Play Framework/Scala example source code file (Writeable.scala)

This example Play Framework source code file (Writeable.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Play Framework (and Scala) source code examples by using tags.

All credit for the original source code belongs to Play Framework; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Play Framework tags/keywords

a, api, array, codec, concurrent, contenttypeof, defaultwriteables, enumeratee, http, lib, library, lowprioritywriteables, play, play framework, seq, writeable

The Writeable.scala Play Framework example source code

/*
 * Copyright (C) 2009-2013 Typesafe Inc. <http://www.typesafe.com>
 */
package play.api.http

import play.api.mvc._
import play.api.libs.json._

import scala.annotation._
import play.api.libs.iteratee.Enumeratee
import play.api.libs.concurrent.Execution

import play.api.libs.concurrent.Execution.Implicits.defaultContext

/**
 * Transform a value of type A to a Byte Array.
 *
 * @tparam A the content type
 */
@implicitNotFound(
  "Cannot write an instance of ${A} to HTTP response. Try to define a Writeable[${A}]"
)
case class Writeable[-A](transform: (A => Array[Byte]), contentType: Option[String]) {
  def map[B](f: B => A): Writeable[B] = Writeable(b => transform(f(b)), contentType)
  def toEnumeratee[E <: A]: Enumeratee[E, Array[Byte]] = Enumeratee.map[E](transform)
}

/**
 * Helper utilities for `Writeable`.
 */
object Writeable extends DefaultWriteables {

  /**
   * Creates a `Writeable[A]` using a content type for `A` available in the implicit scope
   * @param transform Serializing function
   */
  def apply[A](transform: A => Array[Byte])(implicit ct: ContentTypeOf[A]): Writeable[A] = Writeable(transform, ct.mimeType)

}

/**
 * Default Writeable with lowwe priority.
 */
trait LowPriorityWriteables {

  /**
   * `Writeable` for `play.twirl.api.Content` values.
   */
  implicit def writeableOf_Content[C <: play.twirl.api.Content](implicit codec: Codec, ct: ContentTypeOf[C]): Writeable[C] = {
    Writeable(content => codec.encode(content.body))
  }

}

/**
 * Default Writeable.
 */
trait DefaultWriteables extends LowPriorityWriteables {

  /**
   * `Writeable` for `play.twirl.api.Xml` values. Trims surrounding whitespace.
   */
  implicit def writeableOf_XmlContent(implicit codec: Codec, ct: ContentTypeOf[play.twirl.api.Xml]): Writeable[play.twirl.api.Xml] = {
    Writeable(xml => codec.encode(xml.body.trim))
  }

  /**
   * `Writeable` for `NodeSeq` values - literal Scala XML.
   */
  implicit def writeableOf_NodeSeq[C <: scala.xml.NodeSeq](implicit codec: Codec): Writeable[C] = {
    Writeable(xml => codec.encode(xml.toString))
  }

  /**
   * `Writeable` for `NodeBuffer` values - literal Scala XML.
   */
  implicit def writeableOf_NodeBuffer(implicit codec: Codec): Writeable[scala.xml.NodeBuffer] = {
    Writeable(xml => codec.encode(xml.toString))
  }

  /**
   * `Writeable` for `urlEncodedForm` values
   */
  implicit def writeableOf_urlEncodedForm(implicit codec: Codec): Writeable[Map[String, Seq[String]]] = {
    import java.net.URLEncoder
    Writeable(formData =>
      codec.encode(formData.map(item => item._2.map(c => item._1 + "=" + URLEncoder.encode(c, "UTF-8"))).flatten.mkString("&"))
    )
  }

  /**
   * `Writeable` for `JsValue` values - Json
   */
  implicit def writeableOf_JsValue(implicit codec: Codec): Writeable[JsValue] = {
    Writeable(jsval => codec.encode(jsval.toString))
  }

  /**
   * `Writeable` for empty responses.
   */
  implicit val writeableOf_EmptyContent: Writeable[Results.EmptyContent] = Writeable(_ => Array.empty)

  /**
   * Straightforward `Writeable` for String values.
   */
  implicit def wString(implicit codec: Codec): Writeable[String] = Writeable[String](str => codec.encode(str))

  /**
   * Straightforward `Writeable` for Array[Byte] values.
   */
  implicit val wBytes: Writeable[Array[Byte]] = Writeable(identity)

}