Play Framework Scala format large JSON (No unapply or unapplySeq function found)

Question

I need to receive a big JSON on my server (more than 22 fields). I have a case class with a lot of fields:

case class Filters(objectType: Option[String] = None,
     deal: Option[String] = None,
     roomsCount: Option[String] = None,
     region: Option[Int] = None,
     district: Option[Int] = None,
     direction: Option[Int] = None
     ...
)

And JSON format function in controller:

implicit val filtersFormat = Json.format[Filters]

At compilation I have error:

[error] WebSockets.scala:18: No unapply or unapplySeq function found
[error]   implicit val filtersFormat = Json.format[Filters]
[error]                                          ^

Is there a way to solve the problem without breaking JSON to small parts?

Answer 1

I did it this way:

case class Filters(part1: Part1, part2: Part2, ...)

case class Part1(
    field1: Field1,
    field2: Field2,
    ...
    field10: Field10,
)

object Part1 {
    implicit val part1Format = Json.format[Part1]
}

...

object Filters {
    implicit val filtersReads = (
        JsPath.read[Part1] and
        JsPath.read[Part2] and
        ...
    )(Filters.apply _)

    implicit val filtersWrites = (
        JsPath.write[Part1] and
        JsPath.write[Part2] and
        ...
    )(unlift(Filters.unapply))
}

Answer 2

As @Sawyer mentioned you can use an external library. This was taken from this blog.

First add the lib dependency to your SBT

libraryDependencies += "ai.x" %% "play-json-extensions" % "0.42.0"

Then you can use it like this:

import ai.x.play.json.Jsonx
import play.api.libs.json.{Json, OFormat}

case class Foo(a1: String, a2: String, a3: String, a4: String, a5: String,
               a6: String, a7: String, a8: String, a9: String, a10: String,
               a11: String, a12: String, a13: String, a14: String, a15: String,
               a16: String, a17: String, a18: String, a19: String, a20: String,
               a21: String, a22: String, a23: String)

object Foo {
  implicit val f: OFormat[Foo] = Jsonx.formatCaseClass[Foo]
}