How to have a common rule for 2 validators?

[mii9000]

Maybe inherit from a base rule?
What I want is not to repeat the same rules in multiple validators.

[krzemin]

Hey, sure, it's possible with octopus.
I'm guessing you have some base trait and few case classes extending it.

sealed trait Person {
  def id: Int
  def name: String
}

case class Employee(id: Int, name: String, salary: Long) extends Person

case class Employer(id: Int, name: String, employees: List[Employee]) extends Person

Let's define validators for base trait and compose them with rules for case classes.

import octopus.dsl._

implicit val personValidator: Validator[Person] = Validator[Person]
  .rule(_.id > 0, "id must be greater than 0")
  .rule(_.name.trim.nonEmpty, "name must not be empty")

implicit val employeeValidator: Validator[Employee] = Validator[Employee]
  .composeSuper(personValidator)
  .rule(_.salary >= 10000, "salary must be at least 10000!")

implicit val employerValidator: Validator[Employer] = Validator[Employer]
  .composeSuper(personValidator) // employer is also a person, so it validate its id and name
  .composeDerived // composing derived validator for list of employees

See how they work.

import octopus.syntax._

val badEmployee = Employee(0, "", 500)

badEmployee.validate
// invalid:
//  : id must be greater than 0
//  : name must not be empty
//  : salary must be at least 10000!

val goodEmployee = Employee(3, "John", 15000)

goodEmployee.validate
// valid

val badEmployer = Employer(-5, "", List(badEmployee))

badEmployer.validate
// invalid:
//  : id must be greater than 0
//  : name must not be empty
//  employees[0]: id must be greater than 0
//  employees[0]: name must not be empty
//  employees[0]: salary must be at least 10000!

val goodEmployer = Employer(5, "Mike", List(goodEmployee))

goodEmployer.validate
// valid

Hope it helps.