Extract Options from potentially null JSON values using for expression

Question

I have a JSON document where some values can be null. Using for expressions in json4s, how I can yield None, instead of nothing?

The following will fail to yield whe

Answer 1

According to the documentation,

Any value can be optional. Field and value is completely removed when it doesn't have a value.

scala> val json = ("name" -> "joe") ~ ("age" -> (None: Option[Int]))

scala> compact(render(json))

res4: String = {"name":"joe"}

Explaining why your for comprehension doesn't yield anything.
Of course, a null value is mapped to None internally.