Convert existing SBT Scala application to Play

Question

I've been working on building an application with Akka actors, and now that I've completed the actor-based business logic I'd like to give it a RESTful + websocket front-end. I'm trying to find instructions for how to setup Play within the context of an existing application. The only instructions I could find are how to create new Play applications. Is there any documentation on how to do this?

UPDATE: This question has more to do with the SBT setup than connecting the controllers to my actor based business logic. I tried to modify build.sbt and plugins.sbt to include the things that activator built when I did activator new but IDEA is complaining about Cannot resolve symbol PlayScala. Also I am wondering about moving my actors from the SBT-standard src/main/scala to app/ -- should it be in app/actors (as I saw in one of the templates) or in app/models ?

Here's my build.sbt:

name := "test"

version := "1.0-SNAPSHOT"

lazy val root = (project in file(".")).enablePlugins(play.PlayScala)

scalaVersion := "2.11.6"

libraryDependencies ++= Seq(
  jdbc,
  cache,
  ws,
  specs2 % Test
)

resolvers += "scalaz-bintray" at "http://dl.bintray.com/scalaz/releases"

scalaVersion := "2.11.6"
resolvers += "repo.novus rels" at "http://repo.novus.com/releases/"
resolvers += "repo.novus snaps" at "http://repo.novus.com/snapshots/"
libraryDependencies += "org.scalatest" % "scalatest_2.11" % "2.2.1" % "test"
libraryDependencies += "com.github.nscala-time" %% "nscala-time" % "1.8.0"
libraryDependencies += "org.slf4j" % "slf4j-simple" % "1.6.4"
libraryDependencies += "org.reactivemongo" %% "reactivemongo" % "0.10.5.0.akka23"

routesGenerator := InjectedRoutesGenerator

and here is my plugins.sbt:

logLevel := Level.Warn

// The Play plugin
addSbtPlugin("com.typesafe.play" % "sbt-plugin" % "2.4.0")

// web plugins

addSbtPlugin("com.typesafe.sbt" % "sbt-coffeescript" % "1.0.0")

addSbtPlugin("com.typesafe.sbt" % "sbt-less" % "1.0.6")

addSbtPlugin("com.typesafe.sbt" % "sbt-jshint" % "1.0.3")

addSbtPlugin("com.typesafe.sbt" % "sbt-rjs" % "1.0.7")

addSbtPlugin("com.typesafe.sbt" % "sbt-digest" % "1.1.0")

addSbtPlugin("com.typesafe.sbt" % "sbt-mocha" % "1.1.0")

Answer 1

The below changes to the project helped me to adopt PlayFramework (version:2.8.1) into the existing project:

1. In plugins.sbt add addSbtPlugin("com.typesafe.play" % "sbt-plugin" % "2.8.1")

2. In build.sbt add the below to libraryDependencies: "com.typesafe.play" %% "play" % playVersion

   2.1: Add guice support in the libraryDependencies ++= Seq(guice)

   2.2: Add the below to include /src to classpath: unmanagedSourceDirectories in Compile += baseDirectory.value / "src"

3. Add the /src directory to add it to classpath and verify:

[info] Loading global plugins from /home/training/.sbt/1.0/plugins
[info] Loading settings for project coursera-build from plugins.sbt ...
[info] Loading project definition from /home/training/IdeaProjects/coursera/project
[info] Loading settings for project root from build.sbt ...
[info] Set current project to coursera (in build file:/home/training/IdeaProjects/coursera/)
[info] * /home/training/IdeaProjects/coursera/app-2.12
[info] * /home/training/IdeaProjects/coursera/app
[info] * /home/training/IdeaProjects/coursera/app
[info] * /home/training/IdeaProjects/coursera/src

PlayFramework expects the following:

1. controllers in app/controllers - Add your controller.scala here

2. application.conf in conf

3. routes in conf - Add a route that refers to controller on step-1

Execute: sbt run

Reference: The official repo

Answer 2

UPDATE Answer:

Start in your Project File the activator Then start the web App with run and open the browser with http://localhost:9000 This loads all the dependencies and compiles the Scala Play Application.

This should correct your IDEA Ide Problems about missing Dependencies.

In Scala Play 2.4 you can choose between to Project Layouts.

• the Project layout app/
• the Project layout src/main/scala used by SBT and Maven Project is new and experimental and may have issues.

Before (Play 2.3 and smaller) there where only the Project layout app/

The three Packages

app/controllers -> Application controllers
app/models -> Application business layer
app/views -> Templates

are predefined.

You can of course add your own packages, for example an app/actors package.

Answer 3

One Part is to connect your Businesslayer (actor-based business logic - a ActorSystem) with the Controller (play.api.mvc.Controller) in the Play MVC.
The following Sample show how to do that:

import play.api.mvc._
import akka.actor._
import javax.inject._

import actors.HelloActor

@Singleton
class Application @Inject() (system: ActorSystem) extends Controller {

  val helloActor = system.actorOf(HelloActor.props, "hello-actor")

  //...
}

then you need to know some about the Play Framework:

• The Router translates each incoming HTTP request to an action call (a public method in a controller class).
• The Controller contains some Actions.
• A Action do some work in your Businesslayer (Your Actor System) and Return a Result

Now define some Route Request Paths:

- GET   /clients/all          controllers. ... .list()
- GET   /clients/:id          controllers. ... .show(id: Long)

And implement the Action in your Controller:

import play.api.libs.concurrent.Execution.Implicits.defaultContext
import scala.concurrent.duration._
import akka.pattern.ask
implicit val timeout = 5.seconds

def show(id: Long) = Action.async {
  // This ist a ask pattern returns a Future
  // Here ist the Connection between the Action from Play to your
  // Actor System - your Business Layer
  // map it to your own result type
  (helloActor ? SayHello(id)).mapTo[String].map { message =>
    Ok(message)
  }
}