What JSON library to use in Scala

Question

I need to build a JSON string  something like this          id   1   name    John         id   2   name    Dani      val jArray   JsArray    jArray       id    1      name    John    jArray       id    2      name    Dani    println jArray dump    I need to be able to add rows to the jArray  something like jArray         What is the closest library solution to this

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Jawn is a very flexible JSON parser library in Scala. It also allows generation of custom ASTs; you just need to supply it with a small trait to map to the AST.

Worked great for a recent project that needed a little bit of JSON parsing.

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Let me also give you the SON of JSON version   import nl typeset sonofjson    arr    obj id   1  name    John    obj id   2  name    Dani

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Rapture seems to be missing in the list of the answers  It can be obtained from http   rapture io  and allows you  among other thing  to    select JSON back-end  which is very useful if you already use one  in import  decide if you work with Try  Future  Option  Either  etc   also in import  do a lot of work in a single line of code    I don t want to copy paste Rapture examples from it s page  A nice presentation about Rapture s features was given by Jon Pretty at SBTB 2014  https   www youtube com watch v ka5-OLJgybI

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Lift-json is at version 2 6 and it works really well  and is also very well supported  the maintainer is always ready to fix any bugs users may find  You can find examples using it on the github repository  The maintainer  Joni Freeman  is always reachable on the Lift mailing list  There are also other users on the mailing list  who are very helpful as well   As  Alexey points out  if you want to use the library with other Scala version  say 2 11 x  change scalaVersion and use    as follows   scalaVersion     2 11 5     net liftweb      lift-json     2 6    You can check the liftweb net site to find out the latest version as time goes by

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I use uPickle which has the big advantage that it will handle nested case classes automatically   object SerializingApp extends App      case class Person name  String  address  Address     case class Address street  String  town  String  zipCode  String     import upickle default      val john   Person  John Doe   Address  Elm Street 1    Springfield    ABC123       val johnAsJson   write john       Prints   name   John Doe   address    street   Elm Street 1   town   Springfield   zipCode   ABC123      Console println johnAsJson        Parse the JSON back into a Scala object   Console println read Person  johnAsJson         Add this to your build sbt to use uPickle   libraryDependencies     com lihaoyi      upickle     0 4 3

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Play released its module for dealing with JSON independently from Play Framework  Play WS  Made a blog post about that  check it out at http   pedrorijo com blog scala-json   Using case classes  and Play WS  already included in Play Framework  you case convert between json and case classes with a simple one-liner implicit  case class User username  String  friends  Int  enemies  Int  isAlive  Boolean   object User     implicit val userJsonFormat   Json format User

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I use PLAY JSON library you can find the mavn repo for only the JSON library not the whole framework here      val json    com typesafe play      play-json    version     val typesafe    typesafe com  at  http   repo typesafe com typesafe releases     A very good tutorials about how to use them  are available here   http   mandubian com 2012 09 08 unveiling-play-2-dot-1-json-api-part1-jspath-reads-combinators   http   mandubian com 2012 10 01 unveiling-play-2-dot-1-json-api-part2-writes-format-combinators   http   mandubian com 2012 10 29 unveiling-play-2-dot-1-json-api-part3-json-transformers

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Unfortunately writing a JSON library is the Scala community s version of coding a todo list app   There are quite a variety of alternatives  I list them in no particular order  with notes    parsing json JSON - Warning this library is available only up to Scala version 2 9 x  removed in newer versions  spray-json - Extracted from the Spray project Jerkson    - Warning a nice library  built on top of Java Jackson  but now abandonware  If you are going to use this  probably follow the Scalding project s example and use the backchat io fork sjson - By Debasish Ghosh lift-json - Can be used separately from the Lift project json4s        - An extraction from lift-json  which is attempting to create a standard JSON AST which other JSON libraries can use  Includes a Jackson-backed implementation Argonaut     - A FP-oriented JSON library for Scala  from the people behind Scalaz play-json    - Now available standalone  see this answer for details dijon - A handy  safe and efficient JSON library  uses jsoniter-scala under hood  sonofjson - JSON library aiming for a super-simple API Jawn - JSON library by Erik Osheim aiming for Jackson-or-faster speed Rapture JSON    - a JSON front-end which can use 2  4  5  6  7  11 or Jackson as back-ends circe  - fork of Argonaut built on top of cats instead of scalaz jsoniter-scala - Scala macros for compile-time generation of ultra-fast JSON codecs jackson-module-scala - Add-on module for Jackson to support Scala-specific datatypes borer - Efficient CBOR and JSON  de serialization in Scala      has not fixed security vulnerabilities       has Scalaz integration       supports interop with Jackson JsonNode  In Snowplow we use json4s with the Jackson back-end  we ve had good experiences with Argonaut too

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I suggest using jerkson  it supports most basic type conversions   scala gt  import com codahale jerkson Json    scala gt  val l   List                    Map   id  - gt  1   name  - gt   John                      Map   id  - gt  2   name  - gt   Dani                     scala gt  generate  l    res1  String      id  1  name   John     id  2  name   Dani

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You should check Genson  It just works and is much easier to use than most of the existing alternatives in Scala  It is fast  has many features and integrations with some other libs  jodatime  json4s DOM api       All that without any fancy unecessary code like implicits  custom readers writers for basic cases  ilisible API due to operator overload     Using it is as easy as   import com owlike genson defaultGenson   val json   toJson Person Some  foo    99   val person   fromJson Person       name    foo    age   99       case class Person name  Option String   age  Int    Disclaimer  I am Gensons author  but that doesn t meen I am not objective

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You can try this  https   github com momodi Json4Scala  It s simple  and has only one scala file with less than 300 lines code   There are samples   test  base         assert Json parse  123   asInt    123      assert Json parse  -123   asInt    -123      assert Json parse  111111111111111   asLong    111111111111111l      assert Json parse  true   asBoolean    true      assert Json parse  false   asBoolean    false      assert Json parse  123 123   asDouble    123 123      assert Json parse    aaa     asString     aaa       assert Json parse    aaa     write         aaa          val json   Json Value Map  a  - gt  Array 1 2 3    b  - gt  Array 4  5  6        assert json  a   0  asInt    1      assert json  b   1  asInt    5    test  parse base         val str                           int  -123   long   111111111111111   string   asdf    bool true   true   foo   foo    bool false   false                  val json   Json parse str      assert json asMap  int   asInt    -123      assert json asMap  long   asLong    111111111111111l      assert json asMap  string   asString     asdf       assert json asMap  bool true   asBoolean    true      assert json asMap  bool false   asBoolean    false      println json write        assert json write   length  gt  0    test  parse obj         val str                            asdf   1 2 4   bbb   ttt   432                   val json   Json parse str      assert json asMap  asdf   asArray 0  asInt    1      assert json asMap  asdf   asArray 3  asMap  bbb   asString     ttt     test  parse array         val str                           1 2 3 4   a   1 2 3                    val json   Json parse str      assert json asArray 0  asInt    1      assert json 4   a   2  asInt    3      assert json 4   a   2  isInt      assert json 4   a   isArray      assert json 4   a   isMap    false    test  real         val str       styles    214776380871671808 214783111085424640 214851869216866304 214829406537908224    group   100   name     AO4614                           shopgrade   8   price   0 59   shop id   60095469   C3   50018869   C2   50024099   C1   50008090   imguri     http   img geilicdn com taobao10000177139 425x360 jpg     cag   50006523   soldout   0   C4   50006523       val json   Json parse str      println json write        assert json asMap size  gt  0

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AlaxDean s  7 answer  Argonaut is the only one that I was able to get working quickly with sbt and intellij  Actually json4s also took little time but dealing with a raw AST is not what I wanted  I got argonaut to work by putting in a single line into my build st    libraryDependencies     io argonaut      argonaut     6 0 1    And then a simple test to see if it I could get JSON   package mytest   import scalaz    Scalaz   import argonaut    Argonaut    object Mytest extends App      val requestJson                         userid    1                stripMargin    val updatedJson  Option Json    for       parsed  lt - requestJson parseOption     yield   name   jString  testuser    - gt   parsed    val obj   updatedJson get obj   printf  Updated user   s n   updatedJson toString      printf  obj    s n   obj toString      printf  userid   s n   obj get toMap  userid        And then     sbt  gt  run Updated user  Some   userid   1   name   testuser    obj   Some object   userid   1     name   testuser     userid   1    Make sure you are familiar with Option which is just a value that can also be null  null safe I guess   Argonaut makes use of Scalaz so if you see something you don t understand like the symbol     an or operation  it s probably Scalaz

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Number 7 on the list is Jackson  not using Jerkson  It has support for Scala objects   case classes etc    Below is an example of how I use it   object MyJacksonMapper extends JacksonMapper val jsonString   MyJacksonMapper serializeJson myObject  val myNewObject   MyJacksonMapper deserializeJson MyCaseClass  jsonString    This makes it very simple  In addition is the XmlSerializer and support for JAXB Annotations is very handy    This blog post describes it s use with JAXB Annotations and the Play Framework   http   krasserm blogspot co uk 2012 02 using-jaxb-for-xml-and-json-apis-in html  Here is my current JacksonMapper   trait JacksonMapper      def jsonSerializer         val m   new ObjectMapper       m registerModule DefaultScalaModule      m        def xmlSerializer         val m   new XmlMapper       m registerModule DefaultScalaModule      m        def deserializeJson T  Manifest  value  String   T   jsonSerializer readValue value  typeReference T     def serializeJson value  Any    jsonSerializer writerWithDefaultPrettyPrinter   writeValueAsString value    def deserializeXml T  Manifest  value  String   T   xmlSerializer readValue value  typeReference T     def serializeXml value  Any    xmlSerializer writeValueAsString value     private this  def typeReference T  Manifest    new TypeReference T        override def getType   typeFromManifest manifest T          private this  def typeFromManifest m  Manifest      Type          if  m typeArguments isEmpty    m erasure        else new ParameterizedType          def getRawType   m erasure         def getActualTypeArguments   m typeArguments map typeFromManifest  toArray         def getOwnerType   null

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Here is a basic implementation of writing and then reading json file using json4s   import org json4s   import org json4s jackson JsonMethods   import org json4s JsonDSL   import java io   import scala io Source   object MyObject   def main args  Array String        val myMap   Map  a  - gt  List 3 4    b  - gt  List 7 8         writing a file    val jsonString   pretty render myMap      val pw   new PrintWriter new File  my json json      pw write jsonString    pw close         reading a file    val myString   Source fromFile  my json json   mkString   println myString     val myJSON   parse myString     println myJSON        Converting from JOjbect to plain object   implicit val formats   DefaultFormats   val myOldMap   myJSON extract Map String  List Int       println myOldMap

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Maybe I ve late a bit  but you really should try to use json library from play framework  You could look at documentation  In current 2 1 1 release you could not separately use it without whole play 2  so dependency will looks like this   val typesaferepo     TypeSafe Repo  at  http   repo typesafe com typesafe releases  val play2    play      play     2 1 1    It will bring you whole play framework with all stuff on board    But as I know guys from Typesafe have a plan to separate it in 2 2 release  So  there is standalone play-json from 2 2-snapshot

[json] What JSON library to use in Scala?

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