How to convert json file to List using scala


How to convert json file to List using scala



I have the following json input
sample.json


[{"level": 1, "firstFile": "one", "secondFile": "first"},
{"level": 1, "firstFile": "two", "secondFile": "sec"},
{"level": 2, "firstFile": "three", "secondFile": "third"}]



i want my result should be:


val first= List(List("one","two"),List("three"))
val second= List(List("first","sec"),List("third"))



build.sbt:


name := "Test"
version := "1.0"
scalaVersion := "2.11.0"

libraryDependencies ++= Seq("org.apache.spark" % "spark-sql_2.11" % "2.0.0" % "provided")
libraryDependencies += "com.typesafe" % "config" % "1.2.0"
libraryDependencies ++= Seq("org.slf4j" % "slf4j-api" % "1.7.5",
"org.clapper" %% "grizzled-slf4j" % "1.3.1")
libraryDependencies += "ch.qos.logback" % "logback-core" % "1.2.3"
libraryDependencies += "ch.qos.logback" % "logback-classic" % "1.2.3" % "test"
libraryDependencies += "com.databricks" % "spark-avro_2.11" % "4.0.0"
libraryDependencies += "io.circe" %% "circe-config" % "0.4.1"
retrieveManaged := true




2 Answers
2



Usually you convert JSON to case classes using a library like Jackson or Circe.


val json = """[{"level": 1, "firstFile": "one", "secondFile": "first"},
| {"level": 1, "firstFile": "one", "secondFile": "first"},
| {"level": 2, "firstFile": "two", "secondFile": "sec"},
| {"level": 2, "firstFile": "two", "secondFile": "sec"}]""".stripMargin

case class My2FileThing(level: Int, firstFile: String, secondFile: String)

val parsed: List[My2FileThing] = {
// TODO parse json using some library; there are many available

List(
My2FileThing(1, "one", "first"),
My2FileThing(1, "one", "first"),
My2FileThing(2, "two", "sec"),
My2FileThing(2, "two", "sec")
)
}



The json you provided is a one dimensional List containing four of these items, as above.


List



To transform that data into the two Lists you asked for, you can do this, I guess. You have not told us the logic behind your transformation.


val firstLineChandraWants: List[List[String]] =
parsed.map(_.firstFile).groupBy(identity).values.toList
val secondLineChandraWants: List[List[String]] =
parsed.map(_.secondFile).groupBy(identity).values.toList





Thanks for the reply. could you please help me how to parse the JSON.
– Chandra
yesterday



Use some library for converting the Json String to a Scala object/type.



For more info: How to convert JSON to a type in Scala



Example using Lift:


import net.liftweb.json._
implicit val formats = DefaultFormats // Brings in default date formats etc.
val json = """
[{"level": 1, "firstFile": "one", "secondFile": "first"},
{"level": 1, "firstFile": "two", "secondFile": "sec"},
{"level": 2, "firstFile": "three", "secondFile": "third"}]
"""
case class ListSubType(level: Int, firstFile: String, secondFile: String)

val parsed: List[ListSubType] = parse(json).extract[List[ListSubType]]
val desired: List[List[String]] = parsed.map(a => List(a.firstFile, a.secondFile))

// will produce: List(List("one", "first"), List("two", "sec"), List("three", "third"))



I know you asked different elements(of root list) in different variables, but it's better to use index or iterate over list than using different variables. Practically length of list is indefinite, so how are you gonna assign different items to different variables.
Example=>


/**
* Using index
*/
val first:Option[String] = desired.get(0) // will return Option[String]
val second:Option[String] = desired.get(1) // will return Option[String]

for (items <- desired) {
println(items)
}



Use this link to get import code for your desired build tool/package manger.



https://search.maven.org/#artifactdetails%7Cnet.liftweb%7Clift-json%7C2.0%7Cjar





I am getting error at import net.liftweb.json._ object liftweb is not a member of package net
– Chandra
Jun 30 at 3:39





@Chandra see the edit
– Ravinder Payal
2 days ago





@ Ravinder Payal thanks for the reply. I added libraryDependencies += "net.liftweb" %% "lift-json" % "2.4-M5" but while running the sbt i am getting error. [error] (*:update) sbt.ResolveException: unresolved dependency: net.liftweb#lift-json_2.11;2.4-M5: not found [error] Could not create Eclipse project files: [error] [Error evaluating task 'scalacOptions': error,Error evaluating task 'externalDependencyClasspath': error,Error evaluating task 'update': error,Error evaluating task 'updateClassifiers': error,Error evaluating task 'updateClassifiers': error]. Any other help?
– Chandra
yesterday





@Chandra Share your sbt file as a question edit, it seems you haven't mapped any central repository in your build.sbt
– Ravinder Payal
yesterday






added the buid.sbt file. please suggest.
– Chandra
23 hours ago






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