README

jacks - Jackson module for Scala

  Jacks provides a Jackson Module for reading and writing common Scala data
  types, including mutable & immutable collections, Option, Tuple, Symbol,
  and case classes.

  This version of jacks has been tested against Scala 2.9.3, 2.10.2 and
  Jackson 2.2.2

  Join the lambdaWorks-OSS Google Group to discuss this project:

    http://groups.google.com/group/lambdaworks-oss
    lambdaworks-oss@googlegroups.com

Basic Usage

  The JacksMapper companion object provides a preconfigured ObjectMapper
  and a number of read/write methods:

  JacksMapper.writeValueAsString(List(1, 2, 3)) == "[1,2,3]"

  JacksMapper.readValue[List[Int]]("[1, 2, 3]") == List(1, 2, 3)

  The preconfigured ObjectMapper is available via JacksMapper.mapper
  and a new ScalaModule may be added to any existing ObjectMapper.

Erasure & Manifests

  Reading parameterized types requires a Jackson JavaType which can be
  derived from a Scala Manifest. The readValue methods of JacksMapper take
  an implicit Manifest and look up the appropriate JavaType.

  JacksMapper.resolve(manifest) will also return the correct JavaType
  given a Manifest.

Serialization Details

  Maps are serialized as JSON objects, Seqs and Sets are serialized as
  JSON arrays. Tuples are also serialized as JSON arrays.

  None is serialized as null, Some(v) is serialized as v.

  Symbols are serialized as strings.

  Case classes are serialized as JSON objects.

Collections

  Jacks supports bidirectional mapping of nearly all Scala mutable and
  immutable collections. Custom collections types are also supported as
  long as they implement a supported interface and provide the
  appropriate companion object.

Case Classes

  Jacks supports bidirectional mapping of case classes as JSON objects,
  with a few restrictions: a ScalaSig is required, only fields declared
  in the primary constructor are included, and inherited members are
  ignored.

  Jackson supports a rich set of annotations for modifying the default
  (de)serialization of standard classes and their fields. Jacks will
  not support all of these annotations for case classes, but does
  support the following:

    @JsonProperty, @JsonIgnore, @JsonIgnoreProperties, @JsonInclude
    @JsonCreator

  Jacks normally instantiates case classes via their primary constructor.
  Alternatively a method of the companion object may be used instead by
  annotating it with @JsonCreator and ensuring that each method parameter
  is annotated with @JsonProperty:

    sealed trait AB { @JsonValue def jsonValue: String }
    case object A extends AB { def jsonValue = "A" }
    case object B extends AB { def jsonValue = "B" }

    object Editor extends Enumeration {
      val vi, emacs = Value
    }

    case class KitchenSink[T](foo: String, bar: T, v: AB, ed: Editor.Value)

    object KitchenSink {
      @JsonCreator
      def create[T](
        @JsonProperty("foo") foo: String,
        @JsonProperty("bar") bar: T,
        @JsonProperty("v")   v:   String = "A",
        @JsonProperty("ed")  ed:  String = "emacs"
      ): KitchenSink[T] = KitchenSink[T](foo, bar, if (v == "A") A else B, Editor.withName(ed))
    }

Maven Artifacts

  Releases of jacks are available in the maven central repository:

  "com.lambdaworks" %% "jacks" % "2.2.3"

  <dependency>
    <groupId>com.lambdaworks</groupId>
    <artifactId>jacks_2.10</artifactId>
    <version>2.2.3</version>
  </dependency>