Scala / Play2 - dynamic constraints based on checkbox value

Question

I hava a template that creates a checkbox and a text input field:

@helper.checkbox(inputForm("live"), 'checked -> true, 'onclick -> "hideTextFields()")
@helper.inputText(inputForm("target"), 'disabled -> true)

When unchecking the checkbox, the text fields get visible (and vice versa). This is done in a javascript function called hideTextFields().

Now, in the controller I need to have a constraint, that makes the text input field mandatory as soon as the checkbox is unchecked.

I have a mapping:

"live" -> boolean
"target" -> nonEmptyText

but this always requires the target to be specified.

How can I achieve dynamic constraints for the text input field based on the checkbox's state. Play is version 2.3.4.

Thank you and best regards!

Answer 1

Check out the verifying methods that are on Mapping, which you get back from tuple() and mapping()

Simple example:

val sample = Form(
  tuple(
    "checkbox" -> boolean,
    "text" -> text
  ).verifying(
    "If checkbox checked text cannot be empty", 
    (tuple) => !tuple._1 || tuple._2.nonEmpty)
  )

You can find another example under "Defining ad-hoc constraints" in the play framework docs: The playframework docs