) {
  val dbConfig = dbConfigProvider.get[JdbcProfile]
  val db = dbConfig.db
  import dbConfig.driver.api._

  val Votes = TableQuery[VoteTable]

  def insert(vote: Vote): DBIO[Long] = {
    Votes returning Votes.map(_.id) += vote
  }

}

现在你的控制器看起来像，

import javax.inject.Inject

import yourproject.models.{VoteRepo}
import play.api.libs.concurrent.Execution.Implicits.defaultContext
import play.api.mvc.{Action, Controller}

class Application @Inject()(voteRepo: VoteRepo) extends Controller {

  def createProject(subject: String, number: Int) = Action.async {
    implicit rs => {
      voteRepo.create(Vote(subject, number))
        .map(id => Ok(s"project $id created") )
    }
  }

}