如何在Throwable Scala对象中获取数据？

Question

How I get information inside a Throwable Scala object?

The code is an example about throwable.getMessage .

JsResultException(errors:List((,List(JsonValidationError(List('eoh' is undefined on object: {"store":"8767565","sku":"1983278364782364782"}),WrappedArray())))))

I need to extract JsResultException , JsonValidationError as string, message 'eoh' is undefined on object message and JSON before object: .

Is this for make graceful log.

Answer 1

Consider converting JsResultException.errors which is

Seq[(JsPath, Seq[JsonValidationError])]

where JsonValidationError.errors is yet another sequence Seq[String] , into a simpler tuple

Seq[(JsPath, String)]

like so

case JsResultException(errors) =>
  errors.map { case (path, validationErrors) => path -> validationErrors.map(_.messages.mkString(",")).mkString(",") }

This would produce a more managable structure similar to

List((/id,error.path.missing), (/name,error.path.missing))

instead of

List((/id,List(JsonValidationError(List(error.path.missing),WrappedArray()))), (/name,List(JsonValidationError(List(error.path.missing),WrappedArray())))))]

Here is a working example

case class User(name: String, id: Int)
object User {
  implicit val formats = Json.format[User]
}

val raw = """{ "nam": "mario", "i": 5 }"""

try {
  Json.parse(raw).as[User]
} catch {
  case JsResultException(errors) =>
    errors.map { case (path, validationErrors) => path -> validationErrors.map(_.messages.mkString(",")).mkString(",") }
}

Also consider using validation to avoid throwing exceptions like so

Json.parse(raw).validate[User] match {
  case s: JsSuccess[User] => s
  case JsError(errors) => 
    errors.map { case (path, validationErrors) => path -> validationErrors.map(_.messages.mkString(",")).mkString(",") }
}

Answer 2

You can always use the scala.util.Try and pattern match the Failure.

import scala.util._

def someExceptionThrowingMethod(): T = ???

Try(someExceptionThrowingMethod()) match {
    case Success(t: T) => ???
    case Failure(exception: Throwable) => exception match {
        case JsResultException((_, JsonValidationError(headMessage :: _) :: _, _) :: _) => 
          //here headMessage is the 'eoh' is undefined on object: {"store":"8767565","sku":"1983278364782364782"} message you wrote above
        case otherException: Throwable => ???
    }
}