demarches-normaliennes/app/models/champs/iban_champ.rb

class Champs::IbanChamp < Champ
  validates_with IbanValidator, if: -> { validation_context != :brouillon }
  after_validation :format_iban

  def for_api
    to_s.gsub(/\s+/, '')
  end

  def for_api_v2
    for_api
  end

  private

  def format_iban
    self.value = value&.gsub(/\s+/, '')&.gsub(/(.{4})/, '\0 ')
  end
end