CODEWITHSUNDEEP
jsonscalaplayframework-2.1
brynjarg
brynjarg

Reputation: 101

Null values in JsObject for Option using play framework 2.1

I've got a case class with some optionals:

case class Person (
  name: String, 
  nationality: Option[String], 
  email: Option[String], 
  gender: Option[String]
)

Using play 2.1.3 I'm trying to create a JSON looking like:

{"name": "Joe", "email": "[email protected]"}

for an object:

val user = new User("Joe, None, Some("[email protected]"), Some("male"))

with:

val myJson = Json.obj("name" -> user.name, 
    "nationality" -> user.nationality, "email" -> user.email)

I however get:

{"name": "Joe", "nationality": null, "email": "[email protected]"}

How can I avoid the nationality with null value in the JSON?

Upvotes: 5

Views: 2480

Answers (2)

boggy
boggy

Reputation: 4027

I know that it is an extremely late response and it doesn't apply in the original context, but it might be useful nowadays. I have this working in Scala 3.3.1 & Play 3.0:

implicit val personWrites: Writes[Person] = new Writes[Person] {

  def writes(o: StudentMarkRow): JsValue =
    val builder = Json.newBuilder
    builder += "name" -> o.name
    if o.nationality.isDefined then builder += "nationality" -> o.nationality.get
    if o.email.isDefined then builder += "email" -> o.email.get
    if o.gender.isDefined then builder += "gender" -> o.gender.get
    builder.result() 
}

One could abstract away the pattern if o.gender.isDefined then builder += "gender" -> o.gender.get maybe as an extension method to Builder trait.

Upvotes: 0

brynjarg
brynjarg

Reputation: 101

After realizing that the problem was related to the play JSON handling, I managed to find a solution inspired by I need advice on Play's Json and elegant Option handling in the Writes trait. I'm not convinced that this is the most elegant solution out there, but it works:

def writes(person: Person): JsValue = {
  JsObject(
    Seq[(String, JsValue)]() ++
    Some(person.name).map("name" -> JsString(_)) ++
    person.email.map("email" -> JsString(_))
  )
}

Upvotes: 5

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