spray-json Cannot find JsonWriter or JsonFormat type class for Class - scala

Question

I still get the same error, I have defined the marshaller (and imported it); it appears that the case class entry is not in context when the function is polymorphic. and this throws a Cannot find JsonWriter or JsonFormat type class for Case Class. Is there a reason why spray-json can not find the implicit marshaller for the case class, (even when defined) is this case class in context? Link to marshaller
import spray.json._
import queue.MedusaJsonProtocol._
object MysqlDb {
...
}
case class UserDbEntry(
id: Int,
username: String,
countryId: Int,
created: LocalDateTime
)
trait MysqlDb {
implicit lazy val pool = MysqlDb.pool
}
trait HydraMapperT extends MysqlDb {
val FetchAllSql: String
def fetchAll(currentDate: String): Future[List[HydraDbRow]]
def getJson[T](row: T): String
}
object UserHydraDbMapper extends HydraMapperT {
override val FetchAllSql = "SELECT * FROM user WHERE created >= ?"
override def fetchAll(currentDate: String): Future[List[UserDbEntry]] = {
pool.sendPreparedStatement(FetchAllSql, Array(currentDate)).map { queryResult =>
queryResult.rows match {
case Some(rows) =>
rows.toList map (x => rowToModel(x))
case None => List()
}
}
}
override def getJson[UserDbEntry](row: UserDbEntry): String = {
HydraQueueMessage(
tableType = HydraTableName.UserTable,
payload = row.toJson.toString()
).toJson.toString()
}
private def rowToModel(row: RowData): UserDbEntry = {
UserDbEntry (
id = row("id").asInstanceOf[Int],
username = row("username").asInstanceOf[String],
countryId = row("country_id").asInstanceOf[Int],
created = row("created").asInstanceOf[LocalDateTime]
)
}
}
payload = row.toJson.toString() Can't find marshaller for UserDbEntry

Answer 1

You have defined UserDbEntry locally and there is no JSON marshaller for that type. Add the following:
implicit val userDbEntryFormat = Json.format[UserDbEntry]
I'm not sure how you can call row.toJson given UserDbEntry is a local case class. There must be a macro in there somewhere, but it's fairly clear that it's not in scope for the local UserDbEntry.
Edit
Now that I see your Gist, it looks like you have a package dependency problem. As designed, it'll be circular. You have defined the JSON marshaller in package com.at.medusa.core.queue, which imports UserDbEntry, which depends on package com.at.medusa.core.queue for marshalling.