Default values ​​for Virtus in rails

I am using virtus (1.0.5) with rails (5.0.2). I am using Virtus for the model as it has validations based on the page available.

My organization model is

class Organization < ApplicationRecord
  validates :name, presence: true
end

      

        
        
        
      

    

and the form created using virtus is

class OrganizationProfileForm
  include ActiveModel::Model
  include Virtus.model

  attribute :call_center_number, String, default: :org_call_center_number

  validates :call_center_number, presence: true

  def initialize(organization)
    @organization = organization
  end

  private

  def org_call_center_number
    @organization.call_center_number
  end

end

      

        
        
        
      

    

Unfortunately the above code doesn't work

Loading development environment (Rails 5.0.2)
2.3.0 :001 > of = OrganizationProfileForm.new(Organization.last)
Organization Load (0.6ms)  SELECT  "organizations".* FROM "organizations" ORDER BY "organizations"."id" DESC LIMIT $1  [["LIMIT", 1]]
=> #<OrganizationProfileForm:0x007f9d61edd6a8 @organization=# <Organization id: 1, name: "Some name", call_center_number: "4892374928", created_at: "2017-03-29 09:35:22", updated_at: "2017-03-29 09:37:59">>
2.3.0 :002 > of.call_center_number
=> nil