How to Manipulate JSON AST in Scala -

I am experimenting with the json4s library (based on lift-jsn). I'm one of those things to parse a JSON string in AST, and then manipulate it. For example, I want to upset a field (put the field in AST if it does not exist, or update its value if it does so).

I have not figured out how to do this in the document. Experiment with available methods, I came up with the following, which works but seems unnecessary.

  import org.json4s._ import org.json4s.JsonDSL._ import org.json4s Basic. JasonMedish._Object TestJason {Intimate Val Format = Default Format DIF Main (Args: Array [String]): Unit = {Wall Jason = "" {"FU": 1, "Bar": {"Foo": 2}} " "" Atl et pars (jsn) .asInstanceOf [Jobbject] println (upsertField (ast, ("foo" -> "3")) println (upsertField (ast, ("foobar" -> "3 ") () ())}} Def upsertField (src: Jobbject, fld: JField): jvvu = {if (src \ fld._1 == JNothing) {src ~ fld} else {src.replace (list (fld._1), many For reasons I dislike:  
 
  To explicitly insert the results of pars (JSN)   
 / cod E> to  jabax   
 The result of the  upsertfield  function is a  JValue  for which I must reload the object I want to manipulate  
 The  upsertfield  function just feels         
 
 
 Merge function that creates or overrides a field, you can also update the fields that are not at the root level of the tree.  
  import org.json4s._ import org.json4s.JsonDSL._ import org.json4s.jackson.JsonMethods._Object mergeson app {val Json = "" "| {|" Foo ": 1, |" Bar ": {|" Foo ": 2 |} |} |" Expands "" ".stripMargin val ast = parse (json) val update = ast merge ((" foo ", 3) ~ (" bar ", (" fnord ", 5)) println (beautiful) / {// "Foo": 3, // "bar": {// "foo": 2, // "fnord": 5 //}}}    / Html>