README.md

json-macro

json-macro is an attempt at a scalameta macro for play-json that avoids the overhead of play-json's functional syntax. See this blog post for details.

Compatibility is currently tested against play-json 2.6.0-M1. That means it is compatible with play-json 2.5.x as well but that is mostly incidental. Once 2.6.x becomes final I plan to support the latest stable release of play-json moving forward. Any version that has the same Reads/Writes API should automatically be supported by json-macro.

Install

Add the follow to your build.sbt:

resolvers += Resolver.bintrayRepo("gregghz", "gregghz")

addCompilerPlugin("org.scalameta" % "paradise" % "3.0.0-beta4" cross CrossVersion.full)

libraryDependencies += "com.gregghz" %% "json-macro" % "0.1.0"

Usage

In contrast with Play's Json.format[A] macro, json-macro has to use an annotation until #160 is resolved:

import com.gregghz.json._

@JsonRecord
case class Thing(a: String)

This will expand into roughly the following code:

case class Thing(a: String)
object Thing {
  implicit val reads: Reads[Thing] = Reads[Thing] { json =>
    for {
      a <- (json \ "a").validate[String]
    } yield Thing(a)
  }

  implicit val writes: Writes[Thing] = Writes[Thing] { obj =>
    Json.obj(
      "a" -> obj.a
    )
  }
}

You can also override the keys used in the serialized json:

import com.gregghz.json._

@JsonRecord
case class Thing(a: String ~ hello)

This will expand into the following:

case class Thing(a: String)
object Thing {
  implicit val reads: Reads[Thing] = Reads[Thing] { json =>
    for {
      a <- (json \ "hello").validate[String]
    } yield Thing(a)
  }

  implicit val writes: Writes[Thing] = Writes[Thing] { obj =>
    Json.obj(
      "hello" -> obj.a
    )
  }
}