Documentation

You are viewing the documentation for the 2.8.0-M4 development release. The latest stable release series is 2.7.x.

§Play 2.8 Migration Guide

This guide is for migrating from Play 2.7 to Play 2.8. See the Play 2.7 Migration Guide to upgrade from Play 2.6. It is also recommended to read Akka 2.5 to 2.6 migration guide since multiple changes there have an impact on Play 2.8.

§How to migrate

Before starting sbt, make sure to make the following upgrades.

§Play update

Update the Play version number in project/plugins.sbt:

addSbtPlugin("com.typesafe.play" % "sbt-plugin" % "2.8.x")

Where the “x” in 2.8.x is the minor version of Play you want to use, for instance 2.8.0.

§sbt upgrade

Although Play 2.8 still supports sbt 0.13, we recommend that you use sbt 1. This new version is supported and actively maintained. To update, change your project/build.properties so that it reads:

sbt.version=1.2.8

At the time of this writing 1.2.8 is the latest version in the sbt 1.x family, you may be able to use newer versions too. Check the release notes for both Play’s minor version releases and sbt’s releases for details.

§API Changes

Multiple API changes were made following our policy of deprecating the existing APIs before removing them. This section details these changes.

§Scala 2.11 support discontinued

Play 2.8 support Scala 2.12 and 2.13, dropping support for 2.11, which has reached its end of life.

§Setting scalaVersion in your project

Both Scala and Java users must configure sbt to use Scala 2.12 or 2.13. Even if you have no Scala code in your project, Play itself uses Scala and must be configured to use the right Scala libraries.

To set the Scala version in sbt, simply set the scalaVersion key, for example:

scalaVersion := "2.13.0"

If you have a single project build, then this setting can just be placed on its own line in build.sbt. However, if you have a multi-project build, then the scala version setting must be set on each project. Typically, in a multi-project build, you will have some common settings shared by every project, this is the best place to put the setting, for example:

def commonSettings = Seq(
  scalaVersion := "2.13.0"
)

val projectA = (project in file("projectA"))
  .enablePlugins(PlayJava)
  .settings(commonSettings)

val projectB = (project in file("projectB"))
  .enablePlugins(PlayJava)
  .settings(commonSettings)

§Deprecated APIs were removed

Many APIs that were deprecated in earlier versions were removed in Play 2.8. If you are still using them we recommend migrating to the new APIs before upgrading to Play 2.8. Check the Javadocs and Scaladocs for migration notes. See also the migration guide for Play 2.7 for more information.

§Scala API

  1. xxx
  2. xxx

Some new methods were added to improve the Scala API too:

xxx

§Java API

  1. In Play 2.7 we deprecate play.mvc.Http.Context in favor of directly using play.mvc.Http.RequestHeader or play.mvc.Http.Request. We have now removed Http.Context and if your application was still depending on it, you should read Play 2.7 migration guide instructions.
  2. xxx

Some new methods were added to improve the Java API too:

xxx

§Internal changes

Many changes have been made to Play’s internal APIs. These APIs are used internally and don’t follow a normal deprecation process. Changes may be mentioned below to help those who integrate directly with Play internal APIs.

§Configuration changes

This section lists changes and deprecations in configurations.

§ObjectMapper serialization change

Play 2.8 adopts Akka Jackson Serialization support and then uses the defaults provided by Akka. One of the changes is how Java Time types are rendered. Until Play 2.7 they were rendered as timestamps, which has better performance, but now they are rendered using ISO-8601 (rfc3339) format (yyyy-MM-dd'T'HH:mm:ss.SSSZ).

If you need to use the old timestamps default format, then add the following configuration in your application.conf:

akka.serialization.jackson.play.serialization-features.WRITE_DATES_AS_TIMESTAMPS = on

§Dropped the overrides for akka.actor.default-dispatcher.fork-join-executor

The overrides that Play had under akka.actor.default-dispatcher.fork-join-executor have been dropped in favour of using Akka’s new-and-improved defaults.

See the section related to changes in the default dispatch in Akka’s migration guide for more details.

§IOSource and FileIO changes in Akka Streams

There are changes related to how Akka Streams handle errors for FileIO.toPath, StreamConverters.fromInputStream, and StreamConverters.fromOutputStream. See the section related to these changes in Akka’s migration guide for more details.

§Configuration loading changes

Until Play 2.7, when loading configuration, Play was not considering the default Java System Properties if the user provides some properties. Now, System Properties are always considered, meaning that you can reference them in your application.conf file even if you are also defining custom properties. For example, when embedding Play like the code below, both userProperties and System Properties are used:

import java.util.Properties

import play.api.mvc.Results
import play.core.server.AkkaHttpServer
import play.core.server.ServerConfig
import play.api.routing.sird._

class MyApp {
  def main(args: Array[String]): Unit = {
    // Define some user properties here
    val userProperties = new Properties()
    userProperties.setProperty("my.property", "some value")

    val serverConfig = ServerConfig(properties = userProperties)

    val server = AkkaHttpServer.fromRouterWithComponents(serverConfig) { components => {
      case GET(p"/hello") => components.defaultActionBuilder {
        Results.Ok
      }
    }}
  }
}

Keep in mind that user-defined properties have precedence over default System Properties.

§Debugging SSL Connections

Until Play 2.7, both Play and Play-WS were using a version of ssl-config which had a debug system that relied on undocumented modification of internal JSSE debug settings. These are usually set using javax.net.debug and java.security.debug system properties on startup.

This debug system has been removed, the debug flags that do not have a direct correlation in the new system are deprecated, and the new configuration is documented in ssl-config docs.

§Defaults changes

Some of the default values used by Play had changed and that can have an impact on your application. This section details the default changes.

§Content-Disposition: inline header not send anymore when serving files

When serving files via the Scala API or the Java API Play by default generates the Content-Disposition header automatically and sends it to the client.

Starting with Play 2.8 however, when the computed header ends up being exactly Content-Disposition: inline (when passing inline = true, which is the default, and null as file name), it wont be send by Play automatically anymore. Because, according to RFC 6266 Section 4.2, rendering content inline is the default anyway.
Therefore this change should not effect you at all, since all browsers adhere to the specs and do not treat this header in any special way but to render content inline, like no header was send.

If you still want to send this exact header however, you can still do that by using the withHeader(s) methods from Scala's or Java's Result class.

§Updated libraries

This section lists significant updates made to our dependencies.

§Removed libraries

To make the default play distribution a bit smaller we removed some libraries. The following libraries are no longer dependencies in Play 2.8, so you will need to add them manually to your build if you use them.

§Other important changes

Next: Play 2.7