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§Using Play Slick

The Play Slick module makes Slick a first-class citizen of Play.

The Play Slick module consists of 3 features:

A wrapper DB object that uses the datasources defined in the Play config files, and pulls them from a connection pool. It is there so it is possible to use Slick sessions in the same fashion as you would Anorm JDBC connections. There are some smart caching and load balancing that makes your connections to your DB more performant.
A DDL plugin, that reads Slick tables and automatically creates schema updates on reload. This is useful in particular for demos and to get started.
A wrapper to use play enumeratees together with Slick.

§Setup

Add a library dependency on play-slick. See the play-slick README for the latest library dependency and version information.

Configure the database in your application.conf as for other Play databases. For example:

db.default.driver=org.h2.Driver
db.default.url="jdbc:h2:mem:play"
db.default.user=sa
db.default.password=""

Using the following import:

import play.api.db.slick.Config.driver.simple._

will import the Slick driver based on the db.default.driver configuration in application.conf, or the one set by the test helpers in test mode.

If you need to use more than one database driver per mode (run or test), please read the information about using multiple drivers.

For more information about creating models see the Slick documentation.

§DBAction

Use the DBAction in lieu of Action when you need an implicit Session in your controller.

The DBAction is predicated, meaning that it returns an error if the amount of requests are higher than a threshold. This means that your users will get an error when traffic is too high, instead of taking down the whole system.

Import DBAction and useful implicits with:

import play.api.db.slick._

Example usage of DBAction:

def index(name: String) = DBAction { implicit rs =>
  val users = Users.filter(_.name === name)
  Ok(views.html.index(users.list))
}

Note: rs contains the Play request and the Slick session. You can access the Play request via rs.request and the Slick session via rs.dbSession.

If you find yourself in need of combining the DBAction, consider using the DB wrapper directly instead.

It is also possible to extend the DefaultDBAction or PredicatedDBAction to customise behaviour. The source code contains more descriptions of how to do this: https://github.com/playframework/play-slick/blob/master/code/src/main/scala/play/api/db/slick/DBAction.scala#L16

§DDL plugin

In order to enable DDL schema generation you must specify the packages or classes you want to have in the application.conf file:

slick.default="models.*"

It follows the same format as the Ebean plugin: models.* means all Tables in the models package should be run on the default database.

It is possible to specify individual objects like:

slick.default="models.Users,models.Settings"

§DB wrapper

The DB wrapper is just a thin wrapper that uses Slick’s Database classes with databases in the Play application.

You can import DB with:

import play.api.db.slick.DB

A Play Application can be passed to DB explicitly, or to use the currently running Play application implicitly use the following import:

// import implicit Application
import play.api.Play.current

Here’s an example of using the DB wrapper:

DB.withSession { implicit session =>
  Users.insert(User("fredrik", "ekholdt"))
}

For transactions use the withTransaction method:

DB.withTransaction{ implicit session =>
  Users.insert(User("fredrik", "ekholdt"))
  if (someFailure) {
    session.rollback
  }
}

Next: Play Slick resources