How to read json array in scala using the Play framework

Question

I have the following Json as var dataObject ={"files": ["code.R", "data.cv", "input.txt"]}. I am posting this json as a body from the client side and I want to parse the Json and read these files names in the server side in play scala.

Please help

Tomer · Accepted Answer · 2017-11-29 15:16:31Z

1

Because you have only one field, you can't use json combinators, But you can do as follow:

case class Selection(files:List[String])
object Selection{
   implicit val selectionReads = (__ \ 'files).read[List[String]].map{ l => Selection(l) }
   implicit val selectionWrites = (__ \ 'files).write[List[String]].contramap { (selection: Selection) => selection.files}

   //You can replace the above 2 lines with this line - depends on you.
   implicit val selectionFormat: Format[Selection] = (__ \ 'files).format[List[String]].inmap(files => Selection(files), (selection: Selection) => selection.files)
}

Make sure you import:

import play.api.libs.functional.syntax._

edited Nov 29, 2017 at 15:16

answered Dec 25, 2015 at 13:54

Tomer

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3 Comments

sanmoy paul Over a year ago

how to print the selected file names

Tomer Over a year ago

Json.stringify(Json.toJson(Selection(List("x","y","z")))) @sanmoypaul

dirceusemighini Over a year ago

Hey @Tomer there is a little mistype in the first word of your answer.

znurgl · Accepted Answer · 2015-12-24 16:30:09Z

0

This is the documentation: https://www.playframework.com/documentation/2.5.x/ScalaJson

And the solution is simple:

import play.api.libs.json._

val json: JsValue = Json.parse("{ "files": ["code.R","data.csv","input.txt"] }")

val files = (json \ "files").get

answered Dec 24, 2015 at 16:30

znurgl

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3 Comments

sanmoy paul Over a year ago

The array is dynamic it comes from check box selection as a result i dnt know the filenames before hand

sanmoy paul Over a year ago

Please show an example how to do in this type of case

znurgl Over a year ago

In that case you need a JsonBodyParser: playframework.com/documentation/2.5.x/JavaBodyParsers

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