Shapeless HList support for Slick.

by Richard Dallaway, Miles Sabin, and Dave Gurnell.

Copyright 2015-2019 Underscore Consulting LLP. Licensed Apache 2.

Scala	Slick	Slickless
2.13	3.3
2.12	3.3
2.12	3.2	0.3.3
2.11	3.1	0.3.0

Grab the code by adding the following to your build.sbt:

libraryDependencies ++= Seq(
  "com.typesafe.slick" %% "slick"     % "3.3.2",
  "com.chuusai"        %% "shapeless" % "2.3.3",
  "io.underscore"      %% "slickless" % "<<VERSION>>"
)

Import Slick, shapeless, and slickless, and you should be able to define Tables on any shapeless HList type:

import slick.jdbc.H2Profile.api._
import shapeless.{ HList, ::, HNil }
import slickless._

class Users(tag: Tag) extends Table[Long :: String :: HNil](tag, "users") {
  def id    = column[Long]( "id", O.PrimaryKey, O.AutoInc )
  def email = column[String]("email")

  def * = id :: email :: HNil
}

lazy val users = TableQuery[Users]

If you want to map your HList to a case class (i.e. you have a case class that has more than 22 fields and you are using slickless to bypass this limit), you can do the following

import slick.jdbc.H2Profile.api._
import shapeless.{ HList, ::, HNil, Generic }
import slickless._

case class User(id: Long, email: String)

class Users(tag: Tag) extends Table[User](tag, "users") {
  def id    = column[Long]( "id", O.PrimaryKey, O.AutoInc )
  def email = column[String]("email")

  def * = (id :: email :: HNil).mappedWith(Generic[User])
}

lazy val users = TableQuery[Users]

Due to this issue, if you accidentally make a mapping which is incorrect, the Scala compiler can take a huge amount of time to report an error. If your slickless project is taking an insanely long amount of time to compile (more than a couple of minutes), try to make sure you have the mapping correct before using <>.

If you need to add resolvers into your build, here's an example:

resolvers += "Maven Central" at "https://repo1.maven.org/maven2/"

resolvers += Resolver.sonatypeRepo("releases")

resolvers += Resolver.sonatypeRepo("snapshots")

libraryDependencies ++= Seq(
  "com.typesafe.slick" %% "slick"     % "3.2.1",
  "com.chuusai"        %% "shapeless" % "2.3.3",
  "io.underscore"      %% "slickless" % "0.3.3"
)

We use the sbt-pgp plugin and the sbt-sonatype plugin to publish to Maven Central.

Publish sequence could be:

sbt> set pgpPassphrase := Some(Array('s','e','c','r','3','t'))
sbt> set publishTo := sonatypePublishTo.value
sbt> +publishSigned
sbt> sonatypeRelease