Select a random document using

ReactiveMongoRandomDocument

import reactivemongo.bson.BSONDocument
import reactivemongo.api.collections.default.BSONCollection
import reactivemongo.api.{QueryOpts, DB}
import reactivemongo.core.commands.Count
import reactivemongo.api.collections.default._

def getDocument(collection: BSONCollection): Future[Option[YourClass]] = {
    val futureCount = db.command(Count(collection.name))
    futureCount.flatMap { count =>
      val skip = Random.nextInt(count)
      collection.find(BSONDocument()).options(QueryOpts(skipN = skip)).one[YourClass]
    }
  }