Input validation

[takezoe]

I have some ideas to introduce validation capability to Resty.

assert properties in the constructor

The simplest idea is assert in the constructor of the case class:

case class Message(message: String){
  assert(message.nonEmpty, "message is empty.")
}

Response would be:

{
  "errors": [
    "assertion failed: message is empty."
  ]
}

validate method of the case class

Second idea is implementing validation logic as validation() method of the case class:

case class Message(message: String) extends ValidationSupport {
 override def validate(): Option[ErrorModel] = {
   if(message.isEmpty){
     Some(ErrorModel(Seq(message is empty.)))
   } else {
     None
   }
 }
}

annotation for the case class

Third idea is providing validation annotations for the case class:

case class Message(
  @NonEmpty @MaxLength(100) message: String
)

BeanValidation might be another choise instead of original annotations.