Manually validate a text

Question

I want to validate a text (JSON) received from an ajax request.

val myValidation: Mapping[String] = ///...

def setNewNameAjax = Action { request =>
  val json = Json parse request.body.asJson.get.toString
  val name = (json \ "name").toString()
  // how do I manually validate "name" by myValidation?
}

So the aim is to validate name using my validator myValidation. And, preferably, sensibly return the result in case of a validation error. How do I do this?

The goal is not to validate JSON in particular. The goal is to validate any kind of a text using a custom vaditor (in this case, it's myValidation).

Answer 1

That's actually a bad idea to validate against a Mapping. A Mapping should be used to handle a form field and it expects a Map[String, String] instead of just a value to be validated.

However, you can validate a value using a Mapping[T]. It's just a little trickier. In general I'd advise to validate a String value using Constraint[String] but here's the working code:

val myValidation: Mapping[String] = ///...

def setNewNameAjax = Action { request =>
  val json = Json parse request.body.asJson.get.toString
  val name = (json \ "name").toString()
  //one mapping may have multiple constraints, so run the validation for all of them and collect the list of ValidationResults
  val validationResults = myValidation.constraints.map(_(name))
  //filter the list - leave only the conditions that failed
  val failedValidationResults = validationResults.filter(_.isInstanceOf[Invalid])
  failedValidationResults match {
    case Nil => //Validation OK, no constraints failed
    case _ => //Validation failed, assemble the message and inform the user
  }
}