如何从Argonaut Json对象中删除具有空值的键

Question

How can an extension method be written to remove all keys with a null value from an Argonaut Json object:

I tried this:

package object Extensions {
  implicit class JsonExtensions(val json: Json) extends AnyVal {
    def removeNulls: Json = {
      json.withObject(j => JsonObject.from (j.toMap.filter(!_._2.isNull).toList))
    }
  }
}

but it only seems to be removing keys with null values at the top level of the Json object...

Answer 1

Argonaut supports this internally, you can use PrettyParams to do what you're after:

def removeNulls: Json = {
  json.pretty(PrettyParams.nospace.copy(dropNullKeys = true)).toJson
}

Hope this covers your question!