Akka HTTP Json Marshalling - json

Question

I'm building simple REST API using Akka-HTTP and MongoDB for persistence. For Marshalling and Unmarshalling HTTP requests I'm using spray json. Following MongoDB documentation I defined entities like that:
package entities
import org.mongodb.scala.bson.ObjectId
case class Person(
_id: ObjectId,
firstName: String,
lastName: String,
email: String,
emailConfirmed: Boolean,
telephone: String,
...
)
object Person {
def apply(
firstName: String,
lastName: String,
email: String,
telephone: String,
...
): Publisher = new Publisher(
new ObjectId(),
firstName,
lastName,
email,
false,
telephone,
...
)
}
The problem with this approach is that I have to write a lot of boilerplate code to enable Marshalling-Unmarshalling:
implicit object PublisherItemFormat extends RootJsonFormat[Publisher] {
def write(publisher: Publisher) = JsObject(
"_id" -> JsString(publisher._id.toString),
"firstName" -> JsString(publisher.firstName),
"lastName" -> JsString(publisher.lastName),
"email" -> JsString(publisher.email),
"telephone" -> JsString(publisher.telephone),
...
)
def read(json: JsValue) = {
val jsObject = json.asJsObject
jsObject.getFields(
"_id",
"firstName",
"lastName",
"email",
"telephone",
...
) match {
case Seq(
_id,
firstName,
lastName,
email,
telephone,
...
) ⇒ Publisher(
firstName.convertTo[String],
lastName.convertTo[String],
email.convertTo[String],
telephone.convertTo[String],
...
)
}
}
}
I have approx 10 different entities that have to be saved in the Mongo, and each of them have 5-15 fields. With this number of entities, this kind of approach will produce too much boilerplate.
What could be a better way of doing it, with less boilerplate ? May-be there is another Json-serialization library instead of "spray-json" which can figure things out automatically with less code ?
Or how can I define Marshalling class for org.mongodb.scala.bson.ObjectId using Spray-Json ? This will also help to get rid of boilerplate code.

Answer 1

Use automatic derivation:
object EntitesJsonProtocol extends SprayJsonSupport with DefaultJsonProtocol {
implicit val placeResponseFormat = jsonFormat19(Person.apply)
def personToJson(p: Person) = p.toJson
}
the personToJson method is implemented so you don't have to contaminate your code with json imports, note that the order of declaration is important if a person is embedded inside a publisher you will have to declare personFormat before publisherFormat