Slick 3.0.0 database agnostism

Question

I started to use Slick 3.0.0 and I like it's succinct syntax. Nevertheless, I wasn't able to find a way to use it in a database agnostic way.

In the following example provided in the documentation: http://slick.typesafe.com/doc/3.0.0/gettingstarted.html

I'd like to be able to decouple somehow this code of the database used and avoid importing database specific in my code (i.e slick.driver.H2Driver.api._).

I tried to get rid of it by providing the connection using the cake pattern, but the ".result" member isn't available then.

A workaround would be to import slick.driver.JdbcDriver.api._, but it is deprecated and thus should not be a good starting point.

Anyone found a way to use Slick 3.0.0 in a database agnostic and elegant way?

This question isn't far of "How to write database-agnostic Play application and perform first-time database initialization?", but that one focuses on Slick 3.0.0. Sadely the answers provided with that former question aren't targetting Slick 3.0.0 except one which uses deprecated code.

Answer 1

The slick driver class you're looking for is slick.driver.JdbcProfile.

There's an official example project slick-multidb which you can obtain through activator (github). Here's the relevant code:

import scala.language.higherKinds
import slick.driver.JdbcProfile

/** All database code goes into the DAO (data access object) class which
  * is parameterized by a Slick driver that implements JdbcProfile.
  */
class DAO(val driver: JdbcProfile) {
  // Import the Scala API from the driver
  import driver.api._

  class Props(tag: Tag) extends Table[(String, String)](tag, "PROPS") {
    def key = column[String]("KEY", O.PrimaryKey)
    def value = column[String]("VALUE")
    def * = (key, value)
  }
  val props = TableQuery[Props]

  /** Create the database schema */
  def create: DBIO[Unit] =
    props.ddl.create

  /** Insert a key/value pair */
  def insert(k: String, v: String): DBIO[Int] =
    props += (k, v)

  /** Get the value for the given key */
  def get(k: String): DBIO[Option[String]] =
    (for(p <- props if p.key === k) yield p.value).result.headOption

  /** Get the first element for a Query from this DAO */
  def getFirst[M, U, C[_]](q: Query[M, U, C]): DBIO[U] =
    q.result.head
}

Client code:

val dao = new DAO(H2Driver)
import dao.driver.api._
db.run(dao.insert("foo", "bar"))