multi-predicates.rb

require 'bundler/inline'

gemfile(true) do
  source 'https://rubygems.org'

  gem 'dry-validation'
end

module Predicates
  include Dry::Logic::Predicates

  predicate(:shift?) do |value|
    %w(Up Down UpRate DownRate).include? value
  end

  predicate(:up?) do |value|
    %w(Up UpRate).include? value
  end

  predicate(:down?) do |value|
    %w(Down DownRate).include? value
  end

  predicate(:rate?) do |value|
    %w(UpRate DownRate).include? value
  end
end

schema = Dry::Validation.Schema do
  configure do
    predicates(Predicates)

    def self.messages
      super.merge(
        en: { errors: {
          shift?: '%{value} not shift',
          up?: '%{value} not up',
          down?: '%{value} not down',
          rate?: '%{value} not rate',
        } }
      )
    end
  end

  optional(:y).filled(:shift?)

  optional(:x).filled(:int?)
    .when(included_in?: [1, 3]) {
      required(:y).filled(:up?)
    }
    .when(included_in?: [2, 4]) {
      required(:y).filled(:down?)
    }
    .when(included_in?: [3, 4]) {
      required(:y).filled(:rate?)
    }
end

(1..4).each do |i|
  p schema.({x: i, y: "A"})
  p schema.({x: i, y: "Up"})
  p schema.({x: i, y: "Down"})
  p schema.({x: i, y: "UpRate"})
  p schema.({x: i, y: "DownRate"})
end