cancellable

cancellable.rb

module Direct
  # Models that include this mixin must
  #   - have a `cancelled_at` column
  #   - implement paranoia with `deleted_at` column
  # To use this mixin, include the module and call the macro
  # The macro takes options hash that will be forwarded on,
  # to an after_destroy callback. Typically passing a conditional
  #   `if` or `unless` would be appropriate.
  #
  #
  # module Direct
  #   class Flight < ActiveRecord::Base
  #     include Cancellable
  #
  #     cancellable if: :approved_start_date?
  #   end
  # end
  module Cancellation
    extend ActiveSupport::Concern

    included do
      default_scope { where(cancelled_at: nil) }
      validates :deleted_at, absence: true, if: :cancelled_at

      after_destroy :cancel!, after_destroy_args

      scope :with_cancelled, -> { unscope(where: :cancelled_at) }
      scope :only_cancelled, -> { with_cancelled.where.not(cancelled_at: nil) }
    end
  end

  module Cancellable
    extend ActiveSupport::Concern

    module ClassMethods
      def cancellable(args = {})
        cattr_accessor :after_destroy_args
        self.after_destroy_args = args

        include Cancellation
        include InstanceMethods
      end
    end

    module InstanceMethods
      def cancel!
        update_columns(
          cancelled_at: deleted_at,
          deleted_at: nil
        )
      end
    end
  end
end