application process

eg.rb

# The code smell: disjoint radio buttons reveal that some values that
# should have hung together didn't, and that there were also dependent
# fields (the data protection checkbox and the application form link)
# which were hanging around and being a little bit problematic
#
# A solution is to use one field that can hold several values, unlike the
# boolean which can only hold two.
#
# We can also introduce a VALUE OBJECT that represents this field and can
# also tell us which (if any) of the dependent fields are needed.
#
# We can also extract the complex bits of the validations to a module so
# that they're more contained and we isolate the interactions with the
# Value objects.
module ApplicationProcess
  module Validator
    def self.data_protection_confirmation
      {
        if: ->(event) { Value.new(event).requires_data_protection? },
        allow_nil: false
      }
    end

    def self.application_link
      {
        if: ->(event) { Value.new(event).requires_application_link? },
        presence: true,
        format: { with: /(http|https):\/\/.+\..+/ }
      }
    end

    def self.value
      {
        inclusion: {
          in: Value::VALUES
        },
        presence: true
      }
    end
  end

  class Value
    VALUES = %w{selection_by_travis selection_by_organizer application_by_organizer}

    attr_reader :event

    def initialize(event)
      @event = event
    end

    def value
      event.application_process
    end

    def requires_data_protection?
      value == 'selection_by_organizer'
    end

    def requires_application_link?
      value == 'application_by_organizer'
    end

    def valid?
      VALUES.include?(value)
    end
  end
end

event.rb

class Event < ActiveRecord::Base
  # application_process :string
  validates :application_process, ApplicationProcess::Validator.value
  validates_acceptance_of :data_protection_confirmation, ApplicationProcess::Validator.data_protection_confirmation
  validates :application_link, ApplicationProcess::Validator.application_link
end

# For viele points:
class Event < ActiveRecord::Base
  include ApplicationProcess::Validator
end