play List JSON serialization

gistfile1.txt

No Json deserializer found for type List[models.Subscription]. Try to implement an implicit Writes or Format for this type.
In /Volumes/HD/Users/nicolas/Boulot/cloudbees/je-sp/app/controllers/API.scala at line 25.

val subscriptions: List[Subscription] =  ???

22          Ok(
23            Json.obj("account" -> account.getName,
24                     "salesforce_id" -> account.getId,
25                     "subscriptions" -> subscriptions, 
26                     "licenses" -> "TODO",
27                     "credits" -> "TODO")

class Subscription(...) extends Writes[Subscription]{
  def writes(o: Subscription): JsValue = {
    Json.obj(
      "product" -> product,
      "expiration" -> FastDateFormat.getInstance("dd-MM-yyyy").format(expiration))
  }
}

What is class Subscription(...) extends Writes[Subscription] ?

You need to provide an implicit val/object implementing Writes[Subscription].

You can put it in the companion object Subscription to have it implicitly with any instance of Subscription.

You can also try if you don't want to implement your own Writer

implicit val subscriptionFormat = Json.format[Subscription]