Created dynamic parameter validator

[jeroenr]

Allows easy validation of multiple parameters against multiple constraints. To check, for instance, if a few numeric parameters are within range [0, 100]:

def myAction(param1: Option[Int], param2: Option[Int]) = Action {
   implicit request =>
     ParameterValidator(Seq(Contraints.min(0), Constraints.max(100)), param1, param2) match {
        case Valid => Ok
        case Invalid(errors) => BadRequest(errors.mkstring(", "))
    }

Unit tests are included

[huntc]

Can you please flatten the two commits. Thanks

[jroper]

Need to think about this, here we're talking about introducing validation on raw values, not on some structure (eg a form). It may be better to introduce this into the parameter binding API rather than here.

[jeroenr]

@huntc done :) @jroper as far as I could tell none of the constructs in the play/api/data/validation/Validation.scala file assumes we are in a form context. The form related validation is in the play/api/data/Form.scala file, so Validation.scala seemed to be the right place

[jroper]

@jeroenr You're right, but I think actually what's happening here is we're introducing a new structure, a list of options, and validating that. Just like the form validation code is outside of this, and the JSON validation code is outside of this, perhaps this also should be somewhere else. Or perhaps not. I'd just like to consider the alternatives.

[jeroenr]

@jroper Ok that makes sense. I've been playing around combining the validation logic with custom QueryStringBindable's. It fits well, so I can definitely see your point now about moving the validator to the parameter binding API.

[jroper]

Let's just call this a handy little validation and put it here for now.

[jeroenr]

Awesome 👍