scala - upickle gives a ScalaReflectionException when writing a case class -

i have simple case class:

object margin {   def apply(top: int, right: int, bottom: int, left: int): margin = {     margin(some(top), some(right), some(bottom), some(left))   } }  case class margin(top: option[int], right: option[int], bottom: option[int], left: option[int]) 

when calling upickle.write on instance of above class, following exception:

scala.scalareflectionexception: value apply encapsulates multiple      overloaded alternatives , cannot treated method. consider  invoking `<offending symbol>.asterm.alternatives` , manually picking  required method 

what error message mean , how fix it?

the above error message result of margin class having multiple overloaded apply methods. first 1 case class constructor, , other in companion object. upickle not know apply method use , throws exception. known limitation.

one workaround rename apply method in companion object. write custom pickler.

here clumsy version of custom pickler solved problem:

object margin {   def create(top: int, right: int, bottom: int, left: int): margin = {     margin(some(top), some(right), some(bottom), some(left))   }    implicit val marginwriter = upickle.writer[margin]{     case m =>       js.obj(fields(m).map(kv => (kv._1, js.num(kv._2))):_*).asinstanceof[js.value]   }    implicit val marginreader = upickle.reader[margin]{     case obj: js.obj =>       val map = obj.value.tomap       margin(map.get("top").map(_.value.asinstanceof[int]),         map.get("right").map(_.value.asinstanceof[int]),         map.get("bottom").map(_.value.asinstanceof[int]),         map.get("left").map(_.value.asinstanceof[int]))   }    private def fields(m: margin) = seq(m.top.map(("top", _)), m.right.map(("right", _)), m.bottom.map(("bottom", _)),     m.left.map(("left", _))).flatten }