uPickle does not handle BigDecimal?

[SemanticBeeng .]

Hi,

Getting "uPickle does not know how to write " errors for some case classes using BigDecimal.

Is there a way around this by writing a BigDecimal format or must I write a format for every class containing BigDecimal?

Thanks

Nick

[Haoyi Li]

Yep, uPickle doesn't support BigDecimal.

Neither does Scala.js though https://github.com/scala-js/scala-js/issues/373

You can easily write your own format for BigDecimal to make it work on the JVM, but for Scala.js you'll need to implement it.

No need to do it for every class, just BigDecimal itself is sufficient.

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[SemanticBeeng]

Hi,

Now the BigDecimal is supported (thanks!) in SJS 0.6.3 it is possible to make uPickle work with BigDecimal

 object BigDecimalFormat {

    val nothing = ""

    implicit val bigDecimal2Writer = upickle.Writer[BigDecimal] {

      case t => Js.Str("" + t)

    }

    implicit val bigDecimal2Reader = upickle.Reader[BigDecimal] {

      case Js.Str(str) => BigDecimal(str)

    }

  }

It is just that one needs to explicitly import BigDecimalFormat._ by hand wherever needed.

Intellij thinks it is unused and auto optimizes it away (annoying).

Is there a better way?

Thanks

Nick

[Benjamin Jackman]

You could put that into a trait you mix into your package objects. Then you won't have to import it.

You will have to deal with chained package clauses / base packages if the package object is up 

the hierarchy from your file.

In general for implicits I prefer a style where library makers write their code in such a way that I can mix their exports in via a trait to my package objects so that I don't have to say import somelib._ everywhere. Usually they just write an object that contains all their exports, however if they put them into a trait they could still just have the eponymous object mix it in, and clients would also have the option to simply mix it the trait into their package objects if they set their projects up that way, or

just use the import someObject._ style if they prefer (small projects).

[Benjamin Jackman]

to clarify i'd have structured the code like this

 trait BigDecimalFormat {

    val nothing = ""

    implicit val bigDecimal2Writer = upickle.Writer[BigDecimal] {

      case t => Js.Str("" + t)

    }

    implicit val bigDecimal2Reader = upickle.Reader[BigDecimal] {

      case Js.Str(str) => BigDecimal(str)

    }

  }

object BigDecimalFormat extends BigDecimalFormat

//In the base package of your project

//file mycorp/foo/package.scala

package mycorp

package object foo extends BigDecimalFormat {

....

}

//File /mycorp/foo/bars/MyClass.scala

package mycorp.foo

package bars

class MyClass {

  //BigDecimalFormat will be in scope