Play 2: idiomatic approach to binding a form to List[Model] - forms

Question

I have several CRUD operations to perform, each one on a collection of models (e.g. game schedule, team roster, game result, game stats, etc.).
Up to this point in my Play experience (just a few months, 1 project live) I have been working with one-to-one form binding to model instance.
I know I can numerically index form field names, but then how to bind the posted form to List[Model]?
This is what my one-to-one binding looks like:
// abstract away bindFromRequest to make binding more concise in controllers
def bindForm[T](f: play.api.data.Form[T])(implicit r: play.api.mvc.Request[_]) =
f.bindFromRequest fold(e=> Left(e.errorsAsJson), Right(_))
and then in controllers:
val result = for {
model <- bindForm(form).right
id <- dao.create(model) as json
} yield id
what I would like to do is the same, but instead of model binding returning a single Model on success, have it return a List[Model], and pass on to overloaded DAO create/edit/delete operations.
I see that there is a list method that one can use as part of a Form mapping, but I have a feeling that that would wreak havoc with my JDBC query wrapper (ScalaQuery/Slick), whose case class/companion object mapping would likely not play well with collections properties.
For example, existing mapping of a game schedule looks like:
object CompositeForm {
import play.api.data.{Form, Forms}, Forms._
import utils.Validator.Bindings.jodaLocalTimeFormat
val mapper = mapping(
'id -> ignored(0),
'gameDate -> jodaDate,
'gameType -> optional(text),
'location -> optional(text),
'team1 -> number,
'team2 -> number
)(Composite.apply)(Composite.unapply)
val form = Form( mapper )
}
using list(gameDate), list(gameType) instead then means that form binding will return a single Composite instance whose properties are all collections -- maybe it will work, but doesn't seem nearly as clean/straightforward as working with a collection of model instances.
Ideas appreciated ;-)

Answer 1

The as yet documented seq() option in play form mapping was pointed out to me on Play google group by #Julien Richard-Foy
Using repeat() and seq() together allows one to repeat a form mapping, thus creating a collection of indexed foo.bar[n] formfield elements.
Example
object ScheduleForm {
import play.api.data.{Form, Forms}, Forms._
val mapper = mapping(
'composite -> seq(CompositeForm.mapper),
'note -> seq(ScheduleNoteForm.mapper)
)(Schedule.apply)(Schedule.unapply)
val form = Form( mapper )
}
and then in a view:
#repeat(_form("composite"), min=#numGames) { f=>
#inputDate(f("gameDate"), '_label-> "Game Date", 'class-> "required")
...
}