[PlayFramework-2.0] Trouble figuring out custom mappings, pre-filled default data, and ScalaUtils "at-least-one" Every[T] collection type.

FormWithEvery.scala

// This code won't compile without some Play dependencies being satisfied.
// Like Controller, formats.parsing, etc. It's just for reference.
object ArticlesController extends Controller {
  
  import java.util.Locale
  
  // Our application has several translations for an Article:
  val locales: List[Locale] = Seq(Locale.US, Locale.JAPAN)

  def create = Action {
    views.articles.edit(articleCreateForm)
    // So far I haven't figured out if I can provide defaults for the form, based on locales,
    // or if I must fill.
  }
  
  // This is just an "at least one" SeqLike. I like that the constraint
  // "a valid article would have to have a title in at least one locale, doesn't matter which",
  // can be enforced by the type-system.
  import org.scalautils.Every
  
  // Just a list that verifies it's nonEmpty!
  def every[A](mapping: Mapping[A]): Mapping[Every[A]] = {
    RepeatedMapping(mapping)
      .verifying(_.nonEmpty)
      .transform[Every[A]](list => Every(list.head, list.tail:_*), _.toList)
  
  // There has to be a better way I'm not aware of. This feels so wrong, and I have
  // no idea what `format` or `data` actually represent.
  val locale: Mapping[Locale] = Forms.of(new Formatter[Locale] {
    override val format = Some(("format.locale", Nil))
    def bind(key: String, data: Map[String, String]): Either[Seq[FormError], Locale] = parsing(Locale.forLanguageTag, "error.locale", Nil)(key, data)
    def unbind(key: String, value: Locale): Map[String, String] = Map(key -> value.toLanguageTag)
  })
  
  // Finally my form specific case class. Note that you can't construct it without at least
  // one value in titles, ie: One(Locale.US -> "Foo Bar")
  // So it can't be used with form.fill.
  case class ArticleCreateDirective(titles: Every[(Locale, String)], notes: Option[String], active: Boolean)

  // Here's my mapping. It really seems to be that I want the title to be optional
  // as opposed to filtering by _.trim().nonEmpty. But then that means I need a bijective(?)
  // transform from Every[(Locale, Option[String])] to Every[(Locale, String)].
  // Which is fine, that's easy to write. But where do my
  // Locale.JAPAN -> None and Locale.US -> None default values come in then?
  val titleMapping = every(tuple("locale" -> locale, "title" -> optional(text)))
      .verifying(_ exists { case (_, title) => title.isDefined })

  val articleCreateForm = Form(
    mapping(
      "titles" -> titleMapping,
      "notes" -> optional(text),
      "active" -> boolean,
    )(ArticleCreateDirective.apply)(ArticleCreateDirective.unapply))

  // Right now I don't have a solution I'm happy with. So what I'm doing is changing
  // ArticleCreateDirective.titles to an Every[(Locale, Option[String])], and 
  // definining a companion-object def empty that populates the configured locales with
  // None entries.
  // 
  // I'll have to do the same for my UpdateDirective (not shown here). And then during
  // persistence run my filter.
  //
  // The problem of all that is that I'm losing the entire point of using an Every
  // if I can have an Every[Option[T]] that's actually empty when flattened. I'm only
  // guaranteeing that I'll get a runtime error if I don't guard with verifying checks
  // in the mappings (as above) instead of persisting bad data to the database. Which
  // is better than nothing. But it's very dissapointing I can't figure out how to do
  // this cleaner with some sort of RepeatedMappingWithADefaultSet, so that I could have
  // optional(text) on the form side, still have my every mapping, my case classes can
  // be clean of the Every[Option] hacks, and I can still pre-fill my default entries
  // for the locales to be used with a helper.repeat call in my template.
}