emmea90 emmea90 - 13 days ago 6
JSON Question

Scala + Play Framework + Slick - Json as Model Field

I need to save a Json Field as a column of my Play Framework Model. My table parser in DAO is

class Table(tag: Tag) extends Table[Model](tag, "tablename") {
implicit val configFormat = Json.format[Config]

// Fields ...
def config = column[Config]("config", O.SqlType("JSON"))
// Fields ...

}


Config
is defined as a case class in Model in Play Model folder and has his companion object. Field of this object are Int, Double or String

case class Config ( // fields )

object Config {
implicit val readConfig: Reads[Config] = new Reads[Config]
for {
// fields
} yield Config(// fields)

implicit val configFormat = Json.format[Config]

}


Problem is i can't compile due to this error

Error:(28, 37) could not find implicit value for parameter tt:
slick.ast.TypedType[models.Config]
def config = column[Config]("config", O.SqlType("JSON"))


Is there a way to save the Config model as Json in the Table (reading it as Config)?

Answer

You need to tell Slick how to convert your Config instances into database columns:

implicit val configFormat = Json.format[Config]
implicit val configColumnType = MappedColumnType.base[Config, String](
  config => Json.stringify(Json.toJson(config)), 
  column => Json.parse(column).as[Config]
)