GCPAccess.scala

import com.google.cloud.datastore.Entity.Builder
import com.google.cloud.datastore._

import scala.util.Random

object GCPAccess {

  val datastore: Datastore = DatastoreOptions.getDefaultInstance.getService
  val rnd                  = Random

  def add(kind: Kind, key: Long): Entity = {
    val newKey    = datastore.newKeyFactory.setKind(kind.name).newKey(key)
    put(kind, newKey)
  }

  def add(kind: Kind, name: String): Entity = {
    val newKey = datastore.newKeyFactory.setKind(kind.name).newKey(name)
    put(kind, newKey)
  }

  private def put(kind: Kind, newKey: Key): Entity = {
    val newEntity = Entity.newBuilder(newKey)
    datastore.put(kind match {
      case foo: Foo => putFoo(newEntity, foo)
    })
  }

  private def putFoo(entityBuilder: Builder, foo: Foo): Entity = {
    entityBuilder
      .set("bar", foo.bar)
      .build()
  }
}

GCPKinds.scala

sealed trait Kind {
  val name = this.getClass.getSimpleName
}

case class Foo(bar:String) extends Kind