baclight/app/models/id_card/field_exception_item.rb

module IdCard
    class FieldExceptionItem < ApplicationRecord
        belongs_to :field_exception
        belongs_to :network_logo, optional: true
        belongs_to :provider_section, optional: true

        validate :only_one_exception_field_present

        FIELDS_TO_VALIDATE = [:field_value, :card_logo_file_id, :card_provider_id].freeze

        VALID_FIELD_NAMES = ['network_logo', 'provider_section', 'effective_date']

        validates :field_name, inclusion: { in: VALID_FIELD_NAMES,
                                        message: "%{value} is not a valid Id Card Field Name" }


        private

        def only_one_exception_field_present
            present_fields = FIELDS_TO_VALIDATE.count { |field| self[field].present? }

            if present_fields != 1
                errors.add(:base, "Only one exception field can be present at a time")
            end
        end
    end
end