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

This example Play Framework source code file (Writes.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, b, collection, jsnumber, jsobject, json, jsvalue, library, owrites, pathwrites, play framework, reflection, string, value, writes

The Writes.scala Play Framework example source code

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

import scala.annotation.implicitNotFound
import scala.collection._
import scala.reflect.ClassTag

import com.fasterxml.jackson.databind.JsonNode
import com.fasterxml.jackson.databind.node.{ ArrayNode, ObjectNode }

import Json._

/**
 * Json serializer: write an implicit to define a serializer for any type
 */
@implicitNotFound(
  "No Json serializer found for type ${A}. Try to implement an implicit Writes or Format for this type."
)
trait Writes[-A] {

  /**
   * Convert the object into a JsValue
   */
  def writes(o: A): JsValue

  /**
   * transforms the resulting JsValue using transformer function
   */
  def transform(transformer: JsValue => JsValue): Writes[A] = Writes[A] { a => transformer(this.writes(a)) }

  /**
   * transforms resulting JsValue using Writes[JsValue]
   */
  def transform(transformer: Writes[JsValue]): Writes[A] = Writes[A] { a => transformer.writes(this.writes(a)) }

}

@implicitNotFound(
  "No Json serializer as JsObject found for type ${A}. Try to implement an implicit OWrites or OFormat for this type."
)
trait OWrites[-A] extends Writes[A] {

  def writes(o: A): JsObject

}

object OWrites extends PathWrites with ConstraintWrites {
  import play.api.libs.functional._

  implicit val functionalCanBuildOWrites: FunctionalCanBuild[OWrites] = new FunctionalCanBuild[OWrites] {

    def apply[A, B](wa: OWrites[A], wb: OWrites[B]): OWrites[A ~ B] = OWrites[A ~ B] { case a ~ b => wa.writes(a).deepMerge(wb.writes(b)) }

  }

  implicit val contravariantfunctorOWrites: ContravariantFunctor[OWrites] = new ContravariantFunctor[OWrites] {

    def contramap[A, B](wa: OWrites[A], f: B => A): OWrites[B] = OWrites[B](b => wa.writes(f(b)))

  }

  def apply[A](f: A => JsObject): OWrites[A] = new OWrites[A] {
    def writes(a: A): JsObject = f(a)
  }

}

/**
 * Default Serializers.
 */
object Writes extends PathWrites with ConstraintWrites with DefaultWrites {

  val constraints: ConstraintWrites = this
  val path: PathWrites = this

  /*implicit val contravariantfunctorWrites:ContravariantFunctor[Writes] = new ContravariantFunctor[Writes] {

    def contramap[A,B](wa:Writes[A], f: B => A):Writes[B] = Writes[B]( b => wa.writes(f(b)) )

  }*/

  def apply[A](f: A => JsValue): Writes[A] = new Writes[A] {

    def writes(a: A): JsValue = f(a)

  }

}

/**
 * Default Serializers.
 */
trait DefaultWrites {

  /**
   * Serializer for Int types.
   */
  implicit object IntWrites extends Writes[Int] {
    def writes(o: Int) = JsNumber(o)
  }

  /**
   * Serializer for Short types.
   */
  implicit object ShortWrites extends Writes[Short] {
    def writes(o: Short) = JsNumber(o)
  }

  /**
   * Serializer for Long types.
   */
  implicit object LongWrites extends Writes[Long] {
    def writes(o: Long) = JsNumber(o)
  }

  /**
   * Serializer for Float types.
   */
  implicit object FloatWrites extends Writes[Float] {
    def writes(o: Float) = JsNumber(o)
  }

  /**
   * Serializer for Double types.
   */
  implicit object DoubleWrites extends Writes[Double] {
    def writes(o: Double) = JsNumber(o)
  }

  /**
   * Serializer for BigDecimal types.
   */
  implicit object BigDecimalWrites extends Writes[BigDecimal] {
    def writes(o: BigDecimal) = JsNumber(o)
  }

  /**
   * Serializer for Boolean types.
   */
  implicit object BooleanWrites extends Writes[Boolean] {
    def writes(o: Boolean) = JsBoolean(o)
  }

  /**
   * Serializer for String types.
   */
  implicit object StringWrites extends Writes[String] {
    def writes(o: String) = JsString(o)
  }

  /**
   * Serializer for Jackson JsonNode
   */
  implicit object JsonNodeWrites extends Writes[JsonNode] {
    def writes(o: JsonNode): JsValue = JacksonJson.jsonNodeToJsValue(o)
  }

  /**
   * Serializer for Array[T] types.
   */
  implicit def arrayWrites[T: ClassTag](implicit fmt: Writes[T]): Writes[Array[T]] = new Writes[Array[T]] {
    def writes(ts: Array[T]) = JsArray((ts.map(t => toJson(t)(fmt))).toList)
  }

  /**
   * Serializer for Map[String,V] types.
   */
  implicit def mapWrites[V](implicit fmtv: Writes[V]): OWrites[collection.immutable.Map[String, V]] = OWrites[collection.immutable.Map[String, V]] { ts =>
    JsObject(ts.map { case (k, v) => (k, toJson(v)(fmtv)) }.toList)
  }

  /**
   * Serializer for Traversables types.
   */
  implicit def traversableWrites[A: Writes] = new Writes[Traversable[A]] {
    def writes(as: Traversable[A]) = JsArray(as.map(toJson(_)).toSeq)
  }

  /**
   * Serializer for JsValues.
   */
  implicit object JsValueWrites extends Writes[JsValue] {
    def writes(o: JsValue) = o
  }

  /**
   * Serializer for Option.
   */
  implicit def OptionWrites[T](implicit fmt: Writes[T]): Writes[Option[T]] = new Writes[Option[T]] {
    def writes(o: Option[T]) = o match {
      case Some(value) => fmt.writes(value)
      case None => JsNull
    }
  }

  /**
   * Serializer for java.util.Date
   * @param pattern the pattern used by SimpleDateFormat
   */
  def dateWrites(pattern: String): Writes[java.util.Date] = new Writes[java.util.Date] {
    def writes(d: java.util.Date): JsValue = JsString(new java.text.SimpleDateFormat(pattern).format(d))
  }

  /**
   * Default Serializer java.uti.Date -> JsNumber(d.getTime (nb of ms))
   */
  implicit object DefaultDateWrites extends Writes[java.util.Date] {
    def writes(d: java.util.Date): JsValue = JsNumber(d.getTime)
  }

  /**
   * Serializer for org.joda.time.DateTime
   * @param pattern the pattern used by SimpleDateFormat
   */
  def jodaDateWrites(pattern: String): Writes[org.joda.time.DateTime] = new Writes[org.joda.time.DateTime] {
    def writes(d: org.joda.time.DateTime): JsValue = JsString(d.toString(pattern))
  }

  /**
   * Default Serializer org.joda.time.DateTime -> JsNumber(d.getMillis (nb of ms))
   */
  implicit object DefaultJodaDateWrites extends Writes[org.joda.time.DateTime] {
    def writes(d: org.joda.time.DateTime): JsValue = JsNumber(d.getMillis)
  }

  /**
   * Serializer for org.joda.time.LocalDate
   * @param pattern the pattern used by org.joda.time.format.DateTimeFormat
   */
  def jodaLocalDateWrites(pattern: String): Writes[org.joda.time.LocalDate] = new Writes[org.joda.time.LocalDate] {
    def writes(d: org.joda.time.LocalDate): JsValue = JsString(d.toString(pattern))
  }

  /**
   * Default Serializer org.joda.time.LocalDate -> JsString(ISO8601 format (yyyy-MM-dd))
   */
  implicit object DefaultJodaLocalDateWrites extends Writes[org.joda.time.LocalDate] {
    def writes(d: org.joda.time.LocalDate): JsValue = JsString(d.toString)
  }

  /**
   * Serializer for java.sql.Date
   * @param pattern the pattern used by SimpleDateFormat
   */
  def sqlDateWrites(pattern: String): Writes[java.sql.Date] = new Writes[java.sql.Date] {
    def writes(d: java.sql.Date): JsValue = JsString(new java.text.SimpleDateFormat(pattern).format(d))
  }

  /**
   * Serializer for java.util.UUID
   */
  implicit object UuidWrites extends Writes[java.util.UUID] {
    def writes(u: java.util.UUID) = JsString(u.toString())
  }

  /**
   * Serializer for scala.Enumeration by name.
   */
  implicit def enumNameWrites[E <: Enumeration]: Writes[E#Value] = new Writes[E#Value] {
    def writes(value: E#Value): JsValue = JsString(value.toString)
  }

}