ruby.rb

class Device < ActiveRecord::Base
  belongs_to :participant

  validates :participant, presence: true
  validates :provider, presence: true
  validates :serial_number, presence: true, uniqueness: { scope: :provider }
  validates :serial_number, format: { with: /\A\d{15}\z/, message: 'IMEI must be 15 digits'},
    if: lambda { |d| d.provider == 'bodytrace' }

  before_validation :normalize

  private

    def normalize
      self.provider      = provider&.downcase
      self.serial_number = self.class.normalize_serial_number serial_number
    end
end