playframework scala slick how many attributes are allowed - scala

Question

In my Playframework scala application I have the following model:
case class ProcessTemplatesModel(
id: Option[Int] = None,
title: String,
version: String,
createdat: Option[String],
updatedat: Option[String],
deadline: Option[Date],
status: Option[String],
comment: Option[String],
checked: Option[Boolean],
checkedat: Option[Date],
approved: Option[Boolean],
approvedat: Option[Date],
deleted: Boolean,
approveprocess: Int,
trainingsprocess: Option[Int],
previousVersion: Option[Int],
originTemplate: Option[Int],
client: Int,
approveProcessInstance: Option[Int],
responsible: Option[Seq[UserModel]],
accountable: Option[Seq[UserModel]],
consulted: Option[Seq[UserModel]],
informed: Option[Seq[UserModel]])
object ProcessTemplatesModel {
implicit val processFormat = Json.format[ProcessTemplatesModel]
}
Today I added the approveProcessInstance: Option[Int],
Now I got this error while it compiles: No unapply or unapplySeq function found ... on this line: implicit val processFormat = Json.format[ProcessTemplatesModel]
Why does this fail in this case?

Answer 1

22 values is a max in play JSON, you can use 3rd party libraries to increase the number.
Here the issue thread in the Play source:
https://github.com/playframework/playframework/issues/3174
One of the possible solution:
https://github.com/xdotai/play-json-extensions
Example from my build.sbt
libraryDependencies ++= Seq(
cache,
filters,
ws,
// More than 22 fields in Json
"ai.x" %% "play-json-extensions" % "0.8.0"
)
For Play 2.6 you need to use version 10:
"ai.x" %% "play-json-extensions" % "0.10.0"
Then, in the file with JSON:
import ai.x.play.json.Jsonx
implicit val processFormat = Jsonx.formatCaseClass[ProcessTemplatesModel]
More details: https://github.com/xdotai/play-json-extensions#create-explicit-formatter

Answer 2

One other idea would be to decompose the model into fine grained models and have a composition of it. This way, you do not have to import yet another library!