validator_with_validations.rb

class EsimValidator < ActiveModel::Validator
  include ActiveModel::Validations

  validates_presence_of :name, :voucher_type, :delivery_date, :expiration_date
  validates_numericality_of :sales_partner_id, :greater_than => 1, :only_integer => true

  attr_accessor :record

  def errors
    record.errors
  end

  def validate(record)
    self.record = record
    valid?
  end

  def method_missing(method, *args, &block)
    super unless record && record.respond_to?(method)
    record.send method, *args, &block
  end

end