Getting autoincrement values with Slick library in Scala

问题

How do I get the auto-incremented values for records inserted with Slick? The following code prints 1111. I would have expected it to print 1234

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

object TestMappedTable extends App{
    case class User(id: Option[Int], first: String, last: String)

    object Users extends Table[User]("users") {
        def id = column[Int]("id", O.PrimaryKey, O.AutoInc)
        def first = column[String]("first")
        def last = column[String]("last")
        def * = id.? ~ first ~ last <> (User, User.unapply _)
    }

  implicit val session = Database.forURL("jdbc:h2:mem:test1", driver = "org.h2.Driver").createSession()
  session.withTransaction{
    Users.ddl.create

    print(Users.insert(User(None, "Jack", "Green" )))
    print(Users.insert(User(None, "Joe", "Blue" )))
    print(Users.insert(User(None, "John", "Purple" )))
    print(Users.insert(User(None, "Jim", "Yellow" )))
  }
}

I'm using Slick 0.11.2 for Scala 2.10.0-RC1

回答1:

You can retrieve the generated value like this.

Add autoInc method to Users object.

def autoInc = id.? ~ first ~ last <> (User, User.unapply _) returning id

Use Users.autoInc.insert instead.

print(Users.autoInc.insert(User(None, "Jack", "Green" )))

回答2:

The latest version of Slick (2.1.0) automatically takes care of ignoring the auto-incremented ids and the documentation demonstrates how to retrieve the id:

val userWithId =
  (users returning users.map(_.id)
         into ((user,id) => user.copy(id=Some(id)))
  ) += User(None, "Stefan", "Zeiger")

This is the full monty, where the retrieved value is then inserted back into the object you are adding to the table. If you just want to get your hands on the id itself:

val userId =
  (users returning users.map(_.id)) += User(None, "Stefan", "Zeiger")

Both code snippets were taken from the official docs. It seemed like this question needed updating for newcomers (like me) who have never used earlier versions of Slick.

回答3:

According to SLICK Inserting document, you should define a method forInsert looks like:

def forInsert = first ~ last <> (
    { t =>
        User(None, t._1, t._2)},
    { (u: User) =>
        Some((u.first, u.last))
    }) returning id

To get result:

def save(user: User): User = {
    val id = users.forInsert.insert(user)
    new User(Some(id), user.first, user.last)
}

回答4:

For me, following source worked (Slick 3.0.2)

class Track(tag: Tag)
   extends Table[(Int, String, String)](tag, "TRACK") {
   // This is the primary key column:
   def id: Rep[Int] = column[Int]("ID", O.PrimaryKey, O.AutoInc)
   def artist: Rep[String] = column[String]("ARTIST")
   def name: Rep[String] = column[String]("NAME")

   def * : ProvenShape[(Int, String, String)] =
     (id, artist, name)
}

来源：https://stackoverflow.com/questions/13114255/getting-autoincrement-values-with-slick-library-in-scala

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