Circe: Exclude Options with None

[darkfrog26]

I'm generating JSON for working with ArangoDB and it distinguishes between null and not set. This creates a problem since the default operation of Circe semi-auto encoding of Option set to None is null. Is there some way to configure this? I would also argue that exclusion should be the default operation anyway since it would result in more compact JSON.

[jonas]

This looks like a duplicate of #584. Here's an example of how to omit None fields:

scala> :paste
// Entering paste mode (ctrl-D to finish)

import io.circe.generic.auto._
import io.circe.Printer
import io.circe.syntax._

case class C(a: Option[String], b: Option[Int], c: Boolean)

val printer = Printer.noSpaces.copy(dropNullKeys = true)


// Exiting paste mode, now interpreting.

import io.circe.generic.auto._
import io.circe.Printer
import io.circe.syntax._
defined class C
printer: io.circe.Printer = Printer(true,true,,,,,,,,,,,,,,,,)

scala> printer.pretty(C(Some("a"), None, false).asJson)
res0: String = {"a":"a","c":false}

scala> printer.pretty(C(None, None, false).asJson)
res1: String = {"c":false}

[ksilin]

dropNullKeys has been changed to the more fitting dropNullValues:

val printer = Printer.noSpaces.copy(dropNullValues = true)

[hairylime]

Not sure if this is what the OP meant, but it sounds like they are asking for a selective solution - I have something similar with a Tri valued object (think Option, with 2 'None' values, None meaning 'unset'/'set to null', and 'Do not care' meaning ignore that field) - I can just map the 'Some'-ish and the None-ish case to Option, but can't see a way to drop the Json for the Do not care case...

[travisbrown]

Now that we have dropNullValues on both the printer and Json I think we can close this.