JSON/Playframework invalid type

Question

I'm having some troubles parsing a JSON response with Play 2.1 parser. Say I receive the following json as a string:

{"name": "myName"}

I'm able to parse it using these few lines...

case class MyJsonObj(name: String)
implicit val jsonRead = (
  (__ \ "name").read[String])(MyJsonObj.apply _)
val myObj = Json.parse("{\"name\": \"myName\"}").valide[MyJsonObj]

Now say I receive almost the same message but instead of having a string as "myName" I receive a null (i.e: {"name": null}), the parsing fails... Ideally, whenever I receive a null, I would like to put a default value (instead of raising an error) and keep parsing.

Any suggestions? Thanks!

Answer 1

You can achieve this with readNullable or orElse:

(__ \ 'name).readNullable[String].map(_.getOrElse("default"))
// Another solution:
(__ \ 'name).read[String] orElse Reads.pure("default")

Note: Readers don't work fine with "one-field" case class (but I suppose it's just for this example). Otherwise, see this topic.