No instance of play.api.libs.json.Format is available for scala.Char in the implicit scope

Question

I have a case class:

case class Status(cmpId: String, stage: String, status: String, outputPath: String, message: String, delimiter: Char = ',')

I am using : "com.typesafe.play" %% "play-json" % "2.7.2"

and have written below formats:

implicit val formats = DefaultFormats

implicit val emStatusFormat =Json.format[EmStatus]

but still getting an error:

 No instance of play.api.libs.json.Format is available for scala.Char in the implicit scope

Can anyone help me resolve this issue.

Answer 1

You try to convert this format:

Status("cmpId value", "stage value", "status value", "outputPath value", "message value", ',')

into JSON.

Play JSON (with format generation) would like it be converted into:

{
  "cmpId": "cmpId value",
  "stage": "stage value",
  "status": "status value",
  "outputPath": "outputPath value",
  "message": "message value",
  "delimiter": ???
}

Exactly - how should Char be encoded? Is it a single character String? Is it an integer of 1 byte size? There is no common convention for this, which is why Play JSON didn't provided any codec for it.

But you can:

import play.api.libs.json.Format
implicit val charFormat: Format[Char] = ... // your implementation

Once you provide it, compilation will succeed.

You can:

• write it by hand:

  implicit val charFormat: Format[Char] = new Format[Char]{
    /* implement required methods */
  }
  

• use another codec to generate it

  import play.api.libs.functional.syntax._
  implicit val charFormat: Format[Char] = implicitly[Format[String]].inmap[Char](_.head, _.toString)