Play 2: How to parse a dynamic list of form inputs in Scala controller?

Question

I have a form where the number of input fields is dynamic.

How can these input fields be mapped with a play form? Let's say, the name of each input tag is 'foo_x' where x is an integer that is incremented each time a new input field is dynamically created on the client side. Is there any automatic mapping in Play available or do I have to do this 'by hand' and if so, how can this be done?

Answer 1

As Brian mentioned, the Play documentation has an example of repeated values that should suit your needs.

Also, bear in mind that you can nest mapping definitions. As an example, I have something like the following:

val editUserForm: Form[User] = Form(
    mapping(
        "username" -> text(minLength = 4, maxLength = 50),
        "emails" -> list(optional(email)).verifying(Messages("error.mandatoryEmail"), e => e.size > 0),
        "urls" -> list(text(maxLength = 255)),
        {
            // Binding: Create a User from the mapping result
            (username, emails, urls) => {
              // Here, emails is a List[Option[String]] 
              // and urls is a List[String]
            }
        } {
            // Unbinding: Create the mapping values from an existing User value
            user => Some(user.username, 
                        user.emails.map(e => Some(e.email)), 
                        user.urls.map(_.url))
        }
    )

There's quite a bit happening there, but the important bit that I wanted to show is that I'm nesting list with optional with email, and verifying that the list has at least one non-empty element - effectively forcing the user to enter at least one element in the list.

Hope this helps.

Answer 2

See "Repeated values" in the Play2 Documentation.

You can have these mapped into a List automatically provided you follow the naming convention.